//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20737 SUBJECT: LIGO/Virgo G275404: MASTER automatic follow up observations DATE: 17/02/25 19:30:18 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.M. Lipunov, E. Gorbovskoy, N.Tyurina, V.Shumkov, P.Balanutsa, V.G. O.Gress, Kornilov, A.Kuznetsov, M.I.Panchenko, A.V.Krylov, I.Gorbunov Lomonosov Moscow State University, Sternberg Astronomical Institute N.M. Budnev, O. Gress, K. Ivanov, S.Yazev Irkutsk State University V.Yurkov, Yu.Sergienko, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk R.Podesta, C.Lopez, F. Podesta Observatorio Astronomico Felix Aguilar (OAFA) , National University of San Juan, Argentina H. Levato, C. Saffe Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE), San Juan, Argentina 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 MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Tunka was started inspection of the the LIGO/Virgo G275404 50 sec after notice time and 1626 sec after trigger time at 2017-02-25 18:57:27 UT. The 5-sigma upper limit has been about 18.0 - 20.0 mag The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20738 SUBJECT: LIGO/Virgo G275404: Identification of a GW CBC Candidate DATE: 17/02/25 19:38:06 GMT FROM: Surabhi Sachdev at LIGO/Caltech The LIGO Scientific Collaboration and Virgo report: The pycbc CBC analysis (Usman et al. 2016, CQG 33, 215004) identified candidate G275404 during real-time processing of data from LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at 2017-02-25 18:30:21.374 UTC (GPS time:1172082639.374). G275404 is an event of interest because its false alarm rate, as determined by the online analysis, is 1.89e-07 Hz or about one in 2 months, passing our stated alert threshold of ~1/month. The event's properties can be found at this URL: https://gracedb.ligo.org/events/G275404 Based on preliminary matched-filter estimates of the masses and spins, if astrophysical, there is a 100% 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 90% chance that the system ejected enough neutron-rich material to power an electromagnetic transient. One sky map with directional 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 sections of an annulus. The 50% credible region spans about 460 deg2 and the 90% region about 2100 deg2. The luminosity distance is estimated to be 280 +/- 80 Mpc (mean +/- standard deviation). This is the preferred sky map at this time. Updates on our analysis of this event will be sent as they become available. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20739 SUBJECT: LIGO/Virgo G275404: IceCube neutrino observations DATE: 17/02/25 20:41:31 GMT FROM: Imre Bartos at Columbia/LIGO I. Bartos, S. Countryman (Columbia), C. Finley (U Stockholm), E. Blaufuss (U Maryland), R. Corley, Z. Marka, S. Marka (Columbia) on behalf of the IceCube Collaboration We searched IceCube online track-like neutrino candidates (GFU) detected in a [-500,500] second interval about the LIGO-Virgo trigger G275404. We compared the candidate source directions of 3 temporally-coincident neutrinos to the pyCBC skymap, with the following parameters: # dt[s] RA[deg] Dec[deg] E[TeV] Sigma[deg] -------------------------------------------- 1. -452.4 4.3 35.8 1.48 2.25 2. -162.3 274.0 77.0 0.60 0.19 (dt-time from GW; RA,Dec-sky location; E-reconstructed energy; Sigma-uncertainty of direction reconstruction) The analysis found NO COINCIDENT ONLINE TRACK-LIKE NEUTRINO CANDIDATES detected by IceCube within the 500 second window surrounding G275404 within the BAYESTAR skymap. In addition, we are performing coincident searches with other IceCube data streams, including the high-energy starting events (HESE) and Supernova triggers. HESE events have typical energies > 60 TeV and start inside the detector volume, leading to a relatively pure event sample with a high fraction of astrophysical neutrinos. The SN trigger system is sensitive to sudden increases in photomultiplier counts across the detector, which could indicate a burst of MeV neutrinos. We will submit separate GCN circulars if coincident HESE or SN triggers are found. The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. For a description of the IceCube realtime alert system, please refer to; for more information on joint neutrino and gravitational wave searches, please refer to. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20740 SUBJECT: LIGO/Virgo G275404: MASTER Tunka OT detection DATE: 17/02/25 20:43:18 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.M. Lipunov, E. Gorbovskoy, N.Tyurina, V.Shumkov, P.Balanutsa, V.G. O.Gress, Kornilov, A.Kuznetsov, M.I.Panchenko, A.V.Krylov, I.Gorbunov Lomonosov Moscow State University, Sternberg Astronomical Institute N.M. Budnev, O. Gress, K. Ivanov, S.Yazev Irkutsk State University V.Yurkov, Yu.Sergienko, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk R.Podesta, C.Lopez, F. Podesta Observatorio Astronomico Felix Aguilar (OAFA) , National University of San Juan, Argentina H. Levato, C. Saffe Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE), San Juan, Argentina 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 MASTER OT J173532.70+103810.5 - possble new CV or? MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 17h 35m 32.70s +10d 38m 10.5s on 2017-02-25.80727 UT. (see GCN 20738) The OT magnitude in 'C' filter is 15.4m (limit 16.0m). The OT is seen in 2 images. There is no minor planet at this place. We have reference image without OT on 2015-01-27.94672 UT with magnitude limit in 'C' filter 19.8m. Spectral observations are required. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20741 SUBJECT: LIGO/Virgo G275404: AGILE MCAL observations DATE: 17/02/25 21:53:11 GMT FROM: Francesco Verrecchia at ASDC, INAF-OAR A. Ursi (INAF/IAPS), M. Pilia (INAF/OA-Cagliari), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A. Bulgarelli, V. Fioretti, N. Parmiggiani (INAF/IASF-Bo), P. Munar-Adrover (INAF/IAPS), F. Verrecchia (ASDC and INAF/OAR), A. Zoli (INAF/IASF-Bo), C. Pittori, F. Lucarelli (ASDC and INAF/OAR), G. Piano, A. Argan (INAF/IAPS), M. Cardillo (INAF/OA-Arcetri and INAF/IAPS), Y. Evangelista, I. Donnarumma (INAF/IAPS), G. Minervini (INAF/IAPS), F. Fuschino, M. Marisaldi (INAF/IASF-Bo and Bergen University), A. Giuliani (INAF/IASF-Mi), 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 G275404 at T0 = 2017-02-25 18:30:21.374 UTC, a preliminary analysis of the AGILE-GW fast data processing procedure found no AGILE MiniCALorimeter (MCAL) event candidates within a time interval covering -/+ 40 sec from the LIGO T0. Two data acquisitions where collected about 45 sec before and 45 sec after the LIGO T0; they show no significant transient candidate event. A 3-sigma UL was computed for a 1 s integration time, on different celestial positions within the G275404 error box, and varies from a minimum of 5.3e-7 erg cm^-2 to a maximum of 10.3e-7 erg cm^-2, assuming as spectral model a single power law with photon index 1.4. The AGILE-MCAL instrument is a mini-calorimeter with a 4-PI FoV, working in the range 0.4 - 100 MeV. Additional analysis of AGILE GRID and Super-Agile data is in progress. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20742 SUBJECT: LIGO/Virgo G275404: Fermi GBM Observations DATE: 17/02/26 00:59:37 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 (USRA), 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 81% of the LIGO probability map for G275404 at the event time, with much of the northern high probability region and half of the southern arc observed. There is no GBM on-board trigger around the event time. The untargeted ground-based search of GBM data for short-duration GRBs (Briggs et al., in prep) found no candidates close in time to G275404. The targeted search of the GBM data ([1], [2]) also did not find a significant gamma-ray signal. This search processes time scales of 0.256 to 8.192 s within 30 s of the LIGO event. No interesting gamma-ray candidate was found within this time window. Any prompt gamma-ray burst emission, above the GBM detection threshold, must have been occulted by the Earth for Fermi. The Earth-occulted region is a circle with radius of 68 degrees, centered on RA, Dec = 134.5, +25.6. Further analysis and upper limits will be reported later. [1] L. Blackburn et al. 2015, ApjS 217, 8 [2] A. Goldstein et al. arXiv:1612.02395 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20743 SUBJECT: LIGO/Virgo G275404: AGILE-GRID preliminary analysis DATE: 17/02/26 01:06:17 GMT FROM: Francesco Verrecchia at ASDC, INAF-OAR M. Pilia (INAF/OA-Cagliari), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), P. Munar-Adrover, M. Cardillo (INAF/IAPS), F. Verrecchia (ASDC and INAF/OAR), A. Bulgarelli, V. Fioretti, A. Zoli , N. Parmiggiani (INAF/IASF-Bo), C. Pittori (ASDC and INAF/OAR), I. Donnarumma, G. Piano (INAF/IAPS), F.Lucarelli (ASDC and INAF/OAR), A. Giuliani (INAF/IASF-Mi), 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, G. Minervini (INAF/IAPS), A. Trois (INAF/OA-Cagliari), report on behalf of the AGILE Team: In response to the LIGO/Virgo GW trigger G275404 we performed an analysis of the AGILE Gamma-Ray Imaging Detector (GRID) data on different timescales. On LIGO trigger time (T0=2017-02-25 18:30:21.374 UT) the GRID exposure covered about 30% of the LIGO localization region (in the time interval T0-100s, T0+100s) that was observed with off-axis angles between 10 and 70 deg. An analysis of the data in the energy range 50 MeV - 10 GeV was performed on timescales from 2 to 100 sec centered at T0. Preliminary values of 3-sigma upper limits obtained within the accessible G275404 localization region are reported below: 1.8e-06 erg cm^-2 s^-1 for integration time of 2s, 1.5e-07 erg cm^-2 s^-1 for integration time of 20s, 3.5e-08 erg cm^-2 s^-1 for integration time of 100s. These ULs apply to a large fraction of the GRID-exposed LIGO localization region. We are currently analyzing the significance of a gamma-ray source candidate within that region. These measurements were obtained with AGILE observing a large portion of the sky in spinning mode. Additional analysis of AGILE data is in progress. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20745 SUBJECT: LIGO/Virgo G275404: SVOM/Mini-GWAC: Observations of initial skymap DATE: 17/02/26 03:01:37 GMT FROM: Chao Wu at NAOC J.Y. Wei (NAOC), X.H. Han (NAOC), X.M. Meng (NAOC), N. Leroy (LAL), S. Antier (LAL), C. WU (NAOC), L.P. Xin (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), D. Dornic (CPPM), B.B. Wu (IHEP), J.L. Atteia (IRAP), D. G?tz (CEA), C.Lachaud (APC), on behalf of the SVOM Gravitational Astronomy group report: We observed about 3200 square degree (8 sky regions) of the skymap of the advanced LIGO trigger G275404, with SVOM/Mini-GWAC, at Xinglong Observatory of NAOC equipped with U9000 camera (FOV~400 square degree/camera). SVOM/Mini-GWAC 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 46.6% prior probability that these 8 regions contain the true location of the source. The coordinates of the 8 regions and observation time are list following: start-obs(UTC) end-obs(UTC) Ra Dec Camera_ID 2017-02-25 19:23:51.9 2017-02-25 20:41:04.7 10:33:59.6 +30:12:22 C3 2017-02-25 19:23:51.9 2017-02-25 20:41:06.2 10:38:05.6 +10:07:57 C4 2017-02-25 19:23:42.2 2017-02-25 22:13:19.6 17:18:04.0 +69:28:00 C5 2017-02-25 19:23:44.7 2017-02-25 22:13:38.0 17:21:47.1 +50:28:32 C6 2017-02-25 13:01:04.2 2017-02-25 21:37:38.1 09:21:25.5 +69:40:01 C7 2017-02-25 13:01:04.2 2017-02-25 21:37:39.7 09:23:01.6 +50:00:25 C8 2017-02-25 21:39:38.3 2017-02-25 22:13:28.5 20:00:36.6 +69:38:42 C7 2017-02-25 21:39:38.3 2017-02-25 22:13:25.5 20:01:12.7 +50:00:21 C8 The first image (which is covered in our routine survey) was taken ~5 hours 29 minutes before the event trigger. No any significant transient is found in our online pipeline. The image analysis is ongoing in detailed processing with our offline pipeline. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20746 SUBJECT: LIGO/Virgo G275404: Swift/BAT data search DATE: 17/02/26 03:12:18 GMT FROM: Scott Barthelmy at NASA/GSFC T. Sakamoto (AGU), S.D. Barthelmy (NASA/GSFC), A. Y. Lien (GSFC/UMBC), D.M. Palmer (LANL), 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 G275404 (LIGO/VIRGO Collaboration GCN Circ. 20738), where T0 is the LIGO trigger time (2017-02-25T18:30:21.374023 UTC). The BAT pointing position at T0 is RA = 174.752 deg, DEC = -37.723 deg, ROLL = 153.273 deg. The BAT Field of View (>0.1 partial coding) covers 18.68% of the integrated LIGO localization probability. 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 ~ 7.3 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 81.32% 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: 20748 SUBJECT: LIGO/Virgo G275404: MASTER bright OT detection DATE: 17/02/26 08:01:03 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.M. Lipunov, T.Pogrosheva, E. Gorbovskoy, N.Tyurina, V.Shumkov, P.Balanutsa, V.G. O.Gress, Kornilov, A.Kuznetsov, 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 N.M. Budnev, O. Gress, K. Ivanov, S.Yazev Irkutsk State University V.Yurkov, Yu.Sergienko, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk R.Podesta, C.Lopez, F. Podesta Observatorio Astronomico Felix Aguilar (OAFA) , National University of San Juan, Argentina H. Levato, C. Saffe Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE), San Juan, Argentina 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 MASTER OT J105958.00-115756.5 - possble new CV ? MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 10h 59m 58.00s -11d 57m 56.5s on 2017-02-25.96032 UT during LIGO/Virgo G275404 (GCN 20738). The OT unfiltered magnitude is 17.1m (mlim = 20.0). The OT is seen in 2 images. There is no minor planet at this place. We have reference image on 2015-05-17.82159 UT with unfiltered mlim= 20.0m. There is GALEX-DR5 source in half pixel offset. Spectral observations are required. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20750 SUBJECT: LIGO/Virgo G275404: Follow-up of MASTER OT J173532.70+103810.5 DATE: 17/02/26 13:38:09 GMT FROM: Chris Copperwheat at LJMU ArI From C.M. Copperwheat (LJMU), A.S. Piascik (LJMU) and I.A. Steele (LJMU) on behalf of a larger collaboration. We attempted to observe the transient MASTER OT J173532.70+103810.5 reported in GCN #20740, using the SPRAT spectrograph on the Liverpool Telescope, on 2017-02-26 at 05:19 UT. We do not detect a transient at the reported coordinates. We estimate the limiting (unfiltered) magnitude of our acquisition frame to be ~19.5. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20751 SUBJECT: LIGO/Virgo G275404 ANTARES search DATE: 17/02/26 14:13:51 GMT FROM: Damien Dornic at CPPM/CNRS M. Ageron (CPPM/CNRS), B. Baret (APC/CNRS), A. Coleiro (IFIC & APC), 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 G275404 event using the initial LIGO skyprobcc_cWB probability map at event time (LVC GCN Circ. 20738). 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/G275404.png (gwantares/ANT@GW). Considering the location probability provided by the LIGO collaboration, there is a 45% chance that the GW emitter was in the ANTARES field of view. No up-going muon neutrino candidate events were recorded within the 90% contour during a +/- 500s time-window centered on the G275404 event time. The expected number of atmospheric background events in the region visible by ANTARES is ~1.3e-3 in the +/- 500s time window. An extended search during +/- 1 hour gives no up-going neutrino coincidence. An estimate of the upper limit on the associated neutrino fluence will be sent in a subsequent circular. 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: 20752 SUBJECT: LIGO/Virgo G275404: Swift-XRT sources DATE: 17/02/26 14:39:49 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), 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 83 observations of galaxies (from the 2MPZ catalogue) within the LVC error region for the GW trigger G275404, using the 'bayestar' GW localisation map. As this is a 3D skymap, galaxy distances were taken into account in selecting which ones to observe. The observations currently span from 17 ks to 42 ks after the LVC trigger, and cover 9.9 sq degrees on the sky (corrected for overlaps). This covers 0.014 of the probability in the LVC skymap, and 0.028 of the probability in the LVC map after convolving with the 2MPZ galaxy catalogue, as described by Evans et al., (2016, MNRAS, 462, 1591). No new X-ray sources have been detected. This circular is an official product of the Swift team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20753 SUBJECT: LIGO/Virgo G275404: NOT Follow-up of MASTER OT DATE: 17/02/26 15:44:25 GMT FROM: Mansi M. Kasliwal at Caltech C. Fremling (OKC), F. Taddia (OKC), R. Amanullah (OKC), J. Sollerman (OKC), M. M. Kasliwal (Caltech) report on behalf of the iPTF and GROWTH collaborations We observed the transient MASTER OT J173532.70+103810.5 reported in LVC GCN #20740, using ALFOSC on the Nordic Optical Telescope, on 2017-02-26 at 05:40 UT. We do not detect any transient at the reported coordinates, in agreement with observations from the Liverpool Telescope (LVC GCN # 20750). The 3-sigma limiting (unfiltered) magnitude of our stacked acquisition frames at the expected position of the transient is ~21.1 mag. This would imply an extremely fast rate of fading > approx. 