//////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20364 SUBJECT: LIGO/Virgo G268556: Identification of a GW CBC Candidate DATE: 17/01/04 16:49:56 GMT FROM: Peter Shawhan at U of Maryland/LSC The LIGO Scientific Collaboration and Virgo report: The online pycbc CBC analysis identified a candidate with GraceDB ID G268556 during processing of data from LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at 2017-01-04 10:11:58.599 UTC (GPS time: 1167559936.599). G268556 is an event of interest because its false alarm rate, as determined by preliminary analysis, is less than (i.e., more significant than) 6.1e-08 Hz (about one in 6 months). The event's properties can be found at this URL: https://gracedb.ligo.org/events/G268556 Based on preliminary matched-filter estimates of the masses and spins, there is a 0% chance that the less massive companion in the binary has a mass less than 3 Msun. Based on the tidal disruption condition and disk mass formula of Foucart (PRD 86, 124007), using an implementation based on Pannarale & Ohme (ApJL 791, 7), we estimate that there is a 0% chance that the system ejected enough neutron-rich material to power an electromagnetic transient. One sky map with distance information (e.g., Singer et al. 2016, ApJL 829, 15) is available at this time and can be retrieved from the GraceDB event page: bayestar.fits.gz, an initial localization generated by the BAYESTAR pipeline. The probability is concentrated in two long, thin arcs. The 50% credible region spans about 400 deg2 and the 90% region about 1600 deg2. This is the preferred sky map at this time. This event was also detected by the cWB unmodeled burst search, with a sky map consistent with the one from BAYESTAR. The event candidate was not reported by the low-latency analysis pipelines because re-tuning the calibration of the LIGO Hanford detector is not yet complete after the holiday shutdown. This resulted in a delay of over 4 hours before the candidate could be fully examined. We are confident that this is a highly significant event candidate, but the calibration issue may be affecting the initial sky maps. We will provide an update in approximately 48 hours which may include an improved sky map. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20365 SUBJECT: LIGO/Virgo G268556: Fermi GBM Observations DATE: 17/01/04 21:18:26 GMT FROM: E. Burns at U of Alabama/Huntsville E. Burns (UAH) reports on behalf of the GBM-LIGO Group: Lindy Blackburn (CfA), Michael S. Briggs (UAH), Jacob Broida (Carleton College), Jordan Camp (NASA/GSFC), Tito Dal Canton (NASA/GSFC), Nelson Christensen (Carleton College), Valerie Connaughton (USRA), Adam Goldstein (NASA/MSFC), Rachel Hamburg (UAH), C. Michelle Hui (NASA/MSFC), Pete Jenke (UAH), Dan Kocevski (NASA/MSFC), Nicolas Leroy (LAL), Tyson Littenberg (NASA/MSFC), Julie McEnery (NASA/GSFC), Rob Preece (UAH), Judith Racusin (NASA/GSFC), Peter Shawhan (UMD), Karelle Siellez (GA Tech), Leo Singer (NASA/GSFC), John Veitch (Birmingham), Peter Veres (UAH), Colleen Wilson-Hodge (NASA/MSFC) GBM was observing 82.4% of the initial LIGO BAYESTAR probability map for G268556 at event time, with a large part of the southern high probability region occulted by the Earth (specifically, locations within ~67 degrees of (RA=297.7, Dec=-25.3)). The closest on-board trigger time was more than 12 hours earlier and was due to high particle activity on entry to the SAA. The untargeted ground-based SGRB search of GBM data between ten and eleven UTC (Briggs et al., in prep) found no candidates around G268556. The targeted search of the GBM data ([1], [2]) also did not find a significant gamma-ray signal. This search processes time scales of 0.265 to 8.192 s within 30 s of the LIGO event. The most significant candidate was found on the longest timescale with the soft spectral template, corresponding to a false alarm rate of ~0.003 Hz. The 8.192 s window of this candidate begins 5.4 s before the T0 of G268556. The location identified by the search is consistent with the high probability region of the LIGO annulus, with the GBM localization peaking around (130, 10); the targeted search location is marginally consistent with a galactic origin. However, the signal appears in detectors observing different regions of the sky. Further investigation rules out a solar origin. There is longer term structure for tens of seconds in the low energy channels of GBM. Both prompt and longer term upper limits will be sent in a forthcoming circular. [1] L. Blackburn et al. 2015, ApjS 217, 8 [2] A. Goldstein et al. arXiv:1612.02395 //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20366 SUBJECT: LIGO/Virgo G268556: INTEGRAL search of temporally coincident prompt hard X-ray emission DATE: 17/01/04 22:55:59 GMT FROM: Carlo Ferrigno at ISDC/INTEGRAL V. Savchenko and C. Ferrigno (ISDC, University of Geneva, CH) on behalf of the INTEGRAL group: S. Mereghetti (IASF-Mi, Italy), E. Kuulkers (ESTEC/ESA, The Netherlands), A. Bazzano (IAPS-Roma, Italy), E. Bozzo, T. J.-L. Courvoisier (ISDC, University of Geneva, CH) S. Brandt (DTU - Denmark) R. Diehl (MPE-Garching, Germany) L. Hanlon (UCD, Ireland) P. Laurent (APC-CeA, France) A. Lutovinov (IKI, Russia) J.P. Roques (CESR, France) R. Sunyaev (IKI, Russia) P. Ubertini (IAPS-Roma, Italy) We investigated serendipitous INTEGRAL observations carried out at the time of the LIGO/Virgo G268556. The satellite was pointing at RA = 00:04:02 Dec=+67:14:38, away from the high-probability region, derived from the LIGO Bayestar pipeline. The anti-coincidence shield of spectrometer on board of INTEGRAL (SPI/ACS) covered the full LIGO 90% confidence region and provided the most stringent constraints on the flux of a possible electromagnetic counterparts in the energy range covered by INTEGRAL instruments. We investigated the SPI-ACS light curve between -100 and +100 s from the trigger time (2017-01-04 10:11:59 UTC) on temporal scales from 0.1 to 10 s and found no significant excesses over a very stable background. The SPI/ACS light curves, binned at 50 ms, are derived from 91 independent detectors with different lower energy thresholds (mainly between 50 keV and 150 keV) and an upper threshold at about 100 MeV. The ACS response varies as a function of the incident angle. Assuming an optimal perpendicular direction of the burst to the INTEGRAL pointing direction, we estimate a 3-sigma upper limit corresponding to fluences of 1.6e-7 erg/cm2 for a 1 s duration, 4.5e-7 erg/cm2 for 10 s, and 5e-8 erg/cm2 for 0.1 s. For this computation, we adopt a low threshold at 100 keV and Band model parameters −0.5, −2.5 with peak E_0 ~ 600 keV. The optimal orientation is compatible with a large part of the high-probability sky region of the trigger. The limit anywhere in the 90% confidence range of the LIGO Bayestar localisation is at most 50% less stringent. Investigations of the light curves from the other INTEGRAL instruments covering part of the LIGO localisation region (IBIS VETO, ISGRI, and PICsIT) did not reveal any significant transient event in the 200 s temporal window centred on LIGO/Virgo G268556, but provide less stringent upper limit on the fluence. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20369 SUBJECT: LIGO/Virgo G268556: observation regions by Project Mini-GWAC of SVOM DATE: 17/01/05 15:52:45 GMT FROM: Chao Wu at NAOC J.Y. Wei (NAOC), X.H. Han (NAOC), N.Leroy (LAL), C. WU (NAOC), S. Antier (LAL), L.P. Xin (NAOC), X.M. Meng (NAOC), L. Huang (NAOC), Y. Xu (NAOC), H.B. Cai (NAOC), J. Wang (NAOC), X.M. Lu (NAOC), Y.L. Qiu (NAOC), J.S. Deng (NAOC), L. Cao (NAOC), S. Wang (NAOC), E.W.Liang (GXU), Y.G. Yang (HBNU), B. Cordier (CEA), S.N. Zhang (NAOC), S. Basa (LAM), B.B. Wu (IHEP), Jean-Luc Atteia (IRAP), D. Götz (CEA), C. Lachaud (APC) on behalf of the SVOM Gravitational Astronomy group report: We observed about 5600 square degree (14 sky regions) of the skymap of the advanced LIGO trigger G268556, with Mini-GWAC (Mini Ground Wide Angle Camera), at Xinglong Observatory of NAOC equipped with U9000 camera (FOV~400 square degree/camera). Mini-GWAC, as a part of ground instruments of SVOM mission, comprises 12 wide field angle cameras (aperture=7cm), working with unfiltered band. The observations are operated in time-series mode, taking one exposure in 15 seconds (10s exposure + 5s readout). The limit magnitude is ~12 mag in R band. We estimate a 84.4% prior probability that these 14 regions contain the true location of the source. The coordinates of the 14 regions and observation time are list following: Ra Dec Camera_ID start-obs(UTC) end-obs(UTC) Camera_ID start-obs(UTC) end-obs(UTC) 07:46:49.578 +29:35:33.46 C1 12:30:41.1 13:49:41.5 C3 19:14:39.9 21:17:22:8 07:48:54.239 +10:34:56.09 C2 12:30:41.1 13:49:49.5 C4 19:14:39.9 21:17:36.8 09:10:51.599 +29:36:54.60 C1 13:50:29.3 15:14:52.1 09:12:54.096 +10:36:25.88 C2 13:50:29.3 15:14:44.2 10:34:57.404 +29:33:02.67 C1 15:15:28.4 16:22:20.7 10:36:57.072 +10:32:32.51 C2 15:15:28.4 16:22:07.9 09:17:21.644 +69:37:03.40 C1 19:14:27.3 22:39:37.7 09:21:25.794 +50:35:59.26 C2 19:14:27.3 22:39:25.3 11:52:01.006 +70:06:03.83 C3 16:21:28.7 17:57:31.9 C5 19:14:32.9 22:39:31.9 12:02:07.741 +50:03:10.98 C4 16:22:17.5 17:57:30.2 C6 19:14:32.9 22:39:25.2 06:34:42.357 +69:28:01.79 C5 14:55:58.2 17:57:22.7 06:40:16.529 +50:28:28.89 C6 14:56:10.4 17:57:35.7 14:34:10.239 +70:01:52.84 C7 19:14:55.3 22:39:18.3 14:44:41.102 +49:56:05.18 C8 19:14:55.3 22:39:21.9 Mini-GWAC is working in sky survey mode. The first image was taken 2 hours 20 minutes after event. No any significant transient is found in our online pipeline. The image analysis is ongoing in detailed processing with our offline pipeline. Further observations of these fields are planned. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20370 SUBJECT: LIGO/Virgo G268556: ANTARES search DATE: 17/01/05 16:07:50 GMT FROM: Damien Dornic at CPPM/CNRS M. Ageron (CPPM/CNRS), B. Baret (APC/CNRS), A. Coleiro (APC/Universite Paris Diderot), D. Dornic (CPPM/CNRS), A. Kouchner (APC/Universite Paris Diderot), T. Pradier (IPHC/Universite de Strasbourg) report on behalf of the ANTARES Collaboration: Using on-line data from the ANTARES detector, we have performed a follow-up analysis of the recently reported LIGO/Virgo G268556 event using the initial LIGO BAYESTAR probability map at event time. The ANTARES visibility at the time of the alert together with the 90% contour of the probability map are shown in: https://www.cppm.in2p3.fr/~dornic/events/G268556.png (gwantares/ANT@GW). Considering the location probability provided by the LIGO collaboration, there is a 50.6% chance that the GW emitter was in the ANTARES field of view. ANTARES, being installed in the Mediterranean Deep Sea, is the largest neutrino detector in the Northern Hemisphere. It is primarily sensitive to astrophysical neutrinos in the TeV-PeV energy range. At 10 TeV, the median angular resolution for muon neutrinos is below 0.5 degrees. In the range 1-100 TeV, ANTARES has the best sensitivity to a large fraction of the Southern sky. No up-going muon neutrino candidate events were recorded within the 90% contour during a +/- 500s time-window centered on the G268556 event time. An estimate of the upper limit on the associated neutrino fluence will be sent in a subsequent circular. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20371 SUBJECT: LIGO/Virgo G268556: Swift-XRT sources DATE: 17/01/05 17:45:23 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester), J.A. Kennea (PSU), S.D. Barthelmy (NASA/GSFC), A.P. Beardmore (U. Leicester), A.A. Breeveld (UCL-MSSL), D.N. Burrows (PSU), S. Campana (INAF-OAB), S.B. Cenko (NASA/GSFC), G. Cusumano (INAF-IASF PA), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB), V.D'Elia(ASDC), N. Gehrels (NASA/GSFC), P. Giommi (ASI), C. Gronwall (PSU), H.A. Krimm (CRESST/GSFC/USRA), N.P.M. Kuin (UCL-MSSL), A.Y. Lien (GSFC/UMBC), D. Malesani (DARK/NBI), F.E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), B. Mingo (U. Leicester), J.A. Nousek (PSU), S.R. Oates (U. Warwick), P.T. O'Brien (U. Leicester), J.P. Osborne (U. Leicester), C. Pagani (U. Leicester), K.L. Page (U.Leicester), D.M. Palmer (LANL), M. Perri (ASDC), J.L. Racusin (NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU), M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB), E. Troja (NASA/GSFC/UMCP) report on behalf of the Swift team: Swift has performed a series of 291 observations of galaxies (from the GWGC catalogue) within the LVC error region for the GW trigger G268556, using the 'bayestar' GW localisation map. The observations currently span from 50 ks to 86 ks after the LVC trigger, and cover 31.3 sq degrees on the sky (corrected for overlaps). This covers 0.047 of the probability in the LVC skymap, and 0.051 of the probability in the LVC map after weighting by galaxies in the GWGC catalogue. We have detected 3 X-ray sources. Each source is assigned a rank of 1-4 which describes how likely it is to be related to the GW trigger, with 1 being the most likely and 4 being the least likely. The ranks are described at http://www.swift.ac.uk/ranks.php. We have found: * 0 sources of rank 1 * 0 sources of rank 2 * 0 sources of rank 3 * 3 sources of rank 4 For all flux conversions and comparisons with catalogues and upper limits from other missions, we assumed a power-law spectrum with NH=3e20 cm^2, and photon index (Gamma)=1.7 RANK 4 sources ============== These are catalogued X-ray sources, showing no signs of outburst compared to previous observations, so they are not likely to be related to the GW trigger. Source 1: ============= RA: 133.0839 ( = 08h 52m 20.14s) J2000 Dec: +47.5827 ( = +47d 34' 57.7") J2000 Error: +5.4 (arcsec, radius, 90% confidence). Peak Rate: 1.8e-01 +/- 6.7e-02 ct/sec (0.3-10 keV) Peak Flux: 7.9e-12 +/- 2.9e-12 erg cm^-2 s^-1 (0.3-10 keV) Cat Source: 1RXS J085218.0+473456 in the ROSAT/RASSBSC catalogue Separation: 21.8" from the XRT source Cat Rate: 6.9e-02 +/- 1.4e-02 ct/sec Cat Flux: 1.9e-12 +/- 3.8e-13 erg cm^-2 s^-1 (0.3-10 keV) so the source is 2.1-sigma above the catalogued flux. There is no evidence for fading. NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy. A SIMBAD object `[VV2006] J085220.5+473458' is 3.1" away. Source 2: ============= RA: 133.4418 ( = 08h 53m 46.03s) J2000 Dec: +47.3117 ( = +47d 18' 42.1") J2000 Error: +5.0 (arcsec, radius, 90% confidence). Peak Rate: 2.1e-01 +/- 6.8e-02 ct/sec (0.3-10 keV) Peak Flux: 9.1e-12 +/- 2.9e-12 erg cm^-2 s^-1 (0.3-10 keV) Cat Source: 1RXS J085345.1+471847 in the ROSAT/RASSBSC catalogue Separation: 10.6" from the XRT source Cat Rate: 1.8e-01 +/- 2.3e-02 ct/sec Cat Flux: 5.2e-12 +/- 6.5e-13 erg cm^-2 s^-1 (0.3-10 keV) so the source is 1.3-sigma above the catalogued flux. There is no evidence for fading. NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy. A SIMBAD object `BD+47 1620' is 2.8" away. There is 1 2MASS object within the source's 3-sigma error radius. Source 3: ============= RA: 350.3156 ( = 23h 21m 15.74s) J2000 Dec: -26.9822 ( = -26d 58' 55.9") J2000 Error: +7.6 (arcsec, radius, 90% confidence). Peak Rate: 2.6e-01 +/- 6.0e-02 ct/sec (0.3-10 keV) Peak Flux: 1.1e-11 +/- 2.6e-12 erg cm^-2 s^-1 (0.3-10 keV) Cat Source: 2RXP J232115.1-265908 in the ROSAT/ROSPSPC catalogue Separation: 15.4" from the XRT source Cat Rate: 1.9e+00 +/- 7.6e-02 ct/sec Cat Flux: 5.2e-11 +/- 2.1e-12 erg cm^-2 s^-1 (0.3-10 keV) so the source is not above the catalogued flux. There is no evidence for fading. NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy. NOTE: The source is close to a ~6 mag star (HR 8883) thus the X-ray flux may be distorted by the presence of optical photons. This circular is an official product of the Swift team. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20373 SUBJECT: LIGO/Virgo G268556: Mini-MegaTORTORA follow-up observations DATE: 17/01/05 19:24:22 GMT FROM: Sergey Karpov at Special Astrophysical Obs S.Karpov, G.Beskin (SAO RAS and Kazan Federal University, Russia), S.Bondar, E.Ivanov, E.Katkova, A.Perkov (OJS RPC PSI, Russia), A.Biryukov (SAI MSU and Kazan Federal University, Russia), V.Sasyuk (Kazan Federal University, Russia) Following GCN #20364 on the possible GW event G258556, we observed part of its sky localization region with Mini-MegaTORTORA nine-channel wide-field monitoring system (located at Special Astrophysical Observatory near Russian 6-m telescope) starting on 2017-01-04 18:32:48 UT (8.3 hours since trigger) under moderate weather conditions. The system field of view has been centered on RA, Dec = 136, 54 covering roughly 900 square degrees simultaneously. This covers about 30% of the probability in the BAYESTAR map. Coverage map of all nine channels is shown at http://mmt.favor2.info/scheduler/1416/lvc Every channel acquired 10 x 60s exposure images in white light between 2017-01-04 18:32:48 UT and 2017-01-04 18:41:50 UT. The footprints of acquired images are uploaded to GraceDB. Quick-look analysis did not reveal any transient brighter than V~14.5 magnitude in the data. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20374 SUBJECT: LIGO/Virgo G268556: Fermi-LAT search for high-energy gamma-ray counterpart DATE: 17/01/05 22:13:02 GMT FROM: Giacomo Vianello at Stanford U/Fermi LAT Giacomo Vianello (Stanford), Daniel Kocevski (NASA/MSFC), Francesco Longo (Trieste University and INFN/Trieste), Julie McEnery (NASA/GSFC), Jeremy S. Perkins (NASA/GSFC) and Judy Racusin (NASA/GSFC) report on behalf of the Fermi-LAT team: We have searched data collected by the Fermi Large Area Telescope (LAT) for possible high-energy (E > 100 MeV) gamma-ray emission in spatial/temporal coincidence with the LIGO/Virgo trigger G268556. Fermi/LAT had an instantaneous coverage of ~55% at the time of the trigger (T0 = 2017-01-04 10:11:59 UTC), and reached 100% cumulative coverage within 5 ks. We define "instantaneous coverage" as the integral over the region of the LIGO probability map that is within the LAT field of view at a given time, and "cumulative coverage" as the integral of the instantaneous coverage over time. We performed a search for a transient counterpart within the 90% contour of the LIGO Bayestar map on the time window from T0 to T0 + 10 ks and found no significant excess. The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20375 SUBJECT: LIGO/Virgo G268556: AGILE MCAL and Super-AGILE Observations DATE: 17/01/05 22:51:15 GMT FROM: Francesco Verrecchia at ASDC, INAF-OAR M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A. Ursi (INAF/IAPS), F. Fuschino (INAF/IASF-Bo), Y. Evangelista, I. Donnarumma (INAF/IAPS), F. Verrecchia (ASDC and INAF/OAR), G. Minervini (INAF/IAPS), M. Marisaldi (INAF/IASF-Bo and Bergen University), A. Bulgarelli, A. Zoli (INAF/IASF-Bo), C. Pittori, F. Lucarelli (ASDC and INAF/OAR), G. Piano, P. Munar-Adrover, A. Argan (INAF/IAPS), M. Cardillo (INAF/OA-Arcetri and INAF/IAPS), A. Giuliani (INAF/IASF-Mi), M. Pilia, A. Trois (INAF/OA-Cagliari), F. Longo (Univ. Trieste and INFN Trieste) report on behalf of the AGILE Team: In response to the LIGO/Virgo GW event G268556 at T0 = 2017-01-04 10:11:58.599 UTC, a preliminary analysis of the AGILE-GW data processing procedure identified a Mini-Calorimeter (MCAL) data acquisition within the time interval close to T0. The MCAL full telemetry acquisition (following an internal trigger) started at T1 = 10:11:47.397 UTC and ended at T2 = 10:11:59.997 UTC. The acquisition lasted 12.6 sec and included the T0 time of interest. An analysis of these data does not reveal any significant transient event in the energy range 0.4-100 MeV. Three-sigma upper limits (UL) are obtained for a 1 s integration time at different celestial positions within the accessible G268556 localization region, from a minimum of 5.45e-7 erg cm^-2 to a maximum of 6.18e-7 erg cm^-2, in the 400-10000 keV energy range. The AGILE-MCAL detector has a full solid angle acceptance, and is operational in the range 0.4 - 100 MeV. The MCAL current trigger rate is on average ~ 0.15 every 20 sec. The Super-Agile (SA) detector had a partial coverage of the G268556 localization region at T0 (within 1s), that was observed between 0 and 30 deg off-axis. No significant detection was obtained in the SA light curve (20-60 keV), for a stable background within +/-100s from T0. The 3-sigma UL has been derived for a 1 s integration time, and varies between 1.5e-8 erg cm^-2 (for an on-axis position) and 6.6e-8 erg cm^-2 (for a 30 degrees off-axis position). SA is an X-ray coded mask instrument with 40x40 deg field of view at half-sensitivity. Furthermore, a search in the AGILE anticoincidence (AC) and GRID ratemeters data did not produce any significant detection. The GRID large-FoV (2.5 sr) imaging instrument had exposure near T0 for a significant fraction of the G268556 localization region. The GRID data analysis in the energy range 30 MeV - 10 GeV is in progress, and the results will be reported in a following GCN. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20376 SUBJECT: LIGO/Virgo G268556: DESGW/DECam observations DATE: 17/01/05 23:14:01 GMT FROM: M. Soares-Santos at Fermi Lab M. Soares-Santos (Fermilab), J. Annis (Fermilab), E. Berger (Harvard) D. J. Brout (UPenn), R. Butler (Fermilab), H.-Y. Chen (UChicago), P. Cowperthwaite (Harvard), H. T. Diehl (Fermilab), Z. Doctor (UChicago), B. Farr (UChicago), D. Finley (Fermilab), R Foley, W-F Fong (Arizona), J. Frieman (UChicago), M. Garcia-Belido (CIEMAT/Madrid), R. Gruendl (NCSA), K. Herner (Fermilab), D. Holz (UChicago), R. Kessler (UChicago), E. Neilsen (Fermilab), A. Palmese (UCL), M. Sako (UPenn), B. Yanny (Fermilab) On behalf of the DECam GW follow-up team and the DESGW team: We report on observations of LVC trigger G268556 conducted with the Dark Energy camera (DECam) on the Blanco telescope at CTIO as part of NOAO program 2016B-0124 (PI: Berger). The observations commenced on 2017-01-05 01:34:45 UT (15 hours following the GW detection), and consisted of 90-sec exposures in i-band. We observed about 10% of the localization probability map in 4h of observing time, covering 230 sq. deg. to a 5-sigma point source limiting magnitude of i~23 AB mag. Coordinates are given below. Analysis is underway. radec 0.430246 -35.4841 358.640221 -34.45238 4.146646 -37.5131 14.386904 -42.5855 355.722346 -33.4384 2.265329 -36.4986 16.634896 -43.5999 355.386617 -31.41045 6.077717 -38.5275 353.648446 -32.42443 0.096254 -37.5131 357.452083 -32.42443 12.230792 -39.542 12.212492 -41.571 358.27245 -36.48033 18.7554 -42.5855 8.062783 -39.542 1.970025 -38.5275 16.510696 -41.571 10.106204 -40.5565 18.962325 -44.6144 5.874796 -40.5565 10.018408 -42.5855 12.1923 -43.5999 14.3376 -40.5565 3.894796 -39.542 21.375646 -45.6289 21.375646 -45.6289 4.374242 -35.4841 21.0774 -43.5999 10.185421 -38.5275 7.914283 -41.571 2.53245 -34.4696 23.482921 -44.6144 14.441625 -44.6144 25.97865 -45.6289 23.882129 -46.6434 8.196946 -37.5131 6.261133 -36.4986 16.772746 -45.6289 18.568996 -40.5565 16.398796 -39.542 53.652854 -47.6579 25.519996 -43.5999 32.378042 -46.6434 19.192333 -46.6434 55.827133 -46.6434 20.808883 -41.571 27.492404 -42.5855 29.962592 -43.5999 28.003529 -44.6144 58.434467 -47.6579 30.305954 -45.6289 28.572029 -46.6434 36.758192 -48.6723 37.067833 -46.6434 33.226408 -42.5855 39.308158 -47.6579 57.923654 -45.6289 60.517033 -46.6434 48.871258 -47.6579 34.908854 -45.6289 29.744954 -47.6579 23.123908 -42.5855 25.107092 -41.571 51.137342 -46.6434 53.32065 -45.6289 46.447529 -46.6434 46.5153 -48.6723 59.948521 -44.6144 51.3939 -48.6723 34.526567 -47.6579 31.879696 -48.6723 26.489458 -47.6579 32.824725 -44.6144 60.393646 -37.5131 44.089667 -47.6579 -- Marcelle Soares-Santos http://home.fnal.gov/~marcelle/ http://www.darkenergysurvey.org/ //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20377 SUBJECT: LIGO/Virgo G268556: ATLAS imaging of the skymap DATE: 17/01/05 23:24:44 GMT FROM: S. J. Smartt at Queens U Belfast J. Tonry, L. Denneau, A. Heinze, B. Stalder, H. Weiland (IfA), C. W. Stubbs (Harvard), K. W. Smith, S. J. Smartt, (QUB), D. R. Young (QUB), A. Rest (STScI), K. C. Chambers (IfA), M. Coughlin (Harvard), M. E. Huber (IfA), D. E. Wright (QUB), H. Flewelling, E. A. Magnier, A. S. B. Schultz, C. Waters, R. J. Wainscoat (IfA) We report the following observations of the skymap for LIGO/Virgo G268556 with the ATLAS telescope system ATLAS is a twin 0.5m telescope system on Haleakala and Mauna Loa (see Tonry et al. ATel 8680 and Tonry 2011, PASP, 123, 58). The first unit is operational on Haleakala and is robotically surveying the sky in two filters cyan and orange (denoted c and o, all mags are in AB system). More information is on http://www.fallingstar.com The alert for G268556 was received 6.5 hours after the event, too close to sunrise for targeted observations on 57757 in Hawaii. The next night we started observing the LIGO/VIRGO localisation region at 57758.296 (2016-01-05.296 UT) starting at a pointing centre of RA=80, DEC=-30, moving north and east across the lobe to RA=170,80. A total of 1250 square degrees were covered. Sets of dithered 8x30sec exposures in the cyan filter were taken, at a 5-sigma sensitivity of c = 19.0 for each exposure. Difference images are automatically created with a reference image built during early 2016. These data are currently being processed and results will be reported soon. Maps will be uploaded to GraceDB. During the previous night (2016-01-04 UT) ATLAS did its routine survey of a 20 degree wide declination strip between RA = 334 to 213 deg (wrapped through 0), and DEC = +15 to +35 deg. This intersected a small part of the LIGO/VIRGO map (containing 9% of the probability) between 30mins to 3hrs after the detection time of G268556. ATLAS also surveyed this strip four days prior on 57753, but the sky was partly cloudy. No obvious transient is visible in this 9% region. Furthermore, ATLAS has been scanning the northern region containing the highest probability contours during the last three weeks. We report here bright transients found before the detection of G268556. They will mostly be still visible on the sky map region, but are mostly field supernovae (or CVs) and unrelated to the GW source. IAU Name | ATLAS Name | RA (J2000) | Dec (J2000) | Disc. MJD | Disc. Date | Disc Mag | Notes AT2016iyx | ATLAS16dzp | 08:43:24.74 | +37:32:45.8 | 57742.47 | 20161220.47 | 17.28 o | SN2016izg | ATLAS16eak | 07:53:12.77 | +12:53:56.4 | 57736.47 | 20161214.47 | 17.10 o | ASASSN-16pb (Ia) AT2016izk | ATLAS16eaw | 08:49:04.77 | +14:24:49.8 | 57744.57 | 20161222.57 | 16.62 c | ASASSN-16pc (CV) AT2016jae | ATLAS16eay | 09:42:34.50 | +10:59:35.3 | 57744.61 | 20161222.61 | 17.42 c | AT2016jax | ATLAS16ecb | 08:32:53.76 | +42:08:01.6 | 57746.49 | 20161224.49 | 17.60 c | AT2016jaw | ATLAS16ecc | 08:48:21.88 | +24:31:51.9 | 57745.52 | 20161223.52 | 17.98 c | | ATLAS16ecj | 08:50:02.45 | +46:39:49.0 | 57742.48 | 20161220.48 | 18.50 o | | | ATLAS17aay | 09:34:07.69 | +31:46:25.4 | 57745.55 | 20161223.55 | 18.44 c | | //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20381 SUBJECT: LIGO/Virgo G268556/GW170104: Global MASTER Net observations and first OT detection DATE: 17/01/06 15:03:24 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.M. Lipunov, N.Tyurina, E. Gorbovskoy, V.G. Kornilov, P.Balanutsa, A.Kuznetsov, V.Shumkov, M.I.Panchenko Lomonosov Moscow State University, Sternberg Astronomical Institute D.Buckley, S. Potter, M. Kotze South African Astronomical Observatory R. Rebolo, M. Serra-Ricart, G. Israelian, N.Lodiu The Instituto de Astrofisica de Canarias A. Tlatov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory N.M. Budnev, O. Gress, K. Ivanov Irkutsk State University V.Yurkov, Yu.Sergienko, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk Global MASTER Net was starting observations of the LIGO/Virgo G268556 error field at 2017-01-04 15:46:07 UT during regular sky survey up to 20 unfiltered magnitude. After received alert circular (Shawhan et al.,20364) we started special inspection with MASTER-Amur, MASTER-Tunka, MASTER-Kislovodsk, MASTER-OAFA and MASTER-SAAO telescopes. We cover 50.2% initial probability now up to 20.5 mag. The first OT MASTER OT J090021.21+635049.7 detection ( Possible SN in 1.797" from Sloan galaxy). MASTER-Kislovodsk auto-detection system discovered OT source at (RA, Dec) = 09h 00m 21.21s +63d 50m 49.7s on 2017-01-05.06666 UT. The OT unfiltered magnitude is 18.6m+-0.2 (limit 19.9m). The OT is seen in 4 image. We have reference image without OT on 2012-10-20.91652 UT with unfiltered magnitude limit 19.7m. No known minor planets, brighter than V = 21.0, were found in the 15.0-arcminute region around R.A. = 09 00 21.21, Decl. = +63 50 49.7 (J2000.0) on 2017 01 05.07 UT . OT is offset 1.79709" from the Sloan galaxy rmag=19.96, gmag=20.64 http://skyserver.sdss.org/dr9/en/tools/chart/navi.asp?ra=135.08928453&dec=63.84745156 Spectral and photometrical observations are required . The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/090021.21635049.7.png //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20382 SUBJECT: SUBJECT: LIGO/Virgo G268556: ATLAS17aeu - an unusual transient within the skymap DATE: 17/01/06 19:09:41 GMT FROM: S. J. Smartt at Queens U Belfast J. Tonry, L. Denneau, A. Heinze, B. Stalder, H. Weiland (IfA), C. W. Stubbs (Harvard), K. W. Smith, S. J. Smartt, (QUB), D. R. Young (QUB), A. Rest (STScI), K. C. Chambers (IfA), M. Coughlin (Harvard), M. E. Huber (IfA), D. E. Wright (QUB), H. Flewelling, E. A. Magnier, A. S. B. Schultz, C. Waters, R. J. Wainscoat (IfA) Following on from GCN 20377, we have processed the ATLAS data beginning at 57758.296 (2016-01-05.296 UT) which started at a pointing centre of RA=80, DEC=-30, and moved north and east across the northern sky lobe to RA=170,80. We find one transient that appears to be new (and recovered old ones). This object has some unusual characteristics that warrant further attention ATLAS17aeu 09:13:13.89 +61:05:33.6 (138.30789 +61.09267) J2000 The position is within the inner 16% probability contour. This object is not spatially coincident with any star or host galaxy. The lightcurve faded by 0.85 mag over 1.176hrs MJD c mag err 57758.4129676 18.05 0.09 57758.4144595 18.18 0.1 57758.4267173 18.22 0.1 57758.4419066 18.58 0.13 57758.4469072 18.45 0.11 57758.4479226 18.34 0.11 57758.454986 18.39 0.11 57758.4619614 18.90 0.18 (the cyan mag is effectively an average of g and r). The object has now fallen below the detection limit (orange filter; o ~ 19) on the night of 57759. Such a fast fade is unusual if the object is extragalactic. The obvious immediate explanations for this object are 1) It is not a real astrophysical transient. We consider this unlikely. 2) The photometric errors are under-estimated and it is flat. We consider this unlikely, and the errors to be reliable. 3) It is a Galactic CV. But the fading is too fast for typical CVs. 4) It is an M-dwarf flare. But the fading is slow for a typical M-dwarf (which are usually between 2 and >5 mags per hour) We note that there is no faint point source in the Pan-STARRS 3Pi stacked sky (Chambers et al. 2017, arXiv:1612.05560, and http://panstarrs.stsci.edu). There is no counterpart in the MPC, Vizier, WISE, various CV and stellar catalogues. The object is 23 arcsec from the galaxy SDSS J091312.36+610554.2 which has a spectroscopic redshift of z = 0.199 +/- 0.00004. This implies a luminosity distance of 990 Mpc (for Ho=69). If ATLAS17aeu is related, it would be at a projected distance of 75kpc from the Galaxy. This luminosity distance is consistent with the BAYESTAR 3D volume rendering (Singer et al. 2016, ApJ 829, L1) of G268556 which suggests a 10-90 percentile probability of 520-1010 Mpc in this direction. If it were associated with the z = 0.199 +/- 0.00004 galaxy, then it would be unusually luminous (M_g ~ -21.5). While a Galactic origin is still the most probable, it remains to be confirmed. We encourage a search of any contemporaneous data taken at the same time we detected this object and deep imaging of the position to recover any host object (star or galaxy). //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20383 SUBJECT: LIGO/Virgo G268556: Pan-STARRS1 observations of the skymap DATE: 17/01/06 20:08:36 GMT FROM: S. J. Smartt at Queens U Belfast K. C. Chambers (IfA), K. W. Smith (QUB), M. E. Huber (IfA), S. J. Smartt, D. R. Young, D. E. Wright (QUB), M. Coughlin (Harvard), L. Denneau, H. Flewelling, A. Heinze, E. A. Magnier (IfA), A. Rest (STScI), B. Stalder (IfA), A. S. B. Schultz, C. W. Stubbs (Harvard) J. Tonry, C. Waters, R. J. Wainscoat, H. Weiland (IfA) We report observations of the localisation skymap for LIGO/Virgo G268556 with the Pan-STARRS1 telescope (see Chambers et al. arXiv:1612.05560) and our search for transients (Smartt et al. 2016, MNRAS, 462, 4094). The alert for G268556 came too close to sunrise for immediate observations at the time of the event release and we started observing the LIGO/VIRGO localisation region at 57758.309 (2017-01-05 07:34:57 UT), beginning at RA=114 DEC=+5 and scanning the error lobe north and eastwards to approximately R=140, DEC=+65. A plot of the footprints has been uploaded to GraceDB. The images were taken in the Pan-STARRS i-band in a series of overlapping 45s exposures, with typically 4 images at each position. These were combined into stacks and subtracted from the Pan-STARRS1 3Pi reference image (as discussed in Chambers et al. arXiv:1612.05560, and available at http://panstarrs.stsci.edu). The combined images typically reach i~21. We have located several tens of transient candidates and will report these in a GCN after a further nights observing on 57759, and confirmation of stationary sources. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20384 SUBJECT: LIGO/Virgo G268556: HAWC follow-up of northern sky DATE: 17/01/06 20:34:07 GMT FROM: Joshua Wood at UW-Madison J. Wood (UW-Madison) and I. Martinez (UMD) report on behalf of the HAWC Collaboration: The northern portion of the reported LIGO error region was within the HAWC field-of-view at the time of LVC trigger G268556. HAWC was operating and our real-time all-sky GRB monitoring analysis was running at this time. This analysis searches for excess counts over the steady-state cosmic-ray background using 4 sliding time windows (0.1, 1, 10, and 100 seconds) shifted forward in time by 10% their width over the course of the entire day. Within each time window, we search the HAWC sky within 50 degrees of zenith using 2.1 deg x 2.1 deg square bins shifted by ~0.1 deg along the directions of Right Ascension and Declination. This analysis is tuned for detecting ~100 GeV photons and is sensitive to the most fluent GRBs. It did not report any significant post-trials events near the time of gravitational-wave trigger G268556. On 2017/01/05 we went back and re-analyzed the data within +/- 60 seconds of gravitational-wave trigger G268556 on 3 timescales (1, 10, 100 sec) to look for excesses consistent with the latest LIGO map. None were found. As a complementary analysis we integrated the ~2 hours following the trigger time. This corresponds to the time interval when the searched region (90% probability contour) stayed in our field-of-view. The analysis performed on this data set is sensitive to ~0.5-100TeV. We found no significant excess. HAWC is a TeV gamma ray water Cherenkov array located in the state of Puebla, Mexico that monitors 2/3 of the sky every day with an instantaneous field of view of ~2 sr. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20385 SUBJECT: LIGO/Virgo G268556: Updated sky map from gravitational-wave data DATE: 17/01/06 21:44:29 GMT FROM: Giuseppe Greco at U degli Studi di Urbino The LIGO Scientific Collaboration and Virgo report: We have re-analyzed LIGO data around the time of the compact binary coalescence (CBC) event candidate G268556 (GCN 20364) taking into account our current understanding of calibration uncertainties. Although a full recalibration remains to be done, we expect that this event will be confirmed with a false alarm rate (FAR) of less than 1 per 100 years. Parameter estimation has been performed using LALInference (Veitch et al., PRD 91, 042003) and a new sky map, LALInference_skymap.fits.gz, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/events/G268556 This is the preferred sky map at this time. This map has two arcs in nearly the same positions as the original BAYESTAR sky map but the probability is divided more equally between the northern and southern arcs. The 50% and 90% credible regions span about 500 deg2 and 2000 deg2, respectively, which are somewhat larger than the initial BAYESTAR sky map due to marginalizing over calibration uncertainties. We will recalculate the sky map once the full recalibration is complete and will share it at that time, but that is likely at least a few weeks away. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20386 SUBJECT: LIGO/Virgo G268556/GW170104: Asiago Observations DATE: 17/01/06 23:46:03 GMT FROM: Andrea Melandri at INAF-OAB M. Berton, G. La Mura, S. Chen (DFA-UNiPd), L. Tomasella, E. Cappellaro (INAF-OAPD), A. Melandri (INAF-OAB), S. Piranomonte (INAF-OAR), G. Greco (Urbino University/INFN Firenze), P. D'Avanzo (INAF-OAB), G. Stratta (Urbino University/INFN Firenze), S. Ascenzi (INAF-OAR), M.T. Botticella (INAF-OAC), V. D’Elia (INAF-ASDC), E. Palazzi (INAF-IAFS Bo), A. Rossi (INAF-IASF Bo), S. Covino (INAF-OAB), L.Amati (INAF-IASF Bo), L. A. Antonelli, (INAF-OAR), M. Branchesi (Urbino University/INFN Firenze), S. Campana (INAF-OAB), F. Getman (INAF-OAC), A. Grado (INAF-OAC), L. Limatola (INAF-OAC), M. Lisi (INAF-OAR), L. Nicastro (INAF-IASF Bo), E. Pian (SNS-Pisa), L. Pulone (INAF-OAR), G. Tagliaferri (INAF-OAB), V. Testa (INAF-OAR), S. Yang (INAF-OAPD), E. Brocato (INAF-OAR) on behalf of GRavitational Wave Inaf TeAm report: The transient MASTER OT J090021.21+635049.7 (GCN 20381) was observed with the Asiago 1.82m Copernico telescope equipped with the AFOSC camera on 2017-01-06.883 UT. The noisy spectrum shows a broad P-Cygni like feature with the absorption centred at 674nm. The best fit with SNID (Blondin and Tonry 2007, ApJ, 666, 1024) is with a type Ia SN near maximum at a redshift ~0.10. The transient has an apparent magnitude V~19.4, that would indicate an absolute magnitude -18.9, fully consistent with the spectroscopic classification. However, we notice that this is inconsistent with the photometric redshift of the host galaxy listed in SDSS-DR13 (z=0.245). We also obtained a 15 min r-band exposure centred on the unusual transient ATLAS17aeu 09:13:13.89 +61:05:33.6 (GCN20382) on 2017-01-06.913 UT. No source was detected with an upper limit r~21.7 (2.5 sigma). //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20388 SUBJECT: LIGO/Virgo G268556: SWASP optical imaging DATE: 17/01/07 09:54:03 GMT FROM: Danny Steeghs at U of Warwick/GOTO D. Steeghs, D.Pollacco, K.Ulaczyk, R.Cutter, R.West, A.Levan (U. Warwick), D. Galloway, E.Rol, E.Thrane (Monash U.), V. Dhillon, M.Dyer, S.Littlefair, E.Daw, J.Mullaney (U. Sheffield), G. Ramsay (Armagh O.), P. O'Brien, R. Starling (U. Leicester) On behalf of the GOTO collaboration: We report on optical observations with the SuperWASP Exoplanet camera array on La Palma, in response to GCN #20364. Targeted observations containing ~45% of the BAYESTAR source location probability were performed between 21:47 UT Jan 4 2017 and 06:20 UT Jan 5 2017. Each pointing consisted of 3x30s exposures in the clear filter and fields were repeated between 20 and 35 times during that observing window. These regions were also observed as part of a survey mode program the night before with 2x30s exposures at each position between 4:37 and 6:35 UT Jan 4 2017 (4-6 hours before the event). Considering the updated LALInference map (GCN #20385), our pointings cover 40% of the total probability. Conditions were not photometric with some variable thin clouds present. Typically a (5 sigma) photometric depth equivalent to V~15 was achieved per 3x30s pointing. Analysis is ongoing and notable source detections will be reported in a future circular. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20390 SUBJECT: LIGO/Virgo G268556: Swift-XRT detection of ATLAS17aeu DATE: 17/01/07 13:33:36 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester), J.A. Kennea (PSU), S.D. Barthelmy (NASA/GSFC), A.P. Beardmore (U. Leicester), A.A. Breeveld (UCL-MSSL), D.N. Burrows (PSU), S. Campana (INAF-OAB), S.B. Cenko (NASA/GSFC), G. Cusumano (INAF-IASF PA), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB), V.D'Elia(ASDC), N. Gehrels (NASA/GSFC), P. Giommi (ASI), C. Gronwall (PSU), H.A. Krimm (CRESST/GSFC/USRA), N.P.M. Kuin (UCL-MSSL), A.Y. Lien (GSFC/UMBC), D. Malesani (DARK/NBI), F.E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), B. Mingo (U. Leicester), J.A. Nousek (PSU), S.R. Oates (U. Warwick), P.T. O'Brien (U. Leicester), J.P. Osborne (U. Leicester), C. Pagani (U. Leicester), K.L. Page (U.Leicester), D.M. Palmer (LANL), M. Perri (ASDC), J.L. Racusin (NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU), M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB), E. Troja (NASA/GSFC/UMCP) report on behalf of the Swift team: Swift has performed a targetted observation of the interesting transient ATLAS17aeu (Tonry et al., LVC Circ. 20382). The observations ran from 00:00 UT to 01:37 UT on 2017 Jan 7, and contained 1.4 ks of cleaned PC mode data. A faint, uncatalouged X-ray source is found at RA, Dec = 138.3059, +61.0919 degrees, which corresponds to: RA (J2000): 09h 13m 13.42s Dec (J2000): +61d 05' 30.8") with an uncertainty of 6.3 arcsec (radius, 90% confidence). This is 4.1" from the position of ATLAS17aeu, consitent with that object. This source ("source5" of the XRT follow up of G268556) has a 0.3-10 keV count rate of 7.2 (+/-2.9) ×10^-3 ct s^-1, corresponding to a 0.3-10 keV flux of 3.1 (+/-1.2) ×10^-13 erg cm^-2 s^-1, assuming a power-law spectrum with Gamma=1.7 and NH=3e20 cm^-2. This is below the upper limit derived from the RASS at the source location. This source has not been previously observed by public XMM data, or Swift observations. At the present time we cannot ascertain whether the source is variable, but follow up in encouraged. A second, catalogued ("rank 4") source is also detected in our observations. Details of both sources are below. For all flux conversions and comparisons with catalogues and upper limits from other missions, we assumed a power-law spectrum with NH=3e20 cm^2, and photon index (Gamma)=1.7 RANK 3 sources ============== These are uncatalogued X-ray sources, however they are not brighter than previous upper limits, so do not stand out as likely counterparts to the GW trigger. Source 5: ============= RA: 138.3059 ( = 09h 13m 13.42s) J2000 Dec: +61.0919 ( = +61d 05' 30.8") J2000 Error: +6.3 (arcsec, radius, 90% confidence). Peak Rate: 7.2e-03 +/- 2.9e-03 ct/sec (0.3-10 keV) Peak Flux: 3.1e-13 +/- 1.2e-13 erg cm^-2 s^-1 (0.3-10 keV) RASS UL: 1.8e-02 ct/sec, 3-sigma, converted to XRT (0.3-10 keV) so the source is not above the RASS 3-sigma upper limit. There is no evidence for fading. NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy which is consistent (within 3-sigma) with the distance to the GW object. RANK 4 sources ============== These are catalogued X-ray sources, showing no signs of outburst compared to previous observations, so they are not likely to be related to the GW trigger. Source 4: ============= RA: 138.0838 ( = 09h 12m 20.11s) J2000 Dec: +60.9299 ( = +60d 55' 47.6") J2000 Error: +5.1 (arcsec, radius, 90% confidence). Peak Rate: 1.6e-02 +/- 4.4e-03 ct/sec (0.3-10 keV) Peak Flux: 6.7e-13 +/- 1.9e-13 erg cm^-2 s^-1 (0.3-10 keV) Cat Source: 1RXS J091222.2+605603 in the ROSAT/RASSFSC catalogue Separation: 22.1" from the XRT source Cat Rate: 2.5e-02 +/- 9.4e-03 ct/sec Cat Flux: 7.1e-13 +/- 2.6e-13 erg cm^-2 s^-1 (0.3-10 keV) so the source is not above the catalogued flux. There is no evidence for fading. NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy which is consistent (within 3-sigma) with the distance to the GW object. A SIMBAD object `2MASS J09122029+6055503' is 3.1" away. There is 1 2MASS object within the source's 3-sigma error radius. This circular is an official product of the Swift team. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20392 SUBJECT: LIGO/Virgo G268556/GW170104: Global MASTER Net second OT detection DATE: 17/01/07 14:57:28 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.M. Lipunov, O.Gress, N.Tyurina, E. Gorbovskoy, V.G. Kornilov, P.Balanutsa, A.Kuznetsov, V.Shumkov, M.I.Panchenko Lomonosov Moscow State University, Sternberg Astronomical Institute D.Buckley, S. Potter, M. Kotze South African Astronomical Observatory R. Rebolo, M. Serra-Ricart, G. Israelian, N.Lodiu The Instituto de Astrofisica de Canarias A. Tlatov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory N.M. Budnev, O. Gress, K. Ivanov Irkutsk State University V.Yurkov, Yu.Sergienko, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk MASTER OT J105811.78+811432.6 discovery - BLA flare in GW170401 field MASTER-Kislovodsk auto-detection system discovered OT source at (RA, Dec) = 10h 58m 11.78s +81d 14m 32.6s on 2017-01-06.74507 UT. The OT unfiltered magnitude is 16.1m (limit 19.4m). The OT is seen in 11 images. There is no minor planet at this place. We have reference image without OT on 2012-10-20.65339 UT with unfiltered magnitude limit 19.7m. There is Blazar with gamma-ray counterpart in 0.57" ( http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=&-out.add=_r&-out.add=_RAJ%2C_DEJ&-sort=_r&-to=&-out.max=20&-meta.ucd=2&-meta.foot=1&-c=164.5490875+81.242377777778&-c.rs=5 ) Spectral observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/MASTEROTJ105811.78+811432.jpg //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20393 SUBJECT: LIGO/Virgo G268556: Palomar 200-inch detects ATLAS17aeu, possible afterglow of GRB070105A? DATE: 17/01/07 16:44:34 GMT FROM: Mansi M. Kasliwal at Caltech M. M. Kasliwal (Caltech), S. M. Adams (Caltech), H. Vedantham (Caltech), V. Bhalerao (IUCAA), S. B. Cenko (NASA/GSFC), R. Quimby (SDSU) report on behalf of the GROWTH (Global Relay of Observatories Watching Transients Happen) and iPTF (intermediate Palomar Transient Factory) collaborations We observed the position of the fast-fading ATLAS17aeu (Tonry et al. LVC GCN#20382) with the Large Format Camera on the Palomar 200-inch Hale Telescope. At 2017-01-07 08:05:33 UTC, we found that ATLAS17aeu had faded further to i=21.9 +/- 0.3 mag (AB mags, calibration wrt SDSS). If we fit a power law to the decay, the best-fit slope is 1.1 +/- 0.2 and best-fit t_zero is 57758.322 +/- 0.043 (i.e. 21.5 hr after GW trigger, LVC GCN#20364). We caution that we have not corrected for the filter differences between ATLAS and LFC. Incidentally, this t_zero is consistent with GRB070105A reported by POLAR (GCN#20387) and detected by ASTROSAT (GCN#20389). The hypothesis that this is the afterglow of the GRB appears consistent with the X-ray detection reported by Swift (Evans et al. LVC GCN#20390). //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20394 SUBJECT: LIGO/Virgo G268556: EWE001 and EWE002- two events close to GCN 20382 with the skymap DATE: 17/01/07 16:59:58 GMT FROM: Jinzhong Liu at Xinjiang Astronomical Observatory Liu, Jinzhong (XAO); Xu,dong (NAOC); Zhang, Yu (XAO); Zhang, Xuan (XAO); Niu, Hubiao (XAO); Pu, guangxin (XAO); Ma, shuguo (XAO); Yang, taozhi (XAO); Song, fangfang(XAO), on behalf of the NOWT group report: We are following up the GraceDB event (event UID: G268556) with Nanshan One-meter Wide field Telescope (NOWT) from Xinjiang Astronomical observatory (XAO). V band with 180s is used during this survey observation, and the maximum probability northern-skymap (Submitted by GraceDB Processor on Jan 4, 2017 3:07:44 PM) with 100 square degree is covered. By cross-certification using the UCAC3 catalogue, here we reported two new transients close to Tonry et al., (LVC Circ. 20382) with 35", which were named as EWE001 and EWE002. EWE001: HJD RA(Deg.) DEC(Deg.) V_mag M_err 2457761.12729148 138.30136 61.098523 15.024 0.086 EWE001: HJD RA(Deg.) DEC(Deg.) V_mag M_err 2457761.12729148 138.32121 61.098307 14.090 0.039 Analysis and survey are ongoing. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20395 SUBJECT: LIGO/Virgo G268556: AGILE-GRID preliminary analysis DATE: 17/01/07 17:24:45 GMT FROM: Francesco Verrecchia at ASDC, INAF-OAR M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), F. Verrecchia (ASDC and INAF/OAR), G. Minervini (INAF/IAPS), A. Giuliani (INAF/IASF-Mi), A. Bulgarelli, A. Zoli (INAF/IASF-Bo), C. Pittori (ASDC and INAF/OAR), I. Donnarumma, P. Munar-Adrover, G. Piano (INAF/IAPS), F. Lucarelli (ASDC and INAF/OAR), M. Cardillo (INAF/OA-Arcetri and INAF/IAPS), F. Longo (Univ. Trieste and INFN Trieste), A. Ursi (INAF/IAPS), F. Fuschino (INAF/IASF-Bo), Y. Evangelista (INAF/IAPS), M. Marisaldi (INAF/IASF-Bo and Bergen University)(INAF/IAPS), A. Argan (INAF/IAPS), M. Pilia, A. Trois (INAF/OA-Cagliari), V. Fioretti (INAF/IASF-Bo), report on behalf of the AGILE Team: In response to the LIGO/Virgo GW trigger G268556 (Shawhan et al., GCN #20364) we performed an analysis of the AGILE Gamma-Ray Imaging Detector (GRID) data on different timescales. On LIGO trigger time (T0), the GRID exposure covered about 40% of the LIGO localization region; this region was observed with off-axis angles between 0 and 70 deg. An analysis of the data in the energy range 30 MeV - 10 GeV was performed on timescales from 2 to 1000 sec centered at T0. Typical 3-sigma preliminary upper limits (UL) obtained within the accessible G268556 localization region are reported below: 2.0e-06 erg cm^-2 s^-1 for integration time of 2s, 3.4e-08 erg cm^-2 s^-1 for integration time of 100s. These measurements were obtained with AGILE observing a large portion of the sky in spinning mode. Additional GRID data analysis on longer time intervals is in progress. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20396 SUBJECT: LIGO/Virgo G268556: VLA follow-up of ATLAS17aeu DATE: 17/01/08 02:20:50 GMT FROM: Alessandra Corsi at Texas Tech U. A. Corsi (TTU), M.M. Kasliwal (CalTech), D.A. Frail (NRAO), and N.T. Palliyaguru (TTU) report: We observed the position of the fast-fading ATLAS17aeu (Tonry et al. LVC GCN#20382) located in the error region of LIGO/Virgo G268556 (LVC GCN#20364) with the Karl G. Jansky Very Large Array (VLA) in its A configuration. The observations started on 2017-Jan-07 14:06:40 UT, ended on 2017-Jan-07 15:06:29 UT, and were carried out in C-band (central frequency of about 6 GHz). A provisional reduction of our data shows a radio source located at the position of ATLAS17aeu. For this source, we measure a radio flux of (159.0+/-9.8) uJy at 6.2 GHz. We note that the broad-band detection (radio, optical, and X-rays) of ATLAS17aeu is consistent with a GRB afterglow hypothesis (see Evans et al. LVC GCN#20390 and Kasliwal et al. LVC GCN#20393). Further observations are planned. We thank the VLA staff for rapidly executing these observations. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20397 SUBJECT: Discovery Channel Telescope Imaging of ATLAS17aeu (LVCG268556) DATE: 17/01/08 02:34:11 GMT FROM: Brad Cenko at NASA/GSFC S. B. Cenko and E. Troja (NASA Goddard Space Flight Center) report on behalf of a larger collaboration: We imaged the location of ATLAS17aeu (Tonry et al., LVC Circ. 20382) with the Large Monolithic Imager (LMI) on the 4.3 m Discovery Channel Telescope in Happy Jack, AZ. Observations were obtained in the g, r, and i filters beginning at 10:56 UT on 2017 January 7 (dt ~ 3.0 d after the GW trigger time). The optical source is clearly detected in all three filters, with the following AB magnitudes (see also Kasliwal et al., LVC Circ. 20393) g = 22.45 +/- 0.05 r = 22.08 +/- 0.05 i = 21.96 +/- 0.05 The resulting SED is reasonably well fit by a power-law (fnu ~ nu^-alpha) with alpha ~ 0.9. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20398 SUBJECT: LIGO/Virgo G268556: iPTF Optical Transient Candidates DATE: 17/01/08 02:57:57 GMT FROM: Mansi M. Kasliwal at Caltech M. M. Kasliwal (Caltech), L. P. Singer (NASA/GSFC), E. Karamehmetoglu (OKC), S. B. Cenko (NASA/GSFC), R. Quimby (SDSU), D. Cook (Caltech), T. Barlow (Caltech), V. Bhalerao (IUCAA), J. Rana (IUCAA), A. Goobar (OKC), J. Sollerman (OKC), R. Amanullah (OKC), Y. Cao (UW Seattle), A. A. Miller (Northwestern/Adler) report on behalf of the iPTF and GROWTH collaborations: We have performed tiled observations of LIGO/Virgo G268556 (LVC, GCN 20364) using the Palomar 48-inch Oschin telescope (P48). Due to weather, our observations only began on 2017-01-07 UTC. The northern probability island from the updated LALInference localization (LVC, GCN 20385) was observable from Palomar for most of the night. Starting at 13:03 UT (2.88 d after the LIGO trigger), we imaged 85 of the fields two or more times, spanning 622 square degrees. We estimate a 32% prior probability that these fields contain the true location of the source. During preliminary sifting through candidate variable sources using image subtraction by both our IPAC pipeline (Masci et al. 2016) and NERSC pipeline (Cao et al. 2016), and applying standard iPTF vetting procedures, we flagged the following optical transient candidates for further follow-up: name RA Dec time mag z notes -------- ---------- ---------- ----- ----- ------ --------- iPTF17bo 132.510142 +46.663565 06:13 18.57 0.038 =ATLAS16ecj (GCN 20377) iPTF17bq 132.192751 +44.006807 06:11 19.11 0.054 spec-z iPTF17bs 128.827313 +44.022911 06:11 20.35 0.049 photo-z iPTF17bt 130.174781 +39.306960 06:08 20.05 0.1166 spec-z iPTF17bu 124.471393 +40.726652 06:06 20.69 0.0608 spec-z iPTF17bv 124.186115 +41.266753 06:06 19.23 0.039 spec-z iPTF17cc 125.336819 +35.420771 06:00 20.06 0.064 spec-z iPTF17ce 122.265555 +24.773640 05:55 20.19 0.350 photo-z iPTF17cf 122.967123 +25.422642 05:55 19.06 0.199 photo-z iPTF17ch 123.698029 +27.836746 05:53 20.22 0.118 photo-z iPTF17ck 115.465769 +29.353904 07:08 19.18 0.169 photo-z iPTF17cp 115.146554 +17.018280 07:05 19.90 0.072 spec-z iPTF17cs 115.613615 +13.805968 07:03 19.48 0.066 photo-z iPTF17cv 114.643374 +23.994179 07:01 20.60 0.081 photo-z iPTF17dk 120.728531 +16.489364 07:21 20.00 0.069 photo-z iPTF17dn 115.013574 +13.340217 09:11 19.08 0.037 photo-z iPTF17du 114.886641 +10.661666 07:15 20.05 0.412 photo-z iPTF17dz 126.106981 +24.997750 09:40 19.33 0.235 photo-z iPTF17eb 118.169444 +10.174427 09:20 19.78 0.573 photo-z iPTF17ec 111.440505 +17.716475 09:13 19.50 no redshift available iPTF17ee 146.552954 +60.363235 10:07 19.15 0.102 possibly variable iPTF17ef 117.10532 +20.863792 07:06 20.32 0.162 photo-z iPTF17eh 116.453873 +9.318206 07:15 19.75 0.077 photo-z iPTF17ei 114.113854 +25.736748 09:29 19.56 0.101 photo-z iPTF17ej 116.903063 +25.599466 09:29 20.40 0.543 photo-z iPTF17ep 137.758943 +62.963989 09:38 19.97 0.115 photo-z iPTF17et 126.46248 +32.611008 07:30 19.46 0.124 spec-z iPTF17ez 118.434093 +19.300562 07:14 20.19 0.538 photo-z iPTF17fa 130.091957 +38.723745 06:08 19.94 0.673 photo-z iPTF17fb 123.253486 +41.307429 06:06 20.38 0.282 photo-z iPTF17fc 123.845936 +40.118490 06:04 19.78 0.067 photo-z Some additional transients not listed above fell just outside the 90% contour localization contour, e.g. iPTF17cw 135.909904 +43.097300. Positions are stated in the ICRS. Times are in UTC. Magnitudes are based on image subtraction; they are in the Mould R filter and in the AB system, calibrated with respect to point sources in SDSS as described in Ofek et al. 2012. None of the above transients show prior history of detection in iPTF archival images. All of the above transients coincide with a galaxy that is visible in iPTF and/or SDSS images. Archival spectroscopic or photometric redshifts of the transients' likely host galaxies are given above. Of the transients, those that are most consistent with the directional distance estimate from LIGO (e.g., |[galaxy distance] - [GW mean distance]| < 1.5 * [GW distance std. dev.]) are iPTF17ce, iPTF17ck, iPTF17dz, iPTF17ef, and iPTF17ei. We encourage spectroscopic classification of these candidates. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20399 SUBJECT: LIGO/Virgo G268556: CALET Observations DATE: 17/01/08 06:15:56 GMT FROM: Takanori Sakamoto at Aoyama Gakuin U T. Sakamoto, A. Yoshida, Y. Kawakubo, M. Moriyama, Y. Yamada (AGU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA), I. Takahashi (IPMU), Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), W. Ishizaki (ICRR), M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena) and the CALET collaboration: The CALET Gamma-ray Burst Monitor (CGBM) was operating at the trigger time of G268556 (GCN Circ. 20364). No CGBM on-board trigger occurred at the time of the event. Based on the LIGO BAYESTAR localization sky map, the southern arc of the high probability area was in the field-of-view of CGBM. The summed LIGO probabilities inside the HXM and the SGM field of view are 37% and 40%. Based on the analysis of the light curve data with 0.125 sec time resolution from -60 sec to 60 sec from the trigger time, we found no significant excess around the trigger time in either the HXM (7-1000 keV) or the SGM (0.1-20 MeV) data. The CALET Calorimeter (CAL) was operating in high energy trigger mode at the trigger time of G268556. Using CAL data, we have searched for gamma-ray events above 10 GeV from -60 sec to +60 sec from the GW trigger time and found no candidates. The summed LIGO probabilities inside the CAL field of view is ~30%, which is largely overlapping with the HXM's FOV. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20400 SUBJECT: LIGO/Virgo G268556: Swift/UVOT observations of ATLAS17aeu DATE: 17/01/08 18:31:44 GMT FROM: Samantha Oates at U of Warwick S.R. Oates (Uni. of Warwick), A. A. Breeveld (MSSL-UCL), S.D. Barthelmy (NASA/GSFC), A.P. Beardmore (U. Leicester), D.N. Burrows (PSU), S. Campana (INAF-OAB), S.B. Cenko (NASA/GSFC), G. Cusumano (INAF-IASF PA), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB), V.D'Elia(ASDC), P. Evans (U Leicester), N. Gehrels (NASA/GSFC), P. Giommi (ASI), C. Gronwall (PSU), J. Kennea (PSU), H.A. Krimm (CRESST/GSFC/USRA), N.P.M. Kuin (UCL-MSSL), A.Y. Lien (GSFC/UMBC), D. Malesani (DARK/NBI), F.E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), B. Mingo (U. Leicester), J.A. Nousek (PSU), P.T. O'Brien (U. Leicester), J.P. Osborne (U. Leicester), C. Pagani (U. Leicester), K.L. Page (U.Leicester), D.M. Palmer (LANL), M. Perri (ASDC), J.L. Racusin (NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU), M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB), E. Troja (NASA/GSFC/UMCP) report on behalf of the Swift team: The Swift/UVOT performed targetted observations of the field of ATLAS transient ATLAS17aeu (Tonry et al., LVC Circ. 20382) from 00:00 UT to 01:35 UT on 2017 Jan 7 and again between 16:01 UT on 2017 Jan 7 to 01:30 on 2017 Jan 08. No optical afterglow consistent with the ATLAS position or 'source5' of the XRT follow up of G268556 (Evans et al., GCN Circ. 20390) is detected in the UVOT exposures at more than 3 sigma. We do note however a source at 2.9 sigma in the w2 filter, which in comparison to the second observation appears to have faded. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the exposures are: Filter T_start(UT) T_stop(UT) Exp(s) Mag/3sigUL v 7.007 7.009 144 > 19.1 v 7.667 7.936 1009 > 20.3 u 7.018 7.019 106 > 18.6 u 7.881 8.016 311 > 19.2 w1 7.014 7.018 290 > 19.5 w1 7.876 7.947 801 > 20.2 m2 7.009 7.014 435 > 20.0 m2 7.670 7.943 2413 > 21.2 w2 7.000 7.067 690 > 20.7 (20.76 +/- 0.37 detection at 2.9 sigma) w2 7.658 8.069 5177 > 22.0 (22.41 +/- 0.53 detection at 2.1 sigma) The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.03 in the direction of the transient (Schlegel et al. 1998). [GCN OPS NOTE(08jan17): Per author's request, PE and JK were added to the author list.] //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20401 SUBJECT: LIGO/Virgo G268556: Continued iPTF Observations and Additional Optical Transient Candidates DATE: 17/01/09 00:58:15 GMT FROM: Leo Singer at NASA/GSFC L. P. Singer (NASA/GSFC), T. Kupfer (Caltech), R. Roy (OKC), M. M. Kasliwal (Caltech), S. B. Cenko (NASA/GSFC), and T. Barlow (Caltech) report on behalf of the iPTF and GROWTH collaborations: We continued our tiled observations of LIGO/Virgo G268556 (LVC, GCN 20364) using the Palomar 48-inch Oschin telescope (P48) on the night of 2017-01-08 UTC. Including our original observations on 2017-01-07 (Kasliwal et al., GCN 20398), we have now imaged 151 fields spanning 1069 square degrees, with a 51% chance of containing the true location of the source. Applying standard iPTF vetting procedures to the images taken on 2017-01-08, we flagged the following additional optical transient candidates that had no previous history of detection or variability in iPTF. We have listed the transients in order of priority for follow-up: --------------------------------------------------------- name RA Dec time mag z notes --------------------------------------------------------- No host or quiescent source --------------------------------------------------------- iPTF17fs 162.900034 +69.833971 10:46 18.94 --------------------------------------------------------- Coincident galaxy with unknown redshift --------------------------------------------------------- iPTF17ha 230.580928 +80.725830 13:14 19.29 iPTF17gf 272.970627 +68.486958 13:32 20.03 iPTF17ft 201.323053 +78.426314 11:09 19.95 iPTF17fu 192.417627 +80.149750 11:11 18.78 iPTF17fw 156.366148 +71.757620 10:46 18.24 iPTF17gr 193.895770 +79.226903 11:11 20.21 iPTF17gv 176.227516 +82.619152 11:04 19.77 iPTF17hc 165.400920 +68.097753 10:47 19.52 --------------------------------------------------------- Known redshift inconsistent with LIGO distance estimate --------------------------------------------------------- iPTF17fe 330.745910 -03.303166 02:33 17.80 0.044 iPTF17fg 339.797294 -17.341041 02:49 16.63 0.074 iPTF17gw 178.409537 +72.864968 10:58 19.41 0.176 photo-z iPTF17gj 257.427906 +70.158947 13:29 19.74 0.258 photo-z --------------------------------------------------------- Unresolved host or quiescent source, possibly stellar --------------------------------------------------------- iPTF17he 214.716535 +79.793033 13:07 19.88 iPTF17ge 159.042893 +69.146836 10:47 19.87 iPTF17hf 195.818782 +80.173138 11:11 19.52 iPTF17hh 194.925476 +75.016124 11:08 20.34 iPTF17gu 194.101611 +78.204729 11:09 19.47 iPTF17gt 191.763759 +76.839773 11:09 19.70 iPTF17gs 199.058226 +76.521298 11:09 20.07 iPTF17hi 180.885869 +72.050360 10:58 20.30 iPTF17gn 232.045095 +74.611299 13:15 19.99 iPTF17gm 235.823172 +74.750334 13:15 19.69 iPTF17hd 213.248302 +79.332924 13:07 19.44 iPTF17gc 240.341194 +78.345723 13:17 19.54 --------------------------------------------------------- The known blazar NVSS J120651+772222 was excluded from this list. Positions are stated in the ICRS. Times are in UTC. Magnitudes are based on image subtraction; they are in the Mould R filter. Spectroscopic redshifts of coincident galaxies are obtained from NED and photometric redshifts from SDSS DR12. We encourage further follow-up of the candidates above, especially of iPTF17fs, for which no host galaxy or quiescent source was visible in archival iPTF images. Observations of this source have been requested from the GROWTH network (http://growth.caltech.edu). //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20402 SUBJECT: LIGO/Virgo G268556/GW170104: Lomonosov BDRG observations DATE: 17/01/09 07:57:14 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.V.Bogomolov, S.I.Svertilov, A.M.Amelushkin, V.O.Barinova, M.I.Panasyuk, A.V.Bogomolov, A.F.Iyudin, V.V.Kalegaev, D.Nguen, V.L. Petrov, I.V.Yashin, P.S.Kazarian, N.L.Dzhioeva, Physics Department, Skobel`tsyn Institute of Nuclear Physics, Lomonosov Moscow State University V. Lipunov, E.S. Gorbovskoy, N.Tyurina, D.Kuvshinov, M.Panchenko Lomonosov Moscow State University, Sternberg Astronomical Institute I. Park, J. Lee, S. Jeong Department of Physics, Sungkyunkwan University, Seobu-ro, Jangangu, Suwonsi, Korea At event time for G268556 the detectors BDRG-1 and BDRG-2 on-board Lomonosov were directed >60 degrees far from all regions present on LIGO probability map for G268556. BDRG-3 detector observed the southern high probability region directed to RA=25.8, Dec=-30.7. The Lomonosov satellite was located over South Africa at outer regions of SAA leading to high background. No burst-like events were observed, the 3 sigma upper limit for 1s-long GRB flux in 20-800 keV range is 2.5 cm-2*s-1. The time intervals when the region of maximal probability of GW source was in BDRG FOV on 04.01.2017 from 9h to 13h are 9:07-9:27, 9:33-9:47, 10:42-11:02, 11:07-11:24, 12:17-12:37, 12:42-12:59. No on-board GRB-triggers were generated at this time intervals. BDRG on-board triggers were generated 4 times during the time period from 10 hours before GW event to 10 hours after it (at 02:33:17, 0 4:12:19, 08:06:49 and 13:36:41).The significance of all these triggers do not exceed 9.5 sigma correspondent to the level of random events occurring ~10 times per day. The upper limit for 1s-GRB flux in 50-300 keV is 0.5 cm-2*s-1 equivalent to 1e-7 erg/cm2 for typical GRB spectra. This message can be cited. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20404 SUBJECT: LIGO/Virgo G268556: GWAC_F60B (60cm) follow-up two events of EWE001 and EWE002 DATE: 17/01/09 12:50:04 GMT FROM: Chao Wu at NAOC J.Y. Wei (NAOC), L.P. Xin (NAOC), X.M. Meng (NAOC), X.H. Han (NAOC), N.Leroy (LAL), S. Antier (LAL), C. WU (NAOC), L. Huang (NAOC), Y. Xu (NAOC), H.B. Cai (NAOC), J. Wang (NAOC), X.M. Lu (NAOC), Y.L. Qiu (NAOC), J.S. Deng (NAOC), L. Cao (NAOC), S. Wang (NAOC), L. Jia (NAOC), S.C. Zou(NAOC), S.F. Liu(NAOC), Q.C. Feng(NAOC), H.L. Li(NAOC), D.W. Xu (NAOC), Y.J. Xiao (NAOC), W.L. Dong(NAOC), Y.T. Zheng(NAOC), E.W.Liang (GXU), X.G. Wang(GXU), Y.G. Yang (HBNU), B. Cordier (CEA), S.N. Zhang (NAOC), S. Basa (LAM), B.B. Wu (IHEP), Jean-Luc Atteia (IRAP), D. Götz (CEA), C. Lachaud (APC) on behalf of the SVOM Gravitational Astronomy group report: We took images on the location of two events of EWE001 and EWE002 (Liu et al LVC Circ. 20382) with our GWAC_F60B (60cm) telescope, which is dedicated to identify transient candidates found by GWAC (a part of ground instrument of SVOM mission) at Xinglong Observatory, China. Observation were obtained in R band for 15 X 900s expoures during 16:49:29 and 22:02:03 (UTC) on Juanary 8, 2017. The two events(objects) are corresponding to known objects in USNO-B1.0 catalog. ----------------------------------------------------------------------- EWE001: mag_R = 16.98 mag_R2(in USNO) = 15.35 EWE002: mag_R=16.77 mag_R2(in USNO) = 16.57 ------------------------------------------------------------------------ The photometric uncertainty is ~ 5%. The comparison star is object with mag_R2 =16.17 (09:13:19.611 61:05:44.13 J2000). //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20406 SUBJECT: LIGO/Virgo G268556: IPN Triangulation of GRB 170105A (association with ATLAS17aeu) DATE: 17/01/09 16:38:27 GMT FROM: Dmitry Svinkin at Ioffe Institute D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Tsvetkova, A. Kozlova, and T. Cline on behalf of the Konus-Wind team, K. Hurley, on behalf of the IPN, and A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, report: The long-duration, soft-spectrum GRB 170105A was detected by POLAR (Marcinkowski et al., GCN Circ. 20387), AstroSat (CZTI; Sharma et al., GCN Circ. 20389), Konus-Wind, and INTEGRAL (SPI-ACS) at about 22447 s UT (06:14:07). We have triangulated this GRB to a Konus-INTEGRAL annulus centered at RA(2000)=129.749 deg (08h 38m 60s) Dec(2000)=+27.904 deg (+27d 54' 14"), whose radius is 34.255(-14.832,+1.812) deg (3 sigma). This localization may be improved. The distance between the annulus center line and the ATLAS17aeu optical transient reported by Tonry et al. (LVC Circ. 20382) is 0.57 degrees, strengthening the association of the transient with the GRB initially suggested by Kasliwal et al. (LVC Circ. 20393). A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB170105_T22450/IPN/. As observed by Konus-Wind, the burst had a fluence of 2.56(-0.13,+0.18)x10^-6 erg/cm2, and a 64-ms peak energy flux, measured from T0-0.204 s, of 2.47(-0.30,+0.58)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB170105_T22450/. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20407 SUBJECT: LIGO/Virgo G268556: Gemini spectrum and Pan-STARRS observations of ATLAS17aeu DATE: 17/01/09 16:52:22 GMT FROM: S. J. Smartt at Queens U Belfast K. C. Chambers (IfA), S. Smartt (QUB), J. Tonry, L. Denneau, A. Heinze, B. Stalder, H. Weiland (IfA), C. W. Stubbs (Harvard), K. W. Smith (QUB), T.-W. Chen (MPE), T. Kruehler (MPE), D. R. Young (QUB), A. Rest (STScI), M. Coughlin (Harvard), M. E. Huber (IfA), D. E. Wright (QUB), H. Flewelling, E. A. Magnier, A. S. B. Schultz, C. Waters, R. J. Wainscoat (IfA) Further to our discovery of ATLAS17aeu (Tonry et al. GCN 20382), we took a spectrum with Gemini-North + GMOS (R400 grating, 4491-8778 Angs) on MJD = 57761.595. We also took an r-band image on the same night. The spectrum has a blue featureless continuum, with a signal-to-noise in the continuum S/N~10 at 7000Angs. There are no clear emission or absorption lines visible that can anchor a redshift estimate. The spectrum is not unlike some GRB afterglows as shown in the compilation of Fynbo et al. 2009, ApJS 185, 526 e.g. GRB060512, at z~2.1, GRB061110A (z=0.7578), GRB070129 (no z estimate, but below z<3.4) We report three more photometric points, two from Pan-STARRS1 and the other from Gemini+GMOS. MJD Mag Telescope 57758.38159 18.18 0.04 i Pan-STARRS1 57759.46468 20.90 0.12 i Pan-STARRS1 57761.51968 22.77 0.17 r Gemini+GMOS These data further support the hypothesis of Kasliwal et al. GCN 20393 that this is most likely the afterglow of GRB170105A, supported by the x-ray and radio detections of Evans et al. GCN 20390 and Corsi et al. GCN 20396. Using the POLAR detection time, a temporal index of F_nu \propto t**(-1.4) would be consistent with the photometry reported to date, typical of GRB afterglows. We note there are several other faint galaxies closer to ATLAS17aeu than the brighter galaxy at z = 0.199 highlighted in Tonry et al. (GCN 20382). They have SDSS photometric redshifts of z ~ 0.35 - 0.38, but are marginal detections in more than one band and therefore the photometric redshifts are uncertain. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20408 SUBJECT: LIGO/Virgo G268556/GW170104: TNG spectroscopic observations of iPTF17ck and iPTF17dz DATE: 17/01/09 17:44:47 GMT FROM: Paolo D'Avanzo at INAF-OAB P. D'Avanzo (INAF-OAB), L. Tomasella, E. Cappellaro (INAF-OAPD), S. Piranomonte (INAF-OAR), A. Melandri (INAF-OAB), V. D'Elia (INAF-ASDC), G. Greco (Urbino University/INFN Firenze), G. Stratta (Urbino University/INFN Firenze), S. Ascenzi (INAF-OAR), M.T. Botticella (INAF-OAC), E. Palazzi (INAF-IAFS Bo), A. Rossi (INAF-IASF Bo), S. Covino (INAF-OAB), L.Amati (INAF-IASF Bo), L. A. Antonelli, (INAF-OAR), M. Branchesi (Urbino University/INFN Firenze), S. Campana (INAF-OAB), F. Getman (INAF-OAC), A. Grado (INAF-OAC), L. Limatola (INAF-OAC), M. Lisi (INAF-OAR), L. Nicastro (INAF-IASF Bo), E. Pian (SNS-Pisa), L. Pulone (INAF-OAR), G. Tagliaferri (INAF-OAB), V. Testa (INAF-OAR), S. Yang (INAF-OAPD), E. Brocato (INAF-OAR), L. Di Fabrizio, G. Mainella (INAF/TNG) on behalf of GRavitational Wave Inaf TeAm report: We observed the transients iPTF17ck and iPTF17dz (Kasliwal et al., LVC GCN 20398) with the TNG 3.6m telescope located in Canary Islands equipped with the DOLORES camera in spectroscopic mode. The observations were carried out between 2017-01-09.1044 UT and 2017-01-09.1797 UT. The iPTF17ck spectrum is consistent with a Seyfert galaxy. We detect prominent emission features consistent with [OII], Hdelta, Hgamma, Hbeta, [OIII], Halpha at a common redshift z~0.122 (broadly consistent with the photometric redshift of this galaxy reported in SDSS-DR13: z=0.169 +/- 0.034). We cannot identify any contribution from the optical transient in the spectrum, nor in the acquisition image. The iPTF17dz spectrum shows that this transient is a normal SN of type Ia about 1 week before maximum at a redshift z~0.092 (that is smaller than the photometric redshift of this galaxy reported in SDSS-DR13: z=0.235 +/- 0.085). The classification was performed using the GELATO (Harutyunyan et al. 2008, A&A, 488, 383) and SNID (Blondin and Tonry 2007, ApJ, 666, 1024) tools. [GCN OPS NOTE(10jan17): Per author's request, all the SN name references were changed from '16' to '17'.] //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20409 SUBJECT: LIGO/Virgo G268556/GW170104: 10.4m GTC spectroscopic observations of iPTF17fs DATE: 17/01/09 18:49:59 GMT FROM: Alberto J. Castro-Tirado at IAA-CSIC A. J. Castro-Tirado, B.-B. Zhang, J. C. Tello, Y. Hu (IAA-CSIC, Granada), M. D. Caballero-Garcia (ASU-CAS), V. V. Sokolov, V. V. Vlasjuk, A. F. Valeev (SAO-RAS), E. Pian (SNS-Pisa), S. Jeong (SKKU), S. R. Oates (Warwick) and P. Pessev (GRANTECAN), on behalf of a larger collaboration, report: We observed the transient iPTF17fs (Singer et al., LVC GCN 20401) with the 10.4m GTC telescope located at La Palma (Canary Islands, Spain) equipped with the OSIRIS spectrograph. The observations were carried out starting on Jan 9, 5:30 UT. The iPTF16fs spectra covering the range 3700-10000 A shows that this transient is a type Ia SN about 1 week before maximum at a redshift z~0.068. We acknowledge excellent support from the GTC staff. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20410 SUBJECT: LIGO/Virgo G268556: Pan-STARRS1 observations and summary of transient sources DATE: 17/01/09 21:05:14 GMT FROM: S. J. Smartt at Queens U Belfast S. J. Smartt, (QUB), K. W. Smith (QUB), M. E. Huber (IfA), K. C. Chambers (IfA), D. R. Young, D. E. Wright (QUB), M. Coughlin (Harvard), L. Denneau, H. Flewelling, A. Heinze, E. A. Magnier (IfA), A. Rest (STScI), B. Stalder (IfA), A. S. B. Schultz, C. W. Stubbs (Harvard) J. Tonry, C. Waters, R. J. Wainscoat, H. Weiland (IfA) Further to Chambers et al. GCN 20383, we report that we covered 632 square degrees on the first night (beginning 57758.3) . We estimate this corresponds to a probability of containing the source of 33%. We have since reduced this area to the higher probability central region, recovering 357 sq degrees and a containment probability of 26% (based on the LALInference map, GCN 20385). Images were taken in the Pan-STARRS i-band in a series of overlapping 45s exposures, with typically 4-8 images at each position. These were combined into stacks and subtracted from the Pan-STARRS1 3Pi reference image (Chambers et al. arXiv:1612.05560, and available at http://panstarrs.stsci.edu). Using techniques discussed in Smartt et al. (2016, MNRAS, 462, 4094), we have located and vetted transients with quality filters and a machine learning algorithm on the images. We recover 6 iPTF objects and 15 old transients known before the GW alert (given at the end for completeness). ATLAS17aeu was recovered as discussed in Chambers et al. (GCN 20407) In the following table, we give our 55 targets, sorted by magnitude. The lightcurve trend is given (LC trend), indicating the change in magnitude between earliest and latest MJD of detection. To select these targets we required a minimum of 2 detections over 2 separate nights. Our area is completely within the SDSS DR12 footprint, and we give the redshifts (p for photometric and s for spectroscopic) of the host galaxies. Objects with no obvious host are labelled "hostless". Some targets are coincident with faint sources in SDSS for which star/galaxy separation and photo-z estimates are not reliable and we note these. We have removed obvious AGN and candidate AGN (low level variability associated with galaxy cores), as well as stellar variables. In the comments we note iPTF coincidences (Singer et al. GCN 20401; Kasliwal et al. GCN 20364). A small number of candidates have a low real-bogus (RB) machine learning factor and should be treated with caution. All have been scanned by human reviewers. The photometric redshifts from SDSS should not be used as a robust filtering for distance (see discussion in Smartt et al. 2016), but we provide them as a guide. We are targeting the objects with changing lightcurves with Gemini+GMOS. Name RA DEC LC trend Earliest mjd mag Latest mjd z Comment PS17df 08:50:02.42 +46:39:48.8 fading 00.09 57758.43699 18.39 57759.4911 0.038 s iPTF17bo PS17fg 08:48:46.25 +44:00:24.6 fading 00.15 57758.42737 18.89 57761.4882 0.060 s iPTF17bq PS17fr 08:11:52.10 +25:25:21.4 rising 00.57 57758.43263 19.19 57761.4619 0.199 p iPTF17cf PS17fe 09:00:21.22 +63:50:49.8 fading 00.09 57758.39189 19.60 57759.4726 0.245 p PS17du 09:14:30.59 +54:28:34.4 fading 00.04 57758.42705 19.75 57759.4660 0.045 s 0.6" from core PS17dp 09:00:51.09 +45:26:44.3 rising 00.06 57758.39978 19.97 57759.5043 0.051 s PS17gl 08:34:50.85 +61:13:02.2 rising 00.07 57758.39093 20.04 57759.4635 0.038 s PS17ft 08:16:52.72 +26:27:25.3 fading 00.05 57758.44356 20.05 57761.4790 0.042 s PS17fs 08:14:47.53 +27:50:12.2 fading 00.11 57758.45845 20.09 57761.4891 0.118 p iPTF17ch PS17bz 08:04:49.22 +29:19:48.8 fading 00.08 57758.40250 20.23 57761.4809 0.047 s PS17fb 08:49:18.13 +44:38:31.1 rising 00.01 57758.41320 20.30 57759.4831 0.151 p PS17fh 07:55:14.13 +26:25:11.5 fading 00.14 57758.39608 20.32 57761.4492 0.119 p PS17fw 08:19:05.64 +23:20:42.8 fading 00.04 57758.40905 20.35 57761.4478 0.034 p PS17gb 08:21:17.00 +51:10:17.1 rising 00.13 57758.38839 20.36 57759.4635 0.197 p PS17fa 08:47:22.51 +51:08:17.4 fading 00.02 57758.44371 20.41 57759.4865 0.497 p PS17en 08:40:22.10 +38:43:25.0 fading 00.07 57758.44053 20.41 57761.4923 0.673 p iPTF17fa PS17dy 08:13:00.78 +41:18:26.9 rising 00.00 57758.42812 20.43 57761.4760 0.282 p iPTF17fb PS17er 08:41:57.26 +40:55:07.7 rising 00.36 57758.45114 20.44 57761.4854 0.296 p PS17fj 07:59:30.67 +28:27:03.8 fading 00.37 57758.41011 20.46 57761.4771 hostless PS17fl 08:02:09.73 +28:49:44.7 rising 00.32 57758.42406 20.47 57761.4876 0.080 p PS17dw 07:49:25.36 +20:28:00.6 fading 00.05 57758.38695 20.48 57759.4846 0.171 p PS17fv 08:18:15.52 +43:45:03.4 fading 00.06 57758.45210 20.56 57761.5017 0.188 s PS17gf 08:24:43.98 +35:29:45.8 rising 00.14 57758.46042 20.62 57761.4786 0.362 p PS17gr 08:20:14.14 +27:13:44.2 fading 00.20 57759.47191 20.64 57761.4792 hostless PS17gk 08:33:00.93 +38:51:04.7 fading 00.18 57758.43419 20.68 57761.4721 0.163 p PS17fy 08:19:47.91 +42:39:45.9 fading 00.09 57758.41450 20.73 57761.4678 0.166 p PS17gv 08:54:41.22 +57:10:45.9 rising 00.08 57758.46079 20.82 57759.5027 0.076 p PS17gm 08:35:15.00 +48:27:06.2 fading 00.04 57758.44909 20.83 57759.4940 0.159 p PS17fx 08:19:36.86 +48:06:38.9 fading 00.04 57758.42693 20.84 57759.4803 hostless PS17dk 08:55:48.76 +46:55:04.8 rising 00.10 57758.42465 20.85 57759.4746 0.567 p PS17fp 08:06:52.00 +34:18:04.4 fading 00.22 57758.43602 20.85 57761.4726 0.193 p PS17fm 08:02:26.56 +26:20:07.5 fading 00.05 57758.42467 20.85 57761.4661 hostless low RB factor PS17dj 08:54:13.87 +48:19:42.7 rising 00.05 57758.44299 20.86 57759.4844 0.382 p PS17ea 08:30:11.01 +32:57:35.8 rising 00.32 57758.43602 20.88 57761.5046 0.110 p PS17fn 08:05:51.40 +28:42:51.9 rising 00.59 57758.44882 20.88 57761.4973 0.072 p PS17ga 08:20:47.13 +30:24:47.9 fading 00.03 57758.45271 20.90 57761.4895 r=22.35, faint source PS17fo 08:06:49.10 +28:16:05.9 rising 00.27 57758.44882 20.92 57761.4804 0.179 p PS17gg 08:30:06.42 +48:28:34.4 fading 00.17 57758.43638 20.93 57759.4841 0.144 p low RB factor PS17cj 08:10:23.04 +23:59:52.6 fading 00.10 57758.39319 20.94 57761.4614 r=22.9, faint source PS17dh 08:50:43.44 +56:42:44.0 rising 00.06 57758.43403 20.95 57759.4998 hostless PS17fu 08:17:35.59 +47:05:06.3 rising 00.23 57758.41830 20.95 57761.4746 0.040 s PS17ei 08:37:00.85 +38:42:47.2 fading 00.01 57758.44228 20.98 57761.4775 hostless PS17fz 08:19:57.24 +45:12:59.8 fading 00.17 57758.44267 21.14 57761.4625 0.175 p PS17gj 08:32:56.15 +41:12:22.3 rising 00.08 57758.44494 21.17 57761.4882 0.276 p PS17ec 08:35:47.59 +46:25:09.4 rising 00.11 57758.46003 21.24 57759.4855 0.403 p PS17dx 08:05:30.92 +36:26:24.8 fading 00.08 57758.40284 21.33 57761.4500 hostless PS17dz 08:24:48.80 +30:53:37.3 fading 00.10 57759.48293 21.35 57761.4982 0.308 p PS17el 08:39:41.07 +39:24:30.2 fading 00.03 57758.45160 21.37 57761.4788 hostless PS17gt 08:11:47.50 +37:44:39.4 rising 00.12 57759.47465 21.42 57761.4739 0.348 s PS17cw 08:38:37.02 +42:57:05.4 fading 00.12 57758.44623 21.46 57761.4923 0.35 p PS17gw 08:48:29.00 +43:24:48.4 rising 00.05 57759.47696 21.54 57761.4915 hostless PS17gd 08:23:08.94 +43:55:57.1 rising 00.06 57758.44611 21.56 57761.4711 r=22.4, faint source PS17b 08:23:44.47 +36:53:39.2 rising 00.15 57759.49179 21.62 57761.4837 0.224 p PS17gs 08:11:41.68 +38:28:22.4 fading 00.06 57759.47749 21.63 57761.4760 r=22.45, faint source PS17gu 08:11:48.78 +37:18:50.3 fading 00.19 57759.46588 21.99 57761.4715 r=22,faint source This object was only detected on one night (we have no coverage of the specific area afterwards), but has a high RB factor and is coincident with a starforming galaxy. Hence it appears real, but we caution that we do not have multiple night detections. PS17co 08:13:46.29 +18:59:02.4 rising 00.02 57758.40522 18.30 57758.4070 0.124 s The following transients were all recovered in our imaging, but were discovered and reported well before G268556 was discovered. AT2017M 08:23:09.79 +25:53:22.9 aka MLS150212-082310+255323 AT2017N 08:25:42.74 +39:19:00.6 PS1-14amh 07:55:40.63 +26:46:18.0 SN2016hrv 08:33:21.92 +52:31:50.4 ASASSN-16el 08:56:39.07 +52:06:08.0 AT2016iyx 08:43:24.73 +37:32:45.8 AT2016jax 08:32:53.76 +42:08:01.6 SN2016gil 08:10:13.72 +33:57:25.6 SN2016ins 08:07:27.35 +25:07:47.3 AT2016jau 08:00:40.94 +28:19:31.8 SN2016hqh 07:57:05.78 +23:08:55.2 AT2016jci 07:56:05.83 +28:22:35.3 AT2016jay 09:21:43.35 +61:31:59.6 AT2016hys 08:14:42.11 +38:24:08.5 //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20411 SUBJECT: LIGO/Virgo G268556: Liverpool Telescope Spectroscopy of iPTF candidates DATE: 17/01/09 21:50:14 GMT FROM: Iain Steele at Liverpool/JMU Liverpool Telescope Spectroscopy of iPTF-17bq and iPTF-17ee I.A. Steele, A.S. Piascik, M.J.Darnley, C.M. Copperwheat (LJMU), M. M. Kasliwal (Caltech) and D. Perley (Dark Cosmology Centre, Copenhagen) report on behalf of a lager collaboration. We report spectroscopy of the iPTF counterparts iPTF-17bq and iPTF-17ee. The data were obtained with the SPRAT spectrograph of the Liverpool Telescope, La Palma, on the night of 2017 January 08 with a resolution R=350 and a wavelength range of 400-800nm. In both cases the transient could not be clearly distinguished from the host galaxy in our spectra, which were obtained in poor (~2 arcsec) seeing. iPTF17-bq shows a galaxy spectrum with redshift (SNID) z=0.059 and AGN-like emission lines. iPTF17-ee shows a galaxy spectrum with redshift (SNID) z=0.085. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20413 SUBJECT: LIGO/Virgo G268556: ATLAS17aeu position is consistent with GRB170105A DATE: 17/01/10 06:15:41 GMT FROM: Varun Bhalerao at IUCAA Varun Bhalerao (IUCAA), Sujay Mate (IUCAA), Dipankar Bhattacharya (IUCAA), Sukanta Bose (IUCAA), Gulab Chand Dewangan (IUCAA), Ranjeev Misra (IUCAA), Sanjit Mitra (IUCAA), A R Rao (TIFR), Tarun Souradeep (IUCAA), Santosh Vadawale (PRL), on behalf of the Astrosat CZTI team report: Bhalerao et al. (GCN Circ. 20412) have used AstroSat CZTI to infer that GRB170105A is a long GRB, and have localised it to a ~550 square degree region (1-sigma). This region includes 3.9% probability of containing the LIGO trigger G268556, based on the revised LALInference sky map (Greco et al, 20385). The overlap with the IPN triangulation (Svikin et al., GCN Circ. 20406) is about 50 square degrees. The position of ATLAS17aeu (Tonry et al., GCN Circ. 20382) is marginally outside the AstroSat CZTI error region, consistent at better than 1.1 sigma. This further indicates that ATLAS17aeu is the afterglow of GRB170105A (Kasliwal et al., GCN Circ. 20393). //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20415 SUBJECT: LIGO/Virgo G268556: Swift-XRT confirms that ATLAS17aeu is fading in X-rays DATE: 17/01/10 09:45:26 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester), J.A. Kennea (PSU), S.D. Barthelmy (NASA/GSFC), A.P. Beardmore (U. Leicester), A.A. Breeveld (UCL-MSSL), D.N. Burrows (PSU), S. Campana (INAF-OAB), S.B. Cenko (NASA/GSFC), G. Cusumano (INAF-IASF PA), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB), V.D'Elia (ASDC), N. Gehrels (NASA/GSFC), P. Giommi (ASI), C. Gronwall (PSU), H.A. Krimm (CRESST/GSFC/USRA), N.P.M. Kuin (UCL-MSSL), A.Y. Lien (GSFC/UMBC), D. Malesani (DARK/NBI), F.E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), B. Mingo (U. Leicester), J.A. Nousek (PSU), S.R. Oates (U. Warwick), P.T. O'Brien (U. Leicester), J.P. Osborne (U. Leicester), C. Pagani (U. Leicester), K.L. Page (U.Leicester), D.M. Palmer (LANL), M. Perri (ASDC), J.L. Racusin (NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU), M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB), E. Troja (NASA/GSFC/UMCP) report on behalf of the Swift team: Swift has continued to observed ATLAS17aeu (Tonry et al., LVC Circ. 20382), gathering a total of 21.3 ks of data, from T0+222 ks to T0+470 ks (where T0 is the GW trigger time). The X-ray counterpart (Evans et al., LVC Circ. 20390) is now confirmed to be fading. Assuming the trigger time from the GW event (LVC Circ. 20364) the light curve is decaying with a power-law index of 2.2 (+1.1, -1.2). If instead we take T0 from GRB 170105A (Marcinkowski et al., GCN Circ. 20387), the decay index is 1.7 (+1.1, -0.9). At the mid-point of the latest observation, GW_T0+453 ks (=GRB_T0+381 ks) the 0.3-10 keV XRT count-rate was 0.0017 (+/- 0.0006) ct/sec. A spectrum compiled from the data can be fitted with an absorbed power-law, with NH consistent with the Galactic value of 4.6e20 cm^-2 (Willingale et al. 2013) and photon index Gamma=1.60 (+0.4, -0.3). Using this spectrum the count-rate above corresponds to an observed (unabsorbed) 0.3-10 keV flux of (6.7+/-2.4)e-14 ( [7.2+/-2.6]e-14) erg cm^-2 s^-1. The spectral and temporal indices are consistent with the values typically seen for X-ray GRB afterglows (e.g. the Swift-XRT GRB catalogue: http://www.swift.ac.uk/xrt_live_cat/; Evans et al. 2009). This circular is an official product of the Swift GW follow up team. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20416 SUBJECT: LIGO/Virgo G268556/GW170104: TNG observations of ATLAS17aeu DATE: 17/01/10 11:27:39 GMT FROM: Andrea Melandri at INAF-OAB A. Melandri (INAF-OAB), S. Piranomonte (INAF-OAR), P. D'Avanzo (INAF-OAB), G. Greco (Urbino University/INFN Firenze), G. Stratta (Urbino University/INFN Firenze), S. Ascenzi (INAF-OAR), M.T. Botticella (INAF-OAC), E. Palazzi (INAF-IASF Bo), A. Rossi (INAF-IASF Bo), E. Cappellaro (INAF-OAPD), S. Covino (INAF-OAB), V. D'Elia (INAF-ASDC), L. Amati (INAF-IASF Bo), L. A. Antonelli, (INAF-OAR), M. Branchesi (Urbino University/INFN Firenze), S. Campana (INAF-OAB), F. Getman (INAF-OAC), A. Grado (INAF-OAC), L. Limatola (INAF-OAC), M. Lisi (INAF-OAR), L. Nicastro (INAF-IASF Bo), E. Pian (SNS-Pisa), L. Pulone (INAF-OAR), G. Tagliaferri (INAF-OAB), V. Testa (INAF-OAR), L. Tomasella (INAF-OAPD), S. Yang (INAF-OAPD), L. Di Fabrizio, G. Mainella (INAF/TNG), E. Brocato (INAF-OAR) on behalf of GRavitational Wave Inaf TeAm report: We observed the position of the transient ATLAS17aeu (Tonry et al., LVC Circ. 20382) with the TNG 3.6m telescope located in Canary Islands equipped with the DOLORES camera in imaging mode. Observations consisted in 8x120s exposures in the I-band. The transient is clearly detected with a magnitude I = 22.5 +/- 0.3 (Vega) at a mid time of 02:14:12 UT on 2017 Jan 8. [GCN OPS NOTE(10jan17): Per author's request, the time in the last sentence was changed from 14:12" to "02:14:12".] //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20417 SUBJECT: LIGO/Virgo G268556: NOWT of EWE, Xinglong 0.6/0.9m, Xuyi 1m optical upper limits of ATLAS17aeu and a reminder of GCN 20394 DATE: 17/01/10 15:22:53 GMT FROM: Jinzhong Liu at Xinjiang Astronomical Observatory D. Xu (NAOC/CAS), J.Z. Liu, H.B. Niu, Y. Zhang, X. Zhang, G.X. Pu, S.G. Ma, T.Z. Yang, F.F. Song (XAO), X. Zhou, T.M. Zhang (NAOC/CAS), H.B. Zhao, B. Li, G.T. Zhaori (PMO), J.M. Bai, J.R. Mao (YNAO) report on behalf of a Chinese Gravitational Wave collaboration: We have performed tiled observations of LIGO/Virgo G268556 (LVC, GCN 20364) using the Nanshan One-meter Wide field Telescope (NOWT), Xinjiang, China, the 0.6/0.9-m Schmidt telescope at Xinglong, Hebei, China, and the 1-m telescope at Xuyi, Jiangsu, China. The Nanshan 1-m has a FOV of 1.3x1.3 deg^2, and covered the position of ATLAS17aeu (Tonry et al. GCN 20382), the potential optical afterglow of GRB 170105A (e.g., Marcinkowski et al., GCN 20387; Sharma et al., GCN 20389; Kasliwal, et al., GCN 20393), in a single night. We obtained an upper limit of m(V)>20.0 mag (3 sigma) at 14:55 UT on 2017-01-07. The 0.6/0.9-m Schmidt telescope has a FOV of 1.5x1.5 deg^2, and covered the position of ATLAS17aeu also in a single night. We obtained an upper limit of m(White)>18.8 mag (5 sigma) at 18:26 UT on 2017-01-08. The Xuyi 1-m has a FOV of 3.0x3.0 deg^2, and covered the position of ATLAS17aeu in a single night. We obtained an upper limit of m(r)>14 mag (3 sigma) at 14:32 UT on 2017-01-09. In addition, we note that the two sources, dubbed EWE001 and EWE002, in GCN 20394, are obviously known sources in several surveys such as DSS II and SDSS. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20419 SUBJECT: LIGO/Virgo G268556: Spectroscopic observations of ATLAS17aeu and iPTF17cw DATE: 17/01/10 16:58:02 GMT FROM: Mansi M. Kasliwal at Caltech T. Kupfer (Caltech), R. Quimby (SDSU), S. M. Adams (Caltech), H. Vedantham (Caltech), M. M. Kasliwal (Caltech) report on behalf of the GROWTH (Global Relay of Observatories Watching Transients Happen) and iPTF (intermediate Palomar Transient Factory) collaborations We report the spectroscopic follow-up observations on ATLAS17aeu (Tonry et al. LVC GCN #20382) and iPTF17cw (Kasliwal et al. LVC GCN #20398) using the Double Beam spectrograph (DBSP) on the Palomar 200-inch telescope. The position of both targets are within the probability contour of LIGO/Virgo G268556 (LVC, GCN #20364). All observations were obtained on 2017 Jan 7 UT under poor weather conditions with a partly cloudy sky. Classifications were performed using Superfit (Howell et al. 2005, ApJ, 634, 1190). ATLAS17aeu was observed on 2017-01-07.5 UT with a total exposure time of 60 min resulting in a signal to noise ratio ~1.5 in the continuum. No obvious emission or absorption lines are detected in the spectrum. To search for features from a Galactic source at z=0, we set a 3-sigma flux limit around 6563 Angstrom of 3.3e-17 ergs/s/cm^2/A. This result is consistent with Chambers et al. (LVC GCN #20407) who reported a featureless spectrum of ATLAS17aeu obtained with Gemini. iPTF17cw was observed on 2017-01-07.55 with a total exposure time of 20 min which results in a signal to noise ratio ~11 in the continuum. The spectrum shows a blue continuum peaking around 3850 Angstroem (rest frame) with weak, broad features. We found a good match of the spectrum with the SNIc-BL SN1998bw pre-maximum at z=0.093. The redshift is consistent with the photoz=0.101±0.0279 derived by SDSS for the host Galaxy. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20420 SUBJECT: LIGO/Virgo G268556: Liverpool Telescope Spectroscopy of iPTF17bv and iPTF17ck DATE: 17/01/10 21:45:03 GMT FROM: Iain Steele at Liverpool/JMU I.A. Steele, A.S. Piascik, M.J.Darnley, C.M. Copperwheat (LJMU), M. M. Kasliwal (Caltech) and D.A. Perley (Dark Cosmology Centre, Copenhagen) on behalf of a lager collaboration. We report spectroscopy of the iPTF counterparts iPTF17bv and iPTF17ck. The data were obtained with the SPRAT spectrograph of the Liverpool Telescope, La Palma, on the night of 2017 January 09 with a resolution R=350 and a wavelength range of 400-800nm. Our spectrum of iPTF17bv is noisy, but shows a possible Supernova Ic (post maximum) spectrum with z=0.039. The nearest host galaxy is 2MASX J08164468+4115597 with z=0.0385. iPTF17ck shows a probable AGN/Galaxy spectrum with redshift z=0.121. The nearest host is SDSS J074151.78+292114.1 (no redshift quoted). //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20421 SUBJECT: LIGO/Virgo G268556: Lijiang Observatory GMG Telescope Upper Limit on ATLAS17aeu DATE: 17/01/10 23:03:21 GMT FROM: Mansi M. Kasliwal at Caltech A.K.H. Kong (NTHU/Oxford), J. Mao, X. Hou, J. Wang, and J.-M. Bai (YNAO) We observed the field of the optical transient ATLAS17aeu (Tonry et al., LVC GCN 20382; Kasliwal et al., GCN 20398) that is within the error region of LIGO/Virgo G268556 (LVC, GCN 20364) with the 2.4-m GMG telescope at the Lijiang Observatory in Yunnan, China. We obtained an R-band image with the Yunnan Faint Object Spectrograph and Camera (YFOSC) on 2017-01-07 14:55:35 UT. ATLAS17aeu was not detected with a 3-sigma limit of about R~23 mag. ATLAS17aeu was detected with i=21.9 mag on 2017-01-07 08:05:33 UT (Kasliwal et al., GCN 20398) and was proposed to be the afterglow of GRB 170105A. Our observation indicates that the source is fainter than the suggested power-law decay. However, due to the use of different filters in ATLAS, Palomar, and Lijiang, the lightcurve should be treated with caution. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20422 SUBJECT: LIGO/Virgo G268556: Swift/BAT data search DATE: 17/01/11 00:10:36 GMT FROM: Takanori Sakamoto at Aoyama Gakuin U A.Y. Lien (GSFC/UMBC), S.D. Barthelmy (NASA/GSFC), D.M. Palmer (LANL), T. Sakamoto (AGU), A. A. Breeveld (MSSL-UCL), A.P. Beardmore (U. Leicester), D.N. Burrows (PSU), S. Campana (INAF-OAB), S.B. Cenko (NASA/GSFC), G. Cusumano (INAF-IASF PA), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB), V.D'Elia(ASDC), P.A. Evans (U. Leicester), N. Gehrels (NASA/GSFC), P. Giommi (ASI), C. Gronwall (PSU), J. A. Kennea (PSU), H.A. Krimm (CRESST/GSFC/USRA), N.P.M. Kuin (UCL-MSSL), D. Malesani (DARK/NBI), F.E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), B. Mingo (U. Leicester), J.A. Nousek (PSU), S.R. Oates (Uni. of Warwick), P.T. O'Brien (U. Leicester), J.P. Osborne (U. Leicester), C. Pagani (U. Leicester), K.L. Page (U.Leicester), M. Perri (ASDC), J.L. Racusin (NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU), M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB), E. Troja (NASA/GSFC/UMCP) report on behalf of the Swift team: We report the search results in the BAT data within T0 +/- 100 s of the LIGO event G268556 (Shawhan et al. GCN Circ. 20364) , where T0 is the LIGO trigger time (2017-01-04T10:11:58:599 UTC). The BAT pointing position at T0 is RA = 166.157 deg, DEC = 38.204 deg, ROLL = 81.247 deg. The BAT Field of View (>0.1 partial coding) covers 48% of the integrated LIGO localization probability. There are no BAT event data in this time range (usually event data are only collected for ~ 1000 s around the BAT trigger time). Also, no significant detections (signal-to-noise ratio > 4 sigma) are found in the BAT raw light curves with time bins of 64 ms, 1 s, and 1.6 s, respectively. Assuming an on-axis (100% coded) short GRB with a typical spectrum in the BAT energy range (i.e., a simple power-law model with a power-law index of -1.32; Lien & Sakamoto et al. 2016), the 4-sigma upper limit in the 1-s binned light curve corresponds to a flux upper limit (15-350 keV) of ~ 6.0 x 10^-8 erg/s/cm^2. BAT retains decreased, but significant, sensitivity to rate increases for gamma-ray events outside of its FOV. About 19% of the integrated LIGO localization probability was outside of the BAT FOV but above the Earth's limb from Swift's location, and the corresponding flux upper limits for this region are within roughly an order of magnitude of those within the FOV. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20425 SUBJECT: LIGO/Virgo G268556: AMI 15 GHz detection of ATLAS17aeu DATE: 17/01/11 12:58:07 GMT FROM: Kunal Mooley at U of Oxford K. P. Mooley, R. P. Fender (Oxford), A. Horesh (HUJI) report on behalf of a larger collaboration We observed the optical transient ATLAS17aeu (Tonry et al., LVC GCN 20382) located in the error region of LIGO/Virgo G268556 (LVC GCN 20364) with the AMI Large Array on 2017 Jan 07.04 UT. At 15.5 GHz, the flux density of the source is 336+/-20 uJy. We are currently monitoring this source. We thank the AMI staff for scheduling this observation. Since this source is likely the afterglow of GRB 170105A (e.g. Kasliwal et al., LVC GCN 20393; Chambers et al., LVC GCN 20407), we will be updating the AMI-GRB database (http://4pisky.org/ami-grb/) with the measurements. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20426 SUBJECT: LIGO/Virgo G268556/GW170104: Campo Imperatore Observatory observations DATE: 17/01/11 14:51:16 GMT FROM: Paolo D'Avanzo at INAF-OAB A. Giunta, A. Di Paola, M. Centrone, N. Napoleone, P. Tedesco (INAF-OAR), S. Covino, P. D'Avanzo, A. Melandri (INAF-OAB), L. Amati (INAF-IASF Bo), L. A. Antonelli, (INAF-OAR), S. Ascenzi (INAF-OAR), M.T. Botticella (INAF-OAC), M. Branchesi (Urbino University/INFN Firenze), S. Campana (INAF-OAB), E. Cappellaro (INAF-OAPD), V. D'Elia (INAF-ASDC), F. Getman (INAF-OAC), A. Grado (INAF-OAC), G. Greco (Urbino University/INFN Firenze), L. Limatola (INAF-OAC), M. Lisi (INAF-OAR), L. Nicastro (INAF-IASF Bo), E. Palazzi (INAF-IAFS Bo), E. Pian (SNS-Pisa), S. Piranomonte (INAF-OAR), L. Pulone (INAF-OAR), A. Rossi (INAF-IASF Bo), G. Stratta (Urbino University/INFN Firenze), G. Tagliaferri (INAF-OAB), V. Testa (INAF-OAR), L . Tomasella (INAF-OAPD), S. Yang (INAF-OAPD), E. Brocato (INAF-OAR) on behalf of GRavitational Wave Inaf TeAm report: We carried out observations of LIGO/Virgo G268556 (LVC, GCN 20364) with the 0.9m Schmidt telesope located at the Campo Imperatore Observatory (Italy). The observations were taken in the r-sloan band on 2017-01-04 between 18:49:58 UT and 20:31:15 UT (8.6-10.3 hours after the trigger) under poor sky conditions. The covered area of ~ 6 square degrees captured a containment probability of ~1% of the LALInference map (LVC, GCN 20385). The area is divided in 5 pointings of 1.15x1.15 degrees and 120 sec exptime each. The pointing sequence was generated using the GWsky script (https://github.com/ggreco77/GWsky) starting from the high probability region of the bayestar skymap and taking into account the airmass. The 5 pointings are centered on the following coordinates RA, Dec (J2000): 131.6290 +47.8526 131.6304 +48.8528 132.9895 +47.8364 132.9902 +48.8390 132.9896 +49.8408 A preliminary analysis of these data reveals no obvious candidate counterpart down to a 3sigma limiting magnitude r ~ 17.0 (AB, calibrated against the SDSS DR13). //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20428 SUBJECT: LIGO/Virgo G268556: VLA follow-up of iPTF17cw DATE: 17/01/11 15:39:47 GMT FROM: Alessandra Corsi at Texas Tech U. A. Corsi (TTU), M.M. Kasliwal (CalTech), S.B. Cenko (NASA/GSFC), D.A. Frail (NRAO) report on behalf of a larger collaboration: We observed the position of the broad-lined type Ic supernova iPTF17cw (Kasliwal et al. LVC GCN#20398; Kupfer et al. LVC GCN#20419)located in the error region of LIGO/ Virgo G268556 (LVC GCN#20364) with the Karl G. Jansky Very Large Array (VLA) in its A configuration. The observations started on 10 Jan 2017 02:51:16 UTC, ended on 10 Jan 2017 03:51:00 UTC, and were carried out in C-band (central frequency of about 6 GHz). A provisional reduction of our data shows a radio source located at the position of iPTF17cw. For this source, we measure a radio flux of (38.1+/-7.3) uJy at 6.2 GHz. We caution that at the present time we do not know whether this source is variable. Further observations are planned. We thank the VLA staff for rapidly executing these observations. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20430 SUBJECT: LIGO/Virgo G268556: Additional GROWTH follow up observation of iPTF Optical Transient Candidates DATE: 17/01/11 17:14:40 GMT FROM: Mansi M. Kasliwal at Caltech R. Itoh, Y. Tachibana, Y. Saito, T. Yoshii, T. Fujiwara, Y. Ono, K. Morita, K. Saisho,Y. Yatsu, and N. Kawai (Tokyo Tech), C.-C., Ngeow (National Central University), L. P. Singer (NASA/GSFC), M. M. Kasliwal (Caltech) report on behalf of the GROWTH collaboration: We observed the field of the optical candidate reported by Singer et al. (LVC GCN 20401) with the 50cm Japanese telescope at Akeno Observatory (Japan) and the 40cm Telescope (SLT) with Apogee CCD at Lulin Observatory (Taiwan). We obtained the g, V, R and I bands image on 2017-01-09 and 2017-01-10 (UTC). The observed objects are listed below (3-sigma upper limits). We note that iPTF17fu, iPTF17fs, iPTF17ft, iPTF17fw, iPTF17gr, iPTF17gv and iPTF17gw contained the host galaxy but subtraction of host galaxy were not applied. #Time(UT) exposure[sec] ra[deg.] dec[deg.] V[mag.] V-error Name 2017-01-09T18:13:02 300.0 162.900034 +69.833971 18.99 0.13 iPTF17fs #Time(UT) exposure[sec] ra[deg.] dec[deg.] g[mag.] g-error R[mag.] R-error I[mag] I-error Name 2017-01-09T11:40:51.95 660.0 162.900034 +69.833971 >18.7 -- >19.0 -- >18.7 -- iPTF17fs 2017-01-09T16:31:03.65 2580.0 156.366148 +71.757620 16.46 0.07 15.46 0.02 14.97 0.03 iPTF17fw 2017-01-09T15:12:28.36 2640.0 159.042893 +69.146836 >19.1 -- >18.9 -- >18.5 -- iPTF17ge 2017-01-09T19:58:36.97 2040.0 199.058226 +76.521298 19.0 0.2 18.4 0.2 17.9 0.4 iPTF17gs 2017-01-09T12:48:30.17 2340.0 176.227516 +82.619152 16.52 0.07 15.49 0.03 14.87 0.03 iPTF17gv 2017-01-09T18:31:04.09 1380.0 178.409537 +72.864968 17.6 0.2 16.59 0.09 15.89 0.04 iPTF17gw 2017-01-09T19:07:24.90 1560.0 194.925476 +75.016124 19.9 0.2 >19.7 -- >18.7 -- iPTF17hh 2017-01-09T17:31:38.92 1920.0 180.885869 +72.050360 18.7 0.3 18.7 0.4 18.5 0.5 iPTF17hi 2017-01-09T19:48:39.40 480.0 191.763759 +76.839773 19.0 0.2 18.5 0.2 >18.1 -- iPTF17gt 2017-01-09T13:02:59.53 480.0 165.400920 +68.097753 >17.3 -- >18.0 -- >17.4 -- iPTF17hc 2017-01-10T18:52:33.53 1980.0 201.323053 +78.426314 16.23 0.09 15.21 0.03 14.84 0.03 iPTF17ft 2017-01-10T20:41:03.31 300.0 235.823172 +74.750334 18.8 0.3 17.6 0.2 17.0 0.2 iPTF17gm 2017-01-10T20:03:36.84 1920.0 232.045095 +74.611299 19.5 0.4 18.8 0.3 17.0 0.2 iPTF17gn 2017-01-10T19:41:27.53 480.0 195.818782 +80.173138 >18.9 -- >18.5 -- >18.0 -- iPTF17hf 2017-01-10T12:35:41.66 1140.0 192.417627 +80.149750 17.52 0.07 16.14 0.03 15.54 0.03 iPTF17fu 2017-01-10T18:12:54.94 2100.0 193.895770 +79.226903 17.51 0.04 16.22 0.02 15.64 0.02 iPTF17gr 2017-01-10T15:12:41.65 2340.0 194.101611 +78.204729 19.6 0.3 18.6 0.2 iPTF17gu Observations of this source were taken as part of the GROWTH network ( http://growth.caltech.edu). //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20434 SUBJECT: LIGO/Virgo G268556: Early SWASP limits of ATLAS17aeu DATE: 17/01/11 22:56:15 GMT FROM: Danny Steeghs at U of Warwick/GOTO D.Steeghs, D.Pollacco, K.Ulaczyk, R.Cutter, R.West, A.Levan (U. Warwick), D.K. Galloway, E.Rol, E.Thrane (Monash U.), V.Dhillon, M.Dyer, S.Littlefair, E.Daw, J.Maund, J.Mullaney (U. Sheffield), G.Ramsay (Armagh O.), P.O'Brien, R.Starling (U. Leicester) On behalf of the GOTO collaboration: We have analysed our SWASP imaging related to G268556 (GCN #20364, spanning MJD 57758.043-57758.210) for evidence of ATLAS17aeu. Our first imaging window following G268556 spans 9-5 hours before the reported detections in Tonry et al. (GCN #20382) and end 1 hour before GRB170105A (GCN #20387). We do not find any evidence for an optical source at the ATLAS17aeu position. We combined 3 sets of images not affected by clouds and achieve the following 5-sigma upper limits: MJD (mid): g limit: r limit: 57758.05948013 >17.7 >17.0 57758.09198558 >17.6 >16.9 57758.20992235 >17.0 >16.3 These photometric limits were derived by crossmatching field stars with the APASS survey. Considering the reported optical flux evolution of ATLAS17aeu (GCN #20382, #20393, #20397, #20407, #20416) and extrapolating to earlier times, we would have expected to detect ATLAS17aeu if its peak optical flux preceded GRB170105A. Our non-detections thus further corroborate associating ATLAS17aeu with the optical afterglow of GRB170105A. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20437 SUBJECT: LIGO/Virgo G268556: Gemini spectra of Pan-STARRS1 transients DATE: 17/01/12 10:27:29 GMT FROM: S. J. Smartt at Queens U Belfast K. C. Chambers (IfA), T.-W. Chen (MPE), S. J. Smartt, (QUB), M. E. Huber (IfA), K. W. Smith (QUB), D. R. Young, D. E. Wright (QUB), M. Coughlin (Harvard), L. Denneau, H. Flewelling, A. Heinze, E. A. Magnier (IfA), A. Rest (STScI), B. Stalder (IfA), A. S. B. Schultz, C. W. Stubbs (Harvard) J. Tonry, C. Waters, R. J. Wainscoat, H. Weiland (IfA) Further to Chambers et al. GCN 20410, we report initial results of spectroscopic classifications. We used Gemini-North + GMOS (R400 grating, 4491-8778 Angs) on MJD = 57761 (2017 Jan 08) to target objects which had either evolving lightcurves (rising/falling) and/or no obvious host galaxy. We report three classifications : PS17fj is a SN Ia at redshift = 0.239 PS17fl is most likely a SN Ib/Ic at or before peak at z=0.018 PS17fn is most likely a young type SN II at z=0.074 Further details as follows PS17fj : The best matches are SN1999ef +7d (normal-Ia), SN2001fe +6d (normal-Ia). Reasonable fits are also found for the 91T-like SN2003fa 91T-like. With an absolute mag of -19.7 mag, this is brighter than normal Ia, but typical for 91T-like. There is no host in SDSS, but the deeper PS1 3Pi stack (Chambers et al. 2016 arXiv 16120.5560) , shows a faint source at r~22.6 which is likely a dwarf galaxy host. The source is now fading. PS17fl : The spectrum has strong emission lines from the r=18.47 host galaxy, giving the redshift of z=0.081. It is also close to the centre of the compact host in the PS1 reference frames (0.7 arcsec) and the GMOS spectrum is likely contaminated with continuum flux from the host as it is not resolved in the 2D images. The spectrum has a blue continuum, consistent with the host galaxy. If a galaxy continuum (matched to the SDSS colours) is subtracted then reasonable fits to the spectrum are found for a Ib or Ic SN at or before peak. It is possible it is still rising, as a fit to SN2005bf at -8days is reasonable. The distinct lack of Si II means a Ia is unlikely. It is currently i = 20.17, or M_i ~ -17.7. PS17fn : PS17fn shows a blue continumm and galaxy emission lines of H-alpha and [SII] at z = 0.074. There is a broad and shallow emission profile at the position of H-alpha. The spectrum is noisy below 5000Angs (restframe), but is rising with a continuum blackbody temperature around 10,000K There is no good match from either SNID and GELATO. It is likely a very young type II, which is consistent with the lightcurve rise of 0.6mag in 3 days. The current mag of i=20.27 corresponds to an absolute mag of M_i ~ -17.4. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20445 SUBJECT: LIGO/Virgo G268556: TZAC TAROT network observations with TRE/TCA/TCH DATE: 17/01/13 10:10:50 GMT FROM: Michel Boer at CESR-CNRS M. Boer, R. Laugier, K. Noysena (ARTEMIS - CNRS/UCA/OCA), A. Klotz (IRAP - CNRS/UPS) report on behalf of the TZAC collaboration. The TAROT network of telescopes has observed part of the error box of the GW trigger G268556 (Shawman et al., GCN 20364). The observations took place at TCA (TAROT OCA Calern observatory, France), TCH (TAROT Chile, ESO La Silla Observatory), and TRE (TAROT Les Makes Observatory, La Réunion Island, France) during their respective nights of January 5-6 and 6-7, 2017. The field of view of TCA and TCH is 1.86° (square), and 4.2° for TRE. 4 fields have been observed by TCA, 5 for TCH and 9 for TRE, resulting in a total of 175 sq. deg. explored in the error box. The source ATLAS17aeu (Tony et al., GCN 20382) was not included in our fields. The exposures lasted 120s with no filter, resulting in approximate limiting magnitude of R < 17 for TCA and TCH (depending on the conditions and Moon) and 16 for TRE. The list of the fields is given below. We have checked the TCA and TCH fields and found no new candidate astrophysical transient sources. Analysis is still underway for TRE. List of field centers (J2000): TCA (1.86° x 1.86°) #0 08h51m11s +47d58m55s #1 08h43m27s +46d02m16s #2 08h56m47s +49d53m15s #3 09h05m31s +52d01m07s TCH (1.86° x 1.86°) #0 23h49m18s -36d03m12s #1 23h58m29s -37d19m07s #2 00h08m10s -38d22m09s #3 00h17m47s -39d19m59s #4 23h34m38s -33d52m51s TRE (4.2° x 4.2°) 0 23h44m45s -35d28m08s 1 00h02m19s -37d20m19s 2 00h22m48s -39d26m19s 3 00h44m36s -42d01m15s 4 01h07m43s -43d40m09s 5 23h31m33s -32d11m14s 6 23h18m49s -28d00m31s 7 23h03m54s -24d30m28s 8 22h52m18s -20d50m51s //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20459 SUBJECT: LIGO/Virgo G268556: spectra of two nuclear transients PS17fr and PS17er DATE: 17/01/14 23:19:15 GMT FROM: S. J. Smartt at Queens U Belfast M. E. Huber (IfA), K. C. Chambers (IfA), T.-W. Chen (MPE), S. J. Smartt, (QUB), K. W. Smith (QUB), D. R. Young, D. E. Wright, E. Kankare, R. Kotak, C. Inserra (QUB), M. Coughlin (Harvard), L. Denneau, H. Flewelling, A. Heinze, E. A. Magnier (IfA), A. Rest (STScI), B. Stalder (IfA), A. S. B. Schultz, C. W. Stubbs (Harvard) J. Tonry, C. Waters, R. J. Wainscoat, H. Weiland (IfA) Further to our Pan-STARRS campaign (Smartt et al, GCN 20410) and classification of transients (Chambers et al. GCN 20437) we report spectra of two further objects at the cores of galaxies. -------------------------------------------------------------- PS17fr - possible luminous nuclear SN or TDE --------------------------------------------------------------- PS17fr was discovered coincident with the nucleus of an r=18.36 galaxy (SDSS J081152.10+252521.3), with a photometric redshift z=0.199. The magnitude on the first epoch MJD=57758.433 (from the difference image) was i=19.2, rising 0.6 mag in 3 days. A spectrum with the UH2.2m + SNIFS (R~1300, 3200-10000A) was taken on MJD=57997 and shows broad H-alpha, H-beta and He I 5876. The line profiles are asymmetric. The strong H-alpha has a width at half maximum of 5200 km/s, but is either multicomponent or significantly asymmetric with a red excess. Assuming the centroid of the peak velocity is representative of the host and transient, then z = 0.1862 +/- 0.0003. This implies an absolute magnitude of M_r = -21.1. The object may be a a superluminous supernova of type II or IIn. We note that it is within the volume defined by the LALInference 3D map, at a luminosity distance of 918 Mpc (Ho=69, Omega_M=0.3, Omega_Lam=0.7). As this is a nuclear transient, AGN activity is possible. But we see no strong [N II], [OIII] or [O II]. A weak feature close to, but not exactly at the expected position of [O III] 5007 is visible in the SNIFS data. Another spectrum is required to confirm. A tidal disruption event is also a possible explanation. In summary this is an unusually luminous transient within the LIGO skymap and at a distance consistent with the central 80% of the probability distribution. Further multi-wavelength follow-up is encouraged to determine its nature. Coords : 08:11:52.11 +25:25:21.4 (J2000) ------------------------------------------------------------- PS17er - probable AGN/Seyfert 2 variability ------------------------------------------------------------- PS17er is also a rising transient (now at i=20) at the core of the r=19.2 galaxy SDSS J084157.26+405507.6. A spectrum with Gemini-N+GMOS (R400 grating, 4491-8778 A) on 57764.4223666319 shows it to be at a redshift of z=0.4064 from the [O III] 4959/5007 Angs, implying M_g = -21.3. These lines have a resolved width of 700 km/s, and there is a broader (4000 km/s) H-beta line in emission. The ratio Log([OIII]/Hb) ~ 0.8, is normal for an AGN. In Pan-STARRS regular survey mode, we have seen various detections of i ~ 20 variability. Hence we consider this as likely ongoing Seyfert 2 activity, similar to episodes previously detected in PSST (Huber et al. 2015, ATel 7153). //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20473 SUBJECT: LIGO/Virgo G268556: Swift-XRT observations of iPTF17cw DATE: 17/01/16 19:47:25 GMT FROM: Phil Evans at U of Leicester P.A Evans (U. Leicester), A. Corsi (TTU), J.A. Kennea (PSU), S.D. Barthelmy (NASA/GSFC), A.P. Beardmore (U. Leicester), A.A. Breeveld (UCL-MSSL), D.N. Burrows (PSU), S. Campana (INAF-OAB), S.B. Cenko (NASA/GSFC), G. Cusumano (INAF-IASF PA), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB), V.D'Elia(ASDC), N. Gehrels (NASA/GSFC), P. Giommi (ASI), C. Gronwall (PSU), H.A. Krimm (CRESST/GSFC/USRA), N.P.M. Kuin (UCL-MSSL), A.Y. Lien (GSFC/UMBC), D. Malesani (DARK/NBI), F.E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), B. Mingo (U. Leicester), J.A. Nousek (PSU), S.R. Oates (U. Warwick), P.T. O'Brien (U. Leicester), J.P. Osborne (U. Leicester), C. Pagani (U. Leicester), K.L. Palmer (LANL), M. Perri (ASDC), J.L. Racusin (NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU), M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB), E. Troja (NASA/GSFC/UMCP), M.M. Kasliwal (Caltech), S.R. Kulkarni (Caltech), D.A. Frail (NRAO), N.T. Palliyaguru (TTU) report on behalf of the Swift and iPTF GW follow-up teams: Swift has performed follow-up observations of the source iPTF17cw (Kasliwal et al., LVC Circ. 20398; Kupfer et al., LVC Circ. 20419). Swift-XRT collected 1.3 ks of data from 790.6 ks to 802.8 ks after the GW trigger. No X-ray events were detected at the location of iPTF17cw. The 3-sigma upper limit at this location was 5.3e-3 ct/sec (0.3-10 keV). Assuming a typical AGN spectrum (NH=3e20 cm^-2, Gamma=1.7) this corresponds to a flux of 2.19e-13 erg cm^-2 s^-1. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20485 SUBJECT: LIGO/Virgo G268556: RATIR Observation of iPTF Candidates DATE: 17/01/20 05:10:34 GMT FROM: V. Zachary Golkhou at ASU/SESE--RATIR Zach Golkhou (ASU), Nat Butler (ASU), Neil Gehrels (GSFC), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Eleonora Troja (GSFC), and Alan M. Watson (UNAM) report: We observed a number of iPTF candidates (Kasliwal et al. LVC GCN#20398) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir from 2017/01 11.28--11.30 UTC (6.85 days since the GW trigger; Shawhan et al. LVC GCN #20364) and again from 2017/01 12.44--12.46 UTC. At positions consistent with each iPTF source position, we report riZY photometry for the probable host galaxy from the first epoch. In comparison with the SDSS DR9 and 2MASS catalogs, we obtain: # Source r (dt_r) i (dt_i) Z (dt_Z) Y (dt_Y) iPTF17ce 19.84+/-0.04 (0.36) 18.92+/-0.02 (0.36) 18.37+/-0.02 (0.07) 18.35+/-0.03 (0.07) iPTF17ck 18.17+/-0.01 (0.71) 17.59+/-0.01 (0.71) 17.63+/-0.01 (0.15) 17.33+/-0.01 (0.15) iPTF17dz ... 19.09+/-0.01 (0.51) 19.30+/-0.03 (0.22) 19.23+/-0.04 (0.22) iPTF17ef 19.18+/-0.02 (1.07) 18.92+/-0.02 (1.07) 18.86+/-0.03 (0.22) 18.59+/-0.02 (0.22) iPTF17ei 16.77+/-0.01 (1.38) 16.37+/-0.01 (1.38) 16.17+/-0.01 (0.29) 15.97+/-0.01 (0.29) These magnitudes are in the AB system and are not corrected for Galactic extinction in the source direction. Exposure times (dt) are reported in hours. We find no evidence for variation in flux at >2-sigma confidence from an image subtraction analysis between our two epochs. We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20493 SUBJECT: LIGO/Virgo G268556: Global MASTER Net 21 OTs detection DATE: 17/01/21 11:11:58 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs N.Tyurina, V.M. Lipunov, O.Gress, E. Gorbovskoy, V.G. Kornilov, P.Balanutsa, A.Kuznetsov, V.Shumkov, M.I.Panchenko, A.V.Krylov, I.Gorbunov Lomonosov Moscow State University, Sternberg Astronomical Institute D.Buckley, S. Potter, M. Kotze South African Astronomical Observatory R. Rebolo, M. Serra-Ricart, G. Israelian, N.Lodiu The Instituto de Astrofisica de Canarias A. Tlatov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory N.M. Budnev, O. Gress, K. Ivanov Irkutsk State University V.Yurkov, Yu.Sergienko, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk 1) MASTER OT J072347.17+041144.0 discovery MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 07h 23m 47.17s +04d 11m 44.0s on 2017-01-09.07133 UT. The OT unfiltered magnitude is 17.5m (mlim=19.3). The OT is seen in 2 images. There is no minor planet at this place. We have reference image on 2015-05-17.70236 UT with unfiltered mlim= 19.0m. Spectral observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/072347.17041144.0.png 2) MASTER OT J073310.71-012307.3 discovery - dwarf nova outburst MASTER-SAAO auto-detection system discovered OT source at (RA, Dec) = 07h 33m 10.71s -01d 23m 07.3s on 2017-01-15.07407 UT. The OT unfiltered magnitude is 18.0m (mlim=18.7). The OT is seen in 2 images. The second image on 2017-01-15.07656 has m_OT=18.3 (possible UGSU type?). There are 2 images on 2017-01-18 18:44:23UT (MASTER-Kislovodsk) with m_OT=18.8 (mlim=19.8). We have reference images on 2016-10-13.09314 UT with unfiltered mlim= 19.0m (MASTER-SAAO), on 2013-02-11 18:07:22UT with mlim=19.7(MASTER-Kislovodsk). There were previous outbursts in MASTER databases: on 2013-12-27 20:41:41.17 with m_OT=18.5 (2 images in MASTER-Kislovodsk) on 2015-12-17 17:22:22.72 with m_OT=17.5 (2 images in MASTER-Tunka) Spectral observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/073310.71-012307.3.png 3) MASTER OT J080700.56+162008.7 detection MASTER-IAC auto-detection system discovered OT source at (RA, Dec) = 08h 07m 00.56s +16d 20m 08.7s on 2017-01-19.13492 UT. The OT unfiltered magnitude is 19.3m (limit 19.8m). The OT is seen in 2 images (2017-01-19 03:14:17.943, 03:10:37.397). We have reference image without OT on 2016-11-09.20727 UT with unfiltered magnitude limit 20.0m. There is Sloan star with gmag=22.9, r=21.2, i=19.6 http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=&-out.add=_r&-out.add=_RAJ%2C_DEJ&-sort=_r&-to=&-out.max=20&-meta.ucd=2&-meta.foot=1&-c=121.75233333333+16.335738888889&-c.rs=5 Spectral observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/080700.56162008.7.png 4) MASTER OT J075227.62+113311.6 discovery - QSO flare MASTER-SAAO auto-detection system discovered OT source at (RA, Dec) = 07h 52m 27.62s +11d 33m 11.6s on 2017-01-08.99171 UT. The OT unfiltered magnitude is 18.5m (mlim=19.5). The OT is seen in 8 images. There is no minor planet at this place. We have reference image on 2015-05-25.70605 UT with unfiltered mlim= 19.4m. Spectral observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/075227.62113311.6.png 5) MASTER OT J063256.50-212333.4 detection - possibly UVCet flare MASTER-IAC auto-detection system discovered OT source at (RA, Dec) = 06h 32m 56.50s -21d 23m 33.4s on 2017-01-18.91929 UT. The OT unfiltered magnitude is 17.6m (limit 19.7m). The OT is seen in 5 images, UVCet preliminary (J-K=0.8) 2017-01-18 21:41:32.849 16.0 2017-01-18 21:45:12.99 16.2 2017-01-18 21:48:58.848 16.5 2017-01-18 22:03:47.638 17.5 We have reference image without OT on 2015-12-18.08299 UT with unfiltered magnitude limit 20.7m. Spectral observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/063256.50-212333.4.png 6) MASTER OT J074554.47+283123.8 discovery MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 07h 45m 54.47s +28d 31m 23.8s on 2017-01-05.04067 UT. The OT unfiltered magnitude is 18.4m (mlim19.7=). The OT is seen in 2 image. We have reference image on 2017-01-05.03814 UT with unfiltered mlim= 19.6m. There is no known objects inside 3" in VIZIER database, but there is very faint source at Sloan image (rmag<23) Spectral observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/074554.47283123.8.png 7) MASTER OT J081016.59+335347.5 discovery - PSN in 1.9"W, 2.4"S of PGC2040653 MASTER-Kislovodsk auto-detection system discovered OT source at (RA, Dec) = 08h 10m 16.59s +33d 53m 47.5s on 2017-01-08.15065 UT. The OT unfiltered magnitude is 17.0m (limit 17.6m). The OT is seen in 2 images. There is no minor planet at this place. We have reference image without OT on 2016-11-02.89640 UT with unfiltered magnitude limit 19.8m. Spectral observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/081016.59335347.5.png 8) MASTER103001.37+680122.3 discovery - dwarf nova outburst? MASTER-Kislovodsk auto-detection system discovered OT source at (RA, Dec) = 10h 30m 01.37s +68d 01m 22.3s on 2017-01-07.12512 UT. The OT unfiltered magnitude is 18.5m (limit 20.3m). The OT is seen in 2 image. There is no minor planet at this place. There is m_OT=20.1 on 2017-01-06 02:18:08UT (dwarf nova?), it means amplitude of current outburst more then 1.5mag Spectral observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/103001.37680122.3.png 9) MASTER OT J073330.60+203432.7 discovery - dwarf nova outburst? MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 07h 33m 30.60s +20d 34m 32.7s on 2017-01-18.65299 UT. The OT unfiltered magnitude is 18.1m (limit 19.5m). The OT is seen in 2 images. There is no minor planet at this place. We have reference image without OT on 2017-01-05 20:20:59 with mlim=19.8, on 2011-11-28.89471 UT with unfiltered magnitude limit 20.0m. There is Sloan blue star with rmag=19.80, it means current outburst amplitude more then 1.9m http://skyserver.sdss.org/dr9/en/tools/quicklook/quickobj.asp?id=1237660564038877690 Spectral observations are required. 10) MASTER OT J084411.47+670931.6 - flare, >1.5mag Ampl MASTER-Kislovodsk auto-detection system discovered OT source at (RA, Dec) = 08h 44m 11.47s +67d 09m 31.6s on 2017-01-20.72236 UT. The OT unfiltered magnitude is 19.1m (limit 20.1m). The OT is seen in 6 images. There is no minor planet at this place. We have reference image without OT on 2012-10-20.89072 UT with unfiltered magnitude limit 19.8m. There is USNO B1 star with R2=20.6, APM blue mag=22.04, it means MASTEr W=20.9, Ampl of current outburst >1.5 Spectral observations are required. 11) MASTER OT J102428.83+641859.1 discovery - QSO flare MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 10h 24m 28.83s +64d 18m 59.1s on 2017-01-07.81205 UT. The OT unfiltered m is 17.8m (limit 20.2m). The OT is seen in 23 images in history. Last QSO (Sloan red=20.5) outbursts detected by MASTER: 2015-03-09 17:00:10.572 19.0 2017-01-05 14:58:23.595 17.9 2017-01-07 19:29:21.053 17.8 2017-01-07 19:45:55.751 17.8 We have reference image without OT on 2016-08-20 18:40:31 with mlim=18.7, on 2015-07-10.70841 UT with unfiltered mlim=19.6m. Spectral observations are required. 12) MASTER OT J075227.69+113313.2 discovery - QSO flare MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 07h 52m 27.69s +11d 33m 13.2s on 2017-01-06.70229 UT. The OT magnitude in unfiltered is 18.4m (limit 19.0m). The OT is seen in 2 images. We have reference image without OT on 2015-10-19.86133 UT with unfiltered 19.3m. There is Sloan source in 1" with red mag 19.819, GALEX source(accretion), QSO candidate (Richards+, 2015). Spectral observations are required. 13) MASTER OT J081506.13+381123.3 discovery - PSN in 11"E,2.8"N of PGC2120251 MASTER-Kislovodsk auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 08h 15m 06.13s +38d 11m 23.3s on 2017-01-16.01742 UT. The OT unfiltered magnitude is 16.9m (limit 18.6m). The OT is seen in 2 images in MASTER-Kislovodsk and in 2 in MASTER-SAAO (2017-01-18 00:38:36UT). There is no minor planet at this place. We have reference image without OT on 2016-11-29.91344 UT with unfiltered magnitude limit 20.1m. Spectral observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/081506.13381123.3.png 14) MASTER OT J074928.00+190452.3 discovery ( 2017-01-19 22:23:28.536UT, mOT=17.4) = current outburst of UG (dwarf nova) CSS 090331:074928+190452 15) MASTER OT J051306.58-261951.9 detection (2017-01-11 23:36:39.213, m_OT=16.1) = current outburst of UGSU ASASSN-14kf 16) MASTER OT J224258.06-194551.5 detection (2017-01-04 19:44:11.46, m_OT=13.7) = current outburst of UGSU (Dwarf nova) ASASSN-14hs 17) MASTER OT J101511.20+812418.1 discovery () = current outburst of dwarf nova ASASSN-15gq / UGSU 18) MASTER OT J101813.00+715542.7 discovery 2017-01-04 20:20:00.35UT, m_OT=15.1) = current outburst of dwarf nova CI UMa (UGSU) 19) MASTER OT J075107.56+300628.0 discovery (2017-01-06 18:33:32.877, m_OT=15.3) = current outburst of dwarf nova SDSS J075107.50+300628.4 20) MASTER OT J105811.78+811432.6 discovery - BLA flare in GW170401 field , publishied GCN20392 21) MASTER OT J090021.21+635049.7 - SN, publishied GCN20381 //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20507 SUBJECT: LIGO/Virgo G268556/GW170104: MAXI/GSC observations DATE: 17/01/23 02:51:51 GMT FROM: Motoko Serino at RIKEN/MAXI M. Serino (RIKEN), N. Kawai, S.Sugita (Tokyo Tech), H. Negoro (Nihon U.), S. Ueno, H. Tomida, S. Nakahira, M. Ishikawa, Y. Sugawara (JAXA), Y. E. Nakagawa (JAMSTEC), T. Mihara, M. Sugizaki, W. Iwakiri, M. Shidatsu, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN), N.Isobe, T. Yoshii, Y. Tachibana, Y. Ono, T. Fujiwara, S. Harita, Y. Muraki (Tokyo Tech), A. Yoshida, T. Sakamoto, Y. Kawakubo, Y. Kitaoka (AGU), H. Tsunemi, R. Shomura (Osaka U.), M. Nakajima, K. Tanaka, T. Masumitsu, T. Kawase (Nihon U.), Y. Ueda, T. Kawamuro, T. Hori, A. Tanimoto, S. Oda (Kyoto U.), Y. Tsuboi, Y. Nakamura, R. Sasaki (Chuo U.), M. Yamauchi, K. Furuya (Miyazaki U.), K. Yamaoka (Nagoya U.) report on behalf of the MAXI team: We examined the MAXI/GSC all-sky X-ray images (2-20 keV) obtained in the orbit and the day after the LVC trigger G268556/GW170104 at 2017-01-04 10:11:58.599 UTC (GCN 20364). In the 92-min orbit, MAXI/GSC scanned more than 80% of the whole sky, which includes 89.3% of the 90% regions in the bayestar skymap. One day image covers 95.2% of the 90% regions in the bayestar skymap. No significant new source was found in these images. The upper limits for the X-ray flux are different depending on the part of the sky. For instance, typical 2-20 keV 1-sigma (3-sigma) upper limits obtained from the one-orbit and oneday images are 19 (56) mCrab and 5 (16) mCrab, respectively. MAXI/GSC also observed the position of GRB 170105A (GCN Circ. 20377, 20390, 20406). The first scan after the burst was at 2017-01-05T06:47 (UT). No significant emission was observed at the position at the scan. The 1-sigma (3-sigma) upper limits in 2-20 keV are 18 (54) mCrab. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20517 SUBJECT: LIGO/Virgo G268556: ANTARES upper limits DATE: 17/01/24 18:01:13 GMT FROM: Damien Dornic at CPPM/CNRS M. Ageron (CPPM/CNRS), B. Baret (APC/CNRS), A. Coleiro (APC/Universite Paris Diderot), D. Dornic (CPPM/CNRS), A. Kouchner (APC/Universite Paris Diderot), T. Pradier (IPHC/Universite de Strasbourg) report on behalf of the ANTARES Collaboration: The ANTARES Collaboration has reported in GCN 20370, no up-going muon neutrino candidate event within the 90% contour during a +/- 500s time-window centered on the G268556 event time. We use this non-detection to derive a neutrino (nu_mu+antinu_mu) spectral fluence instantaneous upper limit at 90% C.L. (phi_0 in GeV/cm^2), defined as dN/dE = phi_0* E^{-2} assuming a E^{-2} neutrino spectrum. The result is reported in https://www.cppm.in2p3.fr/~dornic/events/G268556_fluenceE2.png (gwantares/ANT@GW) as a function of the source direction. These neutrino fluence limits range between 1 and 3 GeV/cm^{2} depending on the source direction. For a E^{-2} neutrino spectrum, 90% of ANTARES signal neutrinos are in the energy range from 2.8 TeV to 3.2 PeV (mean value over the sky). From the 3D GW localization and the neutrino spectral fluence upper-limits, the preliminary upper limits on the total energy radiated in high-energy neutrinos over the GW skymap are computed for the progenitor of G268556 as a function of the source direction assuming a a E^{-2} neutrino spectrum integrating in the range [100 GeV-100 PeV]: https://www.cppm.in2p3.fr/~dornic/events/G268556_energyE2.png (gwantares/ANT@GW). The total neutrino emission limits range between 10^{54} and 10^{55} ergs. ANTARES, being installed in the Mediterranean Deep Sea, is the largest neutrino detector in the Northern Hemisphere. It is primarily sensitive to astrophysical neutrinos in the TeV-PeV energy range. At 10 TeV, the median angular resolution for muon neutrinos is below 0.5 degrees. In the range 1-100 TeV, ANTARES has the best sensitivity to a large fraction of the Southern sky. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20553 SUBJECT: LIGO/Virgo G268556: FLOYDS Spectrum of iPTF17cf/PS17fr Favors an AGN Classification DATE: 17/01/28 00:45:29 GMT FROM: Griffin Hosseinzadeh at LCOGT G. Hosseinzadeh, I. Arcavi, D. A. Howell, C. McCully (Las Cumbres Obs./UCSB), and S. Valenti (UC Davis) report a spectrum of EM candidate iPTF17cf/PS17fr (GCN 20398 & 20410) associated with gravitational wave event G268556 (GCN 20364) obtained 2017 January 27.3 UT with the robotic FLOYDS instrument mounted on the Las Cumbres Observatory 2-meter telescope on Haleakala, Hawai'i. The spectrum shows broad H-alpha and H-beta emission and possible narrow [O III] emission at redshift z~0.19, suggesting an AGN classification (c.f. GCN 20459). //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20735 SUBJECT: LIGO/Virgo G268556: ATLAS17aeu / GRB170105A - TNG host galaxy detection DATE: 17/02/25 12:26:47 GMT FROM: Enzo Brocato at INAF-OA Roma A. Melandri (INAF-OAB), S. Piranomonte (INAF-OAR), M. Branchesi (Urbino University/INFN Firenze), S. Covino (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (INAF-ASDC), A. Rossi, (INAF-IASF Bo), L. Amati (INAF-IASF Bo), L. A. Antonelli, S. Ascenzi (INAF-OAR), M.T. Botticella (INAF-OAC), S. Campana (INAF-OAB), E. Cappellaro (INAF OAPd), F. Getman, A. Grado (INAF-OAC), G. Greco (Urbino University/INFN Firenze) , L. Limatola (INAF-OAC), M. Lisi (INAF-OAR), L. Nicastro (INAF-IASF Bo), E. Palazzi (INAF-IASF Bo), E. Pian (SNS-Pisa), L. Pulone (INAF-OAR), G. Stratta (Urbino University/INFN Firenze), G. Tagliaferri (INAF-OAB), V. Testa (INAF-OAR), L. Tomasella, S. Yang (INAF-OAPD), E. Brocato (INAF-OAR) on behalf of GRavitational Wave Inaf TeAm (GRAWITA) report: We observed the field of the transient ATLAS17aeu (Tonry et al., GCN Circ. 20382) recognized to be the possible afterglow of GRB170105A (Kasliwal et al., GCN 20393), previously reported by POLAR (Marcinkowski et al., GCN 20387) and detected by AstroSAT CZTI (Sharma et al., GCN 20389). ATLAS17aeu was proposed to be associated with the galaxy SDSS J091312.36+610554.2 z=0.199, at a projected distance of 75 kpc (Tonry et al., GCN Circ. 20382). We used the TNG telescope equipped with DoLoRES in imaging mode. A 70 min exposure (r`-sloan filter) was obtained starting on 24/02/2017 20:48:16 UT. At the position of the afterglow we identify an extended source, which we propose to be the GRB host galaxy. The aperture photometry of the object is r = 24.23 +/- 0.20, calibrated against nearby SDSS stars. A preliminary analysis shows that this ATLAS17aeu measurement is 2 magnitudes or more brighter than the value expected by the afterglows decay fit obtained from previous observations. We thank the TNG staff, in particular Gloria Andreuzzi and Gianni Mainella for conducting the observations and the visiting astronomer Matteo Pinomonti for devoting his observing time to this target. [GCN OPS NOTE(02mar17): Per author's request, the Subject line was changed from "G274296" to "G268556".] //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21056 SUBJECT: LIGO/Virgo G268556: Refined localization from CBC parameter estimation DATE: 17/05/02 14:16:10 GMT FROM: Christopher Berry at U of Birmingham/LVC The LIGO Scientific Collaboration and Virgo Collaboration report: We have completed a Bayesian parameter-estimation analysis of the GW candidate G268556 (GCN 20364) under the assumption that the signal arises from a compact binary coalescence (CBC) and using the latest calibration of the GW strain data. The data are still found to be consistent with a binary black hole merger. A refined sky localization is now available and can be retrieved from GraceDB (https://gracedb.ligo.org/events/G268556): * LALInference_f.fits.gz, produced using a coherent Bayesian analysis (Veitch et al. PRD 91, 042003) of the full GW signal including spin precession, and incorporating the potential effects of calibration errors. We regard this LALInference sky map as the most authoritative localization for this event. The localization is similar in structure to previous ones (GCN 20364 and 20385), with two arcs tracing part of the annulus set by the 3 ms delay in arrival time between the Hanford and Livingston observatories. The differences compared to previous localizations are primarily a consequence of the improved calibration of the data. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21153 SUBJECT: LIGO/Virgo G268556: VERITAS Very-High-Energy Gamma-Ray Observations DATE: 17/05/27 00:20:02 GMT FROM: David A. Williams at UC Santa Cruz Reshmi Mukherjee (Barnard College and Columbia University) reports on behalf of the VERITAS Collaboration: The VERITAS gamma-ray telescope array was used to perform follow-up observations of the localization region for the gravitational-wave candidate G268556 between 2017-01-05 07:14:53 and 11:39:39 UTC. During this period, the northern section of the 50% containment region for the event was observable at >50° elevation from the VERITAS site and 39 consecutive exposures were performed to tile the localization region using the 3.5°-diameter field-of-view of the VERITAS telescopes. Each pointing was observed for 5 minutes, with an average spacing between pointings of 1.83° to allow some overlap between neighboring fields. The observations cover approximately 27% of the containment probability of the event. Unfortunately, the majority of the exposures were affected by the presence of clouds. Furthermore, one of the four VERITAS telescopes was offline during the final two-thirds of the observations, decreasing the sensitivity by ~20%. Preliminary results from the analysis of the VERITAS data show no significant evidence of gamma-ray emission. Observations performed by VERITAS under clear skies using a similar observational strategy have been able to detect the Crab Nebula at high significance (>10 standard deviations) using similar exposures with all four telescopes. Under ideal conditions, these observations of G268556 would have been sensitive to a gamma-ray source with a flux greater than ~50% of the Crab Nebula, i.e., greater than ~3 x 10^{-10} cm^{-2} s^{-1} above 100 GeV, during the time period and in the region of sky observed. However, the sensitivity of VERITAS was reduced due to the poor weather conditions, and it is challenging to set specific limits at this time. Questions regarding the VERITAS observations should be directed to Reshmi Mukherjee (muk@astro.columbia.edu). VERITAS (the Very Energetic Radiation Imaging Telescope Array System) is a very-high-energy gamma-ray observatory located at the Fred Lawrence Whipple Observatory in southern Arizona, USA. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21158 SUBJECT: LIGO/Virgo G268556/GW170104: Konus-Wind observations DATE: 17/05/28 15:48:23 GMT FROM: Dmitry Svinkin at Ioffe Institute D. Svinkin, S. Golenetskii, R.Aptekar, D. Frederiks, P. Oleynik, M. Ulanov, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline, on behalf of the Konus-Wind team, report: Konus-Wind (KW) was observing the whole sky at the time of the LIGO event G268556/GW170104 (2017-01-04 10:11:58.599 UTC, hereafter T0; LIGO/VIRGO Collaboration GCN Circ. 20364). No triggered KW event happened from ~2 day before to ~1 day after T0. The closest waiting-mode event was ~1.4 days before T0. Using waiting-mode data within the interval T0 +/- 100 s, we found no significant (> 5 sigma) excess over the background in both KW detectors on temporal scales from 2.944 s to 100 s. We estimate an upper limit (90% conf.) on the 10 keV – 10 MeV fluence to 9.2x10^-7 erg/cm^2 for a burst lasting less than 2.944 s and having a typical KW short GRB spectrum (an exponentially cut off power law with alpha =-0.5 and Ep=500 keV). For a typical long GRB spectrum (the Band function with alpha=-1, beta=-2.5, and Ep=300 keV), the corresponding limiting peak flux is 3.3x10^-7 erg/cm^2/s (10 keV - 10 MeV, 2.944 s scale). All the quoted values are preliminary. The information was originally included in a LVC Circular along with other results at 17/03/02 14:42:59 GMT. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21159 SUBJECT: LIGO/Virgo G268556: BSA radio observations at 110 MHz DATE: 17/05/28 19:00:29 GMT FROM: Alexei Pozanenko at IKI,Moscow A.S. Pozanenko (IKI), V.A. Samodurov (HSE, PRAO LPI), M.O. Toropov (JSC Business Automation), A.E. Rodin (PRAO LPI), P.Yu. Minaev (IKI), S.V. Logvinenko (PRAO LPI), V.V. Oreshko (PRAO LPI) report on behalf of IKI-GW follow-up collaboration: We have investigated daily data survey of BSA radiotelescope operated at 109.0-111.5 MHz in a survey mode (Samodurov, et al. 2015, http://adsabs.harvard.edu/abs/2015OAP....28..242S). At the time of trigger of G268556 (LIGO Scientific Collaboration, GCN 20364) the diagram of BSA was 10:39 hours after and 13:21 hours before passing of the localization area of G268556 between Dec=+15.0 deg and Dec=+42.0 deg (i.e. most sensitive part of the BSA diagram). We do not detect any source brighter than 3 Jy (exposure of 300 s) on (UT) 2017-01-04 23:33:00, i.e. 13:21 hours after the G268556 trigger in Declination range between +15.0 and +42.0 degrees. We used previous passages of the localization region through the diagram to estimate possible variability of the flux and to estimate the upper limit. Result reported is preliminary and might be refined. //////////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21160 SUBJECT: LIGO/Virgo G268556: optical observations and classification of Pan-STARRS1 transients DATE: 17/05/28 21:05:39 GMT FROM: Alexei Pozanenko at IKI,Moscow A. Pozanenko (IKI), A. Volnova (IKI), E. Mazaeva (IKI), E. Klunko (ISTP), A. Kusakin (AFIF), I. Reva (AFIF) on behalf of IKI-GW follow-up collaboration: We report results of photometric observations and possible classifications of Pan-STARRS1 transients PS17dp, PS17fl, PS17fn, PS17gl (Smartt et al, GCN 20410) detected in the LIGO G268556 localizations (LIGO Scientific Collaboration, GCN 20364). Observations were conducted using telescopes/observatories AZT-33IK/Mondy and Zeiss-1000/TSHAO. =============== PS17dp RA 09:00:51.09 Dec +45:26:44.3 We observed the source PS17dp taking 5 observational sets in different epochs between Jan. 19 and 24. All observations were performed with filter R. The photometry is based on nearby SDSS stars. Date UT start Filter MJD mag err 2017-01-19 18:24:02 R 57770.77716 16.93 0.04 2017-01-21 17:56:26 R 57774.75795 16.91 0.05 2017-01-22 17:40:22 R 57775.74680 16.90 0.05 2017-01-23 17:04:07 R 57776.72092 16.93 0.05 2017-01-24 21:17:52 R 57777.89783 17.02 0.04 The source is fading during our observations. There is an SDSS galaxy J090050.96+452642.7 at the position of the source with r = 17.280 +/- 0.006 and R = 17.050 +/- 0.015 (Lupton 2005 transformation equations) which might be a host galaxy of the transient. At the last observational epoch the source faded to the host galaxy level within 1 sigma. =============== PS17fl RA 08:02:09.73 Dec +28:49:44.7 We observed the source PS17fl taking 9 observational sets in different epochs between January 17 and March 28. All observations were performed with filter R. The photometry is based on nearby SDSS stars. Date UT start Filter MJD mag err 2017-01-17 16:24:04 R 57770.69727 18.15 0.10 2017-01-19 16:52:12 R 57772.71590 18.16 0.02 2017-01-21 15:21:07 R 57774.65356 18.20 0.02 2017-01-22 15:47:17 R 57775.66825 18.18 0.02 2017-01-23 15:39:48 R 57776.66306 18.17 0.02 2017-01-24 19:43:15 R 57777.82865 18.21 0.03 2017-01-25 16:24:35 R 57778.69277 18.18 0.03 2017-01-28 18:32:47 R 57781.78667 18.12 0.02 2017-03-28 17:18:32 R 57840.73404 18.22 0.03 The brightness of the source slowly decreases and in our last observational set has a magnitude consistent within 2 sigma with that of its host galaxy SDSS J080209.69+284945.3 (Chambers et al. GCN 20437) with r = 18.47 +/- 0.01 and R = 18.29 +/- 0.02 (Lupton 2005 transformation equations). If SN Ib/Ic (suggested by Chambers et al. GCN 20437) then maximum can be between MJD 57761.4876 and 57770.69727 and therefore could be related to G268556 event. =============== PS17fn RA 08:05:51.40 Dec +28:42:51.9 We observed the source PS17fn taking 8 observational sets in different epochs between Jan. 17 and 28. All observations were performed with filter R. The photometry is based on nearby SDSS stars. Date UT start Filter MJD mag err 2017-01-17 17:52:24 R 57770.75515 19.51 0.16 2017-01-19 17:34:47 R 57772.74354 19.18 0.04 2017-01-21 16:15:49 R 57774.68807 19.11 0.04 2017-01-22 16:19:52 R 57775.69088 19.15 0.04 2017-01-23 16:32:34 R 57776.69970 19.15 0.40 2017-01-24 20:05:57 R 57777.84441 19.31 0.05 2017-01-25 16:53:02 R 57778.71114 19.33 0.04 2017-01-28 19:15:36 R 57781.80806 19.31 0.07 There is an SDSS galaxy J080209.69+284945.3 at the position of the source with r = 19.801 +/- 0.032 and R = 19.612 +/- 0.063 (Lupton 2005 transformation equations) which might be a host galaxy of the transient. The source is rising above the host level for more then 3 sigma, than fading.The photometry of the source might be contaminated by a nearby galaxy J080551.85+284253.6 in 6 arcseconds to the East of the source. The temporal behavior of the transient allows to confirm it to be a supernova (Chambers et al. 20437) with the maximum around of MJD = 57774.68807 and therefore the source is inconsistent with the G268556 trigger. =============== PS17gl RA 08:34:50.85 Dec +61:13:02.2 We observed the source PS17fl taking 5 observational sets in different epochs between Jan. 19 and 25. All observations were performed with filter R. The photometry is based on nearby SDSS stars. Date UT start Filter MJD mag err 2017-01-19 18:59:34 R 57772.80185 17.38 0.03 2017-01-21 16:48:39 R 57774.71087 17.39 0.03 2017-01-22 16:57:34 R 57775.71707 17.40 0.03 2017-01-24 20:36:10 R 57777.87095 17.56 0.02 2017-01-25 18:51:56 R 57778.79509 17.57 0.02 There is an SDSS galaxy J083450.96+611258.7 at the position of the source with r = 17.704 +/- 0.009 and R = 17.502 +/- 0.020 (Lupton 2005 transformation equations) which might be a host galaxy of the transient. The source is fading during our observations down to the level of the host galaxy within 2 sigma. This may be a supernova or a GRB afterglow.