10 mag / day! We caution that there is a variable star (PTF1717w) which is within a few arcsec of the reported MASTER OT position. But this nearby variable star only shows variations between roughly 19.0-19.6 mag in R-band in archival PTF data. Additional follow-up is encouraged. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20754 SUBJECT: LIGO/Virgo G275404: AGILE-GRID detection of a possible gamma-ray transient DATE: 17/02/26 16:26:01 GMT FROM: Francesco Verrecchia at ASDC, INAF-OAR M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A. Giuliani (INAF/IASF-Mi), A. Bulgarelli (INAF/IASF-Bo), F. Verrecchia (ASDC and INAF/OAR), P. Munar-Adrover, M. Cardillo (INAF/IAPS), V. Fioretti, A. Zoli , N. Parmiggiani (INAF/IASF-Bo), M. Pilia (INAF/OA-Cagliari), C. Pittori (ASDC and INAF/OAR), I. Donnarumma, G. Piano (INAF/IAPS), F. Lucarelli (ASDC and INAF/OAR), 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, G. Minervini (INAF/IAPS), A. Trois (INAF/OA-Cagliari), report on behalf of the AGILE Team: Following up on the analysis of AGILE-GRID data in response to the LIGO/Virgo GW event G275404, we performed an improved search for transient gamma-ray emission within the G275404 localization region. The AGILE-GRID had significant exposure of a good fraction of the G275404 localization region before and after the LIGO trigger time (T0=2017-02-2518:30:21.374 UT). Additional analysis in the energy range 30 MeV-50 GeV reveals the existence of a 3.6-sigma gamma-ray transient event during the interval - 20 / + 10 sec from T0, at the position with centroid coordinates: R.A.= 288.43 deg, DEC= 10.72 deg (Galactic l = 45.0, b = 0.0), and error radius R = 4 deg (stat. 68% confidence) + 1 deg (syst.). We name this transient AGL J1914+1043. Despite its weakness, we consider AGL J1914+1043 an interesting source candidate for its timing properties and position within the G275404 localization region. No MCAL trigger event was recorded on board in coincidence with AGL J1914+1043 which appears to be detected only at energies above 70 MeV. This measurement was obtained with AGILE observing a large portion of the sky in spinning mode. Additional analysis of AGILE data is in progress. Multifrequency observations of the AGL J1914+1043 field are encouraged. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20755 SUBJECT: LIGO/Virgo G275404: INTEGRAL search for a prompt gamma-ray counterpart DATE: 17/02/26 17:19:13 GMT FROM: Volodymyr Savchenko at APC,Paris V. Savchenko (ISDC, University of Geneva, CH) on behalf of the INTEGRAL group: S. Mereghetti (IASF-Milano, Italy), C. Ferrigno ((ISDC, University of Geneva, CH), 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, Saclay/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 burst candidate G275404. The satellite was pointing at RA=17:44:43 Dec=-25:57:27 (in the direction of the Galactic Center region), close to the low-probability area of LIGO localization. About 2% of the probability was contained in the field of view of INTEGRAL IBIS and SPI. Depending on the location within the LIGO 90% localization region, as well as the assumed counterpart spectrum and duration, the best upper limit is set by the anti-coincidence shield of the spectrometer on board of INTEGRAL (SPI/ACS), the anti-coincidence shield of the IBIS instrument (IBIS/Veto), or by the imaging coded mask instruments (IBIS and SPI). The combination of these instruments covered the full LIGO 90% confidence region and provided stringent constraints on the flux of a possible electromagnetic counterpart in the energy range covered by the INTEGRAL instruments. The INTEGRAL Burst Alert System (IBAS) did not identify any unusual transients in coincidence with the LIGO/Virgo trigger. The IBAS inspects both ISGRI Field of View and all-sky SPI-ACS light curve. The IBAS trigger closest in time to the GW candidate ("Weak" ISGRI trigger 7706) happened at UTC 2017-02-25 11:32:15.56 and it's location (RA=270.48, Dec=-25.08, 3.73 arcmin radius 68% containment, statistical uncertainty only) was outside the 90% probability containment of the LIGO localization region. The nearest excess over the background rate identified by SPI-ACS offline pipeline happened 453 seconds after the LIGO/Virgo trigger. It has an SNR of 5.5, duration of 100 ms, and is compatible with cosmic ray origin. We investigated the SPI-ACS, IBIS/Veto, and IBIS/ISGRI light curves between -500 and +500 s from the trigger time (2017-02-25 18:30:21.3 UTC) on temporal scales from 0.1 to 100 s, and found no evidence for any deviation from the background. We estimate combined typical 3-sigma upper limits of 4.3e-7 erg/cm2 (75-2000 keV) for 8s duration assuming Band model parameters alpha=-1, beta=-2.5, and E_ peak = 300 keV. To derive a limit for a typical short burst with 1 s duration, we use a harder cutoff power law spectrum with a slope of -0.5 and an Epeak = 500 keV: we find a limiting fluence of 1.5e-7 erg/cm2 (75-2000 keV) at 3 sigma c.l. These limits assume a perpendicular direction of the burst to the INTEGRAL pointing direction, optimal for SPI-ACS sensitivity. However the extent of the region with optimal response depends on the possible source spectrum: we perform a detailed calculation only for a cutoff powerlaw spectrum with a slope of -0.5 and an Epeak = 500 keV: we estimate that 30% of the LIGO localization probability region is covered with a range of sensitivity from optimal for SPI-ACS (mentioned above) to 50% worse. About 2% of the LIGO localization in the field of view of IBIS and SPI is covered with at least factor 2 better sensitivity. 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 substantially as a function of the source incident angle with an optimal effective area of about 6000 cm2 at 1 MeV. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20756 SUBJECT: LIGO/Virgo G275404: Fermi-LAT search for a high-energy gamma-ray counterpart DATE: 17/02/26 18:56:25 GMT FROM: Judith Racusin at NASA/GSFC D. Kocevski (NASA/MSFC), N. Omodei (Stanford), G. Vianello (Stanford), J. L. Racusin (NASA/GSFC), S. Buson (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 G275404. Fermi-LAT had an instantaneous coverage of ~10% at the time of the trigger (T0 = 2017-02-25 18:30:21.374 UTC), and reached 100% cumulative coverage within ~8 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 map in the time window from T0 to T0 + 10 ks, and no significant new sources are found. We also performed a search which adapted the time interval of the analysis to the exposure of each region of the sky. No significant candidate counterpart was found. The position of the AGILE candidate counterpart (Tavani et al., GCN 20754) was outside of the LAT field of view at the time of the LIGO event until T0+3.5 ks. Searching over an interval from T0+3.5 to T0+6.7 ks, we do not find any significant excess at the AGILE position, placing an upper limit in the 100 MeV - 100 GeV band of 3e-10 erg/cm2/s. Using LAT Low Energy (LLE) data (Pelassa et al 2010), we perform a counting analysis at energies >30 MeV. LLE is a loose event selection allowing for larger incident angles and lower energies with respect the standard LAT likelihood analysis. We searched for excesses coincident with the AGILE candidate at the time of the LIGO trigger, 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: 20757 SUBJECT: LIGO/Virgo G275404: Keck spectrum of MASTER OT J105958.00-115756.5 DATE: 17/02/26 19:08:17 GMT FROM: Igor Andreoni at Swinburne U of Tech J. Cooke, I. Andreoni, U. Mestric (Swinburne Univ.), T. Moriya (NAOJ) A spectrum of the MASTER transient OT J105958.00-115756.5 (GCN Circ. 20748) was taken with the Keck telescope on 2017-02-26.54 UT during the follow up of the LIGO event G275404 (LIGO/VIRGO Collaboration GCN Circ. 20738). The observations were performed with the Low Resolution Imaging Spectrometer for a total exposure time of 2300s under several magnitudes of variable cloud extinction. The preliminary analysis reveals a blue and mostly featureless spectrum at redshift z=0.0017. The spectrum shows evidence of Balmer series lines in absorption, with a potential weak emission in the H-gamma trough. This result is not inconsistent with Lipunov et al. (GCN Circ. 20748), who suggest the event to be a CV. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20758 SUBJECT: LIGO/Virgo G275404: MASTER OT is outside LIGO error region DATE: 17/02/26 20:45:35 GMT FROM: Mansi M. Kasliwal at Caltech J. Sollerman (OKC), S. Smartt (QUB) and M. M. Kasliwal (Caltech) report The position of MASTER OT J173532.70+103810.5 (LVC GCN #20740) is outside the LIGO 90% localization contour. Further follow-up of the possibly fast fading nature of the source may not be necessary in the GW context. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20759 SUBJECT: LIGO/Virgo G275404: MASTER PSN detection from the maximal probability LIGO region DATE: 17/02/27 09:25:22 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.M. Lipunov, E. Gorbovskoy, P.Balanutsa, E. Gorbovskoy, N.Tyurina, V.Shumkov, O.Gress, V.G. Kornilov, A.Kuznetsov, M.I.Panchenko, A.V.Krylov, I.Gorbunov, T.Pogrosheva Lomonosov Moscow State University, Sternberg Astronomical Institute R. Rebolo, M. Serra-Ricart, G. Israelian, N.Lodiu The Instituto de Astrofisica de Canarias D.Buckley, S. Potter, M. Kotze, South African Astronomical Observatory N.M. Budnev, O. Gress, K. Ivanov, S.Yazev Irkutsk State University V.Yurkov, Yu.Sergienko, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk R.Podesta, C.Lopez, F. Podesta Observatorio Astronomico Felix Aguilar (OAFA) , National University of San Juan, Argentina H. Levato, C. Saffe Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE), San Juan, Argentina A. Tlatov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory MASTER-IAC auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 19h 50m 04.70s +52d 38m 56.2s on 2017-02-26.26975 UT during inspection of G275404. The OT unfiltered magnitude is ~ 19.0m (m_limit=19.5m). This PSN is in 2.4W,2.6N of disc galaxy PGC2420186 (http://leda.univ-lyon1.fr/ledacat.cgi?PGC2420186 ) This PSN is seen in 3 images. There is no minor planet at this place. We have reference image without OT on 2016-05-07.15047 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/195004.84523853.6.png Spectral observations are required. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20760 SUBJECT: LIGO/Virgo G275404: REM optical/NIR observations DATE: 17/02/27 11:33:14 GMT FROM: Andrea Melandri at INAF-OAB A. Melandri, P. D'Avanzo (INAF-OAB), G. Greco (Urbino University/INFN Firenze), D. Fugazza, S. Covino, (INAF-OAB), E. Palazzi (INAF-IASF Bo), M. Branchesi (Urbino University/INFN Firenze), L. Amati (INAF-IASF Bo), L. A. Antonelli, (INAF-OAR), S. Ascenzi (INAF-OAR), M.T. Botticella (INAF-OAC), S. Campana (INAF-OAB), E. Cappellaro (INAF-OAPD), V. D'Elia (INAF-ASDC), 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), 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 (GRAWITA) report: We carried out optical/NIR follow-up observations of the LIGO/Virgo GW trigger G275404 (LVC GCN Circ. 20738) with the 60-cm robotic telescope REM located at the La Silla Observatory (Chile). The observations were carried out on 2017 Feb 26 from 00:15:16 UT to 04:52:42 UT (from 5.75 to 10.37 hours after T0, LVC GCN Circ. 20738), simultaneously in the g, r, i, z and H bands. We observed the twenty brightest (according to the B magnitude reported in the GLADE catalogue) galaxies within the bayestar probability sky map visible from La Silla. The galaxies with a catalogued distance in the range 200-360 Mpc (evaluated on the basis of directional distance information, Singer et al. 2016, ApJL 829, 15) and brighter than Mag(B)=15.4 were selected within the 60% containment probability contour of the sky map using the GWsky script (https://github.com/ggreco77/GWsky). RA(J2000) Dec(J2000) Dist(Mpc) Mag(B) --------------------------------------- 166.78835 -18.02376 309.030 14.37 169.72995 -20.43487 275.423 14.83 160.82343 -12.36031 235.505 14.97 164.62923 -15.38000 292.415 15.04 159.06644 -12.72557 229.087 15.07 157.75930 -10.56777 276.694 15.13 165.18204 -19.41204 255.859 15.18 182.20964 -31.44722 204.174 15.21 159.31235 -11.35495 231.560 15.23 168.87087 -20.79923 279.087 15.26 169.93326 -21.97061 354.813 15.29 174.77983 -27.54560 275.423 15.31 160.25761 -11.44282 235.303 15.31 166.36340 -21.09875 280.543 15.35 160.15845 -14.25566 231.206 15.37 166.13525 -18.84047 292.415 15.38 172.93570 -25.07778 280.543 15.38 156.54243 -07.94825 285.508 15.38 173.67679 -24.94764 221.690 15.39 169.13541 -20.90190 297.852 15.40 A preliminary analysis reveals no obvious optical/NIR candidate counterpart in the above galaxies down to the following magnitudes: r > 19.5, H > 17.0 (AB, 3sigma upper limit, calibrated against the APASS and 2MASS catalogues, respectively). Further analysis is in progress. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20762 SUBJECT: LIGO/Virgo G275404: Keck LRIS classification of MASTER PSN candidate DATE: 17/02/27 18:59:08 GMT FROM: Mansi M. Kasliwal at Caltech N. Blagorodnova (Caltech), A. Ho (Caltech), T. Hung (UMd), K. Vyhmeister (Caltech), S. R. Kulkarni (Caltech), D. Cook (Caltech), A. van Sistine (UW Milwaukee) and M. M. Kasliwal (Caltech) report on behalf of the iPTF and GROWTH collaborations We observed the transient MASTER PSN reported in LVC GCN #20759, using LRIS on the Keck I Telescope, on 2017-02-26 at 05:45 UT. The spectrum shows relatively broad features at z=0.017. A SNID fit is consistent with a Type Ic (possibly Ic broad-line) a month after maximum light. The host galaxy, which does not have a previously known spectroscopic redshift, is also a line emitter in the CLU (Census of the Local Universe; Cook et al. 2017) narrow-band redshifted Halpha imaging, consistent with being local. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20766 SUBJECT: LIGO/Virgo G275404: AstroSat CZTI upper limits DATE: 17/02/27 20:44:35 GMT FROM: Varun Bhalerao at Indian Inst of Tech Sujay Mate (IUCAA), Varun Bhalerao (IIT Bombay), 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: We carried out offline analysis of data from AstroSat CZTI in a 100 second window centred on the G275404 trigger time, UT 2017-02-25 18:30:21.374, to look for any coincident hard X-ray flash. CZTI is a coded aperture mask instrument that has considerable effective area for about 29% of the entire sky. Based on the pointing direction of AstroSat at the time of the GW event and the baystar skymap provided by LVC (baystar.fits.gz), the sky visible to CZTI has 22.1% probability of containing the EM counterpart. CZTI data were de-trended to remove orbit-wise background variation. We then searched data from the four independent, identical quadrants to look for coincident spikes in the count rates. Searches were undertaken by binning the data in 0.1s, 1s and 10s respectively. Statistical fluctuations in count rates were estimated by using data from 10 neighbouring orbits. We selected confidence levels such that the probability of a false trigger in this 100s window is 10^-4. We do not find any evidence for any hard X-ray transient in this window. We model the source with a band function using standard parameters, with alpha = -1, beta = -2.5 and E_peak = 300 keV. The sensitivity of CZTI varies with direction. We weight the sensitivity by the baystar probability density map to calculate upper limits on any coincident emission from the source. In the 30-200 keV, the upper limits for source fluence are 1.6e-07 ergs/cm^2, 3.9e-07 ergs/cm^2 and 9.0e-07 ergs/cm^2 for search timescales of 0.1, 1, and 10 seconds respectively. The corresponding flux upper limits for the three timescales are 1.6e-06, 3.9e-07, and 9.0e-08 ergs/cm^2/sec respectively. Plots showing CZTI sensitivity as a function of direction for this event can be found at https://gracedb.ligo.org/apiweb/events/G275404/files/G275404_CZTI_limits.pdf,0 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20771 SUBJECT: LIGO/Virgo G275404: MASTER bright PSN detected on 27 Feb from the maximum of probability of LIGO localization DATE: 17/02/28 01:09:30 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.M. Lipunov, P.Balanutsa, E. Gorbovskoy, T.Pogrosheva, N.Tyurina, A.Kuznetsov, O.Gress, V.Shumkov, V.Kornilov, D.Vlasenko, M.I.Panchenko, A.V.Krylov, I.Gorbunov, Lomonosov Moscow State University, Sternberg Astronomical Institute R. Rebolo, M. Serra-Ricart, G. Israelian, N.Lodiu, The Instituto de Astrofisica de Canarias D.Buckley, South African Astronomical Observatory N.M. Budnev, O. Gress, K. Ivanov, S.Yazev, Irkutsk State University R.Podesta, C.Lopez, F. Podesta, Observatorio Astronomico Felix Aguilar (OAFA) , National University of San Juan, Argentina H. Levato, C. Saffe, Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE), San Juan, Argentina A. Tlatov, V.Sennik, Kislovodsk Solar Station of the Pulkovo Observatory V.Yurkov, Yu.Sergienko, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk MASTER OT J192402.43+421720.0 - bright PSN in PGC2195963 MASTER-IAC auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 19h 24m 02.43s +42d 17m 20.0s on 2017-02-27 03:59:05.256UT during LIGO G275404 inspection (2017-02-25 18:30:51 UTC event time). The OT unfiltered magnitude is ~16.6m (mlim=18.4). The OT is seen in 5 image. There is no minor planet at this place. There is PGC2195963 disc galaxy in 12.3" of this PSN ( http://leda.univ-lyon1.fr/ledacat.cgi?o=PGC2195963 ) We have reference image on 2016-03-19 05:07:19UT with unfiltered mlim=19.8. Spectral observations are required. The discovery and reference images are http://master.sai.msu.ru/static/OT/MASTEROTJ192402.43+421720.0.png The position of MASTER OT J173532.70+103810.5 (Lipunov et al. GCN #20740, Sollerman et al. GRC #20758) is inside G274296 (2017-02-17) LIGO localization (Shawhan et al. GCN #20689 ) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20774 SUBJECT: LIGO/Virgo G275404: CNEOST optical observations DATE: 17/02/28 14:58:21 GMT FROM: Jinzhong Liu at Xinjiang Astronomical Observatory B. Li (PMO/CAS), D. Xu (NAO/CAS), H.B. Zhao, G.T. Zhaori, H. Lu, R.Q. Hong, L.F. Hu (PMO/CAS), T.M. Zhang, X. Zhou, H.X. Feng, Z.P. Zhu (NAO/CAS), J.Z. Liu, H.B. Niu, Y. Zhang, X. Zhang, G.X. Pu, S.G. Ma,T.Z. Yang, F.F. Song (XAO/CAS), J. Mao, J.M. Bai (YNAO/CAS) report on behalf of the Gravitational Wave Follow-Up Network by NAO-PMO-XAO-YNAO in China (GWFUNC): We have performed tiled observations of LIGO/Virgo G275404 (LVC, GCN 20738) using the 1-m Chinese Near Earth Object Survey Telescope (CNEOST) at Xuyi, Jiangsu, China. CNEOST has a FOV of 3.0x3.0 deg^2, and carried out observations during 10:44:55.9 - 14:44:22.4 UT and 19:46:14.6 - 21:47:47.6 UT on 2017-02-26 in the Sloan r-filter. The skymap coverage is at https://dl.dropboxusercontent.com/u/3665676/G275404/skymap20170226NEOST.pdf and the typical limiting magnitude is of m(r)~20.0 mag. Preliminary analysis doesn't reveal optical transient brighter than m(r)~17.5 mag that is positionally coincident with SDSS host galaxy whose spectroscopic or photometric redshifts is < 0.1. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20778 SUBJECT: LIGO/Virgo G275404: Nearby Galaxies in the Localization Region DATE: 17/02/28 23:37:18 GMT FROM: Mansi M. Kasliwal at Caltech David O. Cook (Caltech), Angela Van Sistine (UW Milwaukee) and M. M. Kasliwal (Caltech) report on behalf of the iPTF and GROWTH collaborations We spatially cross-matched the LIGO/Virgo G275404 trigger (90% containment; LVC GCN 20738) with our Census of the Local Universe (CLU; Cook et al. in prep) galaxy catalog and found 8700 galaxies. This catalog is a compilation of galaxies with existing spectroscopic redshifts from many sources (e.g., NED, SDSS, etc) and new galaxies from a 3PI four-filter narrow-band survey to look for redshifted Halpha emission out to 200 Mpc with the Palomar 48-inch telescope. Currently, the narrow-band survey is only calibrated inside the footprint of SDSS. Of the 8700 galaxies in the error region, 7792 come from a compilation of known galaxies and 908 are new, emission-line galaxy candidates. We list here the top 20 galaxies sorted by star formation rate (SFR) independent of distance. These SFRs are derived from GALEX all sky kron FUV magnitudes via the prescription of Murphy et al. (2011) and have been corrected for internal dust extinction using a combination of GALEX FUV and 22um ALLWISE fluxes (Hao et al. 2011). The quoted stellar masses are derived from 3.4um ALLWISE fluxes and a mass-to-light ratio of 0.5 (McGaugh & Schombert et al. 2015). Name, RA (J2000), DEC (J2000), Distance (Mpc), log(SFR_FUV in Msun/yr), log(Mstar in Msun) ------------------------------------------------------------ ------------------------------ PGC45371, 196.60885, -40.41467, 64.3, 1.56, 11.41 PGC34266, 168.67487, -23.72769, 50.0, 1.50, 10.56 PGC27353, 144.20834, 11.75102, 123.1, 1.45, 10.58 VV 637, 150.86235, -1.54665, 197.5, 1.40, 10.69 UGC 05304 NED02, 148.293, 7.87353, 174.3, 1.33, 10.37 SDSS J094914.91+132616.9, 147.312, 13.438, 173.9, 1.33, 9.99 PGC62504, 282.907292, 23.6348261, 62.5, 1.32, 10.38 PGC45247, 196.28554, -32.19128, 135.4, 1.32, 10.90 PGC35241, 171.84762, -29.25758, 102.3, 1.30, 10.65 PGC28191, 147.17049, 9.00879, 127.9, 1.29, 10.69 MCG-01-27-027, 159.14729, -7.11283, 117.3, 1.28, 10.76 PGC63696, 297.24833, 50.3130183, 106.5, 1.27, 10.91 PGC29225, 151.15092, -1.74539, 195.5, 1.27, 10.57 PGC28271, 147.46491, 10.43199, 126.4, 1.27, 10.53 PGC30127, 154.7378, 1.66004, 196.6, 1.25, 10.71 PGC1195530, 151.70616, 1.4573, 198.7, 1.25, 10.64 PGC2672630, 300.72775, 64.89389, 189.4, 1.18, 10.93 PGC82908, 155.9038, -4.85393, 166.6, 1.16, 10.79 PGC28240, 147.34549, 1.14542, 107.1, 1.15, 10.86 CLU J20115561+6028326, 302.981, 60.4759, 176(+/-30), 1.13, 10.64 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20779 SUBJECT: LIGO/Virgo G275404: Nearby galaxy observations by J-GEM collaboration DATE: 17/03/01 05:57:38 GMT FROM: Michitoshi Yoshida at J-GEM Yoshida, M., Utsumi, Y. (Hiroshima U.), Itoh, R., Tachibana, Y., Fujiwara, T., Morita, K., Saito, Y., Kawai, N. (Tokyo Tech), Yanagisawa, K., Kuroda, D. (OAO, NAOJ) on behalf of J-GEM collaboration We conducted optical imaging observations of nearby galaxies within the probability skymap of G275404 (LVC; GCN 20738) with the 50cm MITSuME telescopes at Akeno Observatory and Okayama Astrophysical Observatoty (OAO) and the 91cm wide field near-infrared camera (OAOWFC) at OAO in the framework of J-GEM collaboration. We obtained optical three color data, g', Rc, and Ic, with MITSuME. Near-infrared J-band data were obtained with OAOWFC. The 5-sigma limiting AB magnitudes are listed below. No optical/infrared transient source corresponding to the GW event was found by these observations. Telescope: Akeno-MITSuME --------------------------------------------------------------- galaxy RA DEC UT g' Rc Ic --------------------------------------------------------------- GL070934+815806 107.392 81.9682 2017/2/26-10:57 17.2 16.3 16.2 GL082903+631748 127.2626 63.2968 2017/2/26-13:01 18.5 17.8 17.1 GL080157+755626 120.4879 75.9405 2017/2/26-12:32 17.5 16.7 16.4 GL205542+694433 313.9234 69.7426 2017/2/26-09:55 16.3 15.1 14.7 --------------------------------------------------------------- Telescope: OAO-MITSuME --------------------------------------------------------------- galaxy RA DEC UT g' Rc Ic --------------------------------------------------------------- GL080414+625854 121.0578 62.9817 2017/2/26-12:29 19.2 19.0 18.7 GL073200+834257 113 83.7157 2017/2/26-16:24 18.7 18.8 18.2 GL073048+734223 112.702 73.7063 2017/2/26-16:04 19.1 18.7 17.7 GL080012+681439 120.0508 68.2442 2017/2/26-15:04 19.1 18.9 18.6 GL080925+675304 122.3541 67.8845 2017/2/26-14:44 19.1 18.9 18.5 GL081102+674602 122.7601 67.7671 2017/2/26-14:24 19.2 19.1 18.7 GL101338-005532 153.4096 -0.9255 2017/2/26-14:01 18.3 18.4 17.8 GL080408+625902 121.0333 62.9839 2017/2/26-12:29 19.2 19.0 18.7 GL072924+720740 112.3508 72.1279 2017/2/26-12:08 18.5 18.4 18.1 GL072301+770105 110.7546 77.018 2017/2/27-16:34 19.6 19.1 18.2 GL081343+642011 123.4296 64.3365 2017/2/27-16:14 19.6 19.3 18.8 GL082406+672912 126.023 67.4866 2017/2/27-15:55 19.4 19.3 18.7 GL042619+861143 66.5777 86.1953 2017/2/27-15:11 19.3 19.1 18.5 GL053258+834643 83.2431 83.7786 2017/2/27-14:51 19.2 19.2 18.7 GL054237+832440 85.6532 83.411 2017/2/27-14:31 19.2 19.3 18.7 GL064623+750738 101.5974 75.1273 2017/2/27-14:12 19.4 19.2 18.7 --------------------------------------------------------------- Telescooe: OAOWFC ------------------------------------------------------ galaxy RA DEC UT J ------------------------------------------------------ GL072256+782247 110.7315 78.3796 2017/2/27-15:46 18.8 GL081343+642011 123.4296 64.3365 2017/2/27-15:20 18.0 GL072301+770105 110.7546 77.018 2017/2/27-14:54 18.8 GL080925+675304 122.3541 67.8845 2017/2/27-14:08 18.8 GL081102+674602 122.7601 67.7671 2017/2/27-14:08 18.8 GL080414+625854 121.0578 62.9817 2017/2/27-13:23 18.9 GL064623+750738 101.5974 75.1273 2017/2/27-12:37 18.8 GL080925+675304 122.3541 67.8845 2017/2/27-11:51 18.7 GL081102+674602 122.7601 67.7671 2017/2/27-11:51 18.7 ------------------------------------------------------ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20784 SUBJECT: LIGO/Virgo G275404: A near-infrared transient in the error circle of AGL J1914+1043 DATE: 17/03/01 09:17:28 GMT FROM: Michitoshi Yoshida at J-GEM Yoshida, M., Utsumi, Y., Nakaoka, T., Abe, T., Nagashima, H., Kawabata, K. S., Kawabata, M., Shiki, K. (Hiroshima U.), Ohsawa, R. and Sako, S. (U. of Tokyo) on behalf of J-GEM collaboration We performed near-infared H-band observations of nearby galaxies in the error circle of the gamma-ray transient candidate found in the AGILE-GRID data, AGL J1914+1043 (Tavani et al. GCN 20754), which is located at the edge of the skymap of G275404 (GCN 20738) with 1.5m Kanata telescope on UT 2017-02-27. The instrument used was an optical near-infrared simultaneous camera HONIR. We found a bright near-infrared transient in the observed field of GL191032+075314. The data was taken at 20:32UT on 2017-02-27. The H-band AB magnitude of the source was 16.3 +- 0.02. The location of the source is RA=19:10:31.46, DEC=+07:53:52.0 . We also conducted an I-band observation for this area simultaneously. No transient source was detected with the 5-sigma I-band limiting magnitude of 19.6. There is no bright counterpart in 2MASS H-band data, but a point source (SSTGLMC G042.1312-00.6118; in GLIMPSE I Spring '07 Catalog) is clearly seen at the same position in 3.6 um data taken by Spitzer GLIMPSE survey. The observation log with 5-sigma limiting magnitudes is shown below. Telescope: Kanata 1.5m telescope ------------------------------------------------------ galaxy RA DEC UT H ------------------------------------------------------ GL191032+075314 287.6351 7.8871 2017/2/27-20:32 18.7 GL192215+140356 290.561 14.0655 2017/2/27-21:11 17.5 GL191327+105427 288.3622 10.9076 2017/2/27-20:52 18.5 GL191032+075314 287.6351 7.8871 2017/2/27-20:32 18.3 GL190530+100857 286.3748 10.1491 2017/2/27-20:12 18.1 GL190618+125620 286.5759 12.9388 2017/2/27-19:53 18.2 GL190415+125637 286.0637 12.9437 2017/2/27-19:33 17.8 GL185836+113738 284.6512 11.6271 2017/2/27-19:13 17.9 ------------------------------------------------------ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20789 SUBJECT: LIGO/Virgo G275404: Fermi GBM Upper Limits DATE: 17/03/01 23:01:48 GMT FROM: Adam Goldstein at Fermi/GBM Adam Goldstein (USRA) and Colleen Wilson-Hodge (NASA/MSFC) report on behalf of the GBM-LIGO Group: Lindy Blackburn (CfA), Michael S. Briggs (UAH), Jacob Broida (Carleton College), Eric Burns (UAH), Jordan Camp (NASA/GSFC), Tito Dal Canton (NASA/GSFC), Nelson Christensen (Carleton College), Valerie Connaughton (USRA), 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) Fermi GBM observed 77% of the LALInference sky map at the time of the LIGO trigger, and we set the following flux upper limits for the entire visible sky map (excluded region is a circle with radius of 68 degrees centered on RA, Dec = 134.5, +25.6). Using a hard Band function with (Epeak, alpha, beta) = (500 keV, -0.5, -2.5), we set a 3 sigma, 1-second-averaged flux upper limit for any transient within 30 s of the LIGO trigger time in the 10-1000 keV band ranging from 5.0e-7 to 1.4e-6 erg/s-cm^2. Using an exponentially cutoff power law parametrized with (Epeak, index) = (566 keV, -0.42), which represents the average GBM-triggered short GRB, the upper limit ranges from 5.4e-7 to 1.4e-6 erg/s-cm^2. The upper limit in the region of the AGILE-GRID candidate, AGL J1914+1043 (Tavani et al., GCN 20754), is 5.0e-7 erg/s-cm^2 using the hard Band function and 5.4e-7 erg/s-cm^2 using the cutoff power law. Using the Earth Occultation technique (Wilson-Hodge et al. 2012, ApJS, 201, 33) to estimate the amount of persistent emission during a 48-hour period centered on the LIGO trigger time, we place the following range of 3-sigma day-averaged flux upper limits based on observed sources over the entire LIGO sky map: Energy min max median -------------------------------- 12- 27 keV: 0.08 0.62 0.12 Crab 27- 50 keV: 0.14 0.87 0.21 Crab 50-100 keV: 0.20 1.27 0.29 Crab 100-300 keV: 0.39 2.72 0.57 Crab 300-500 keV: 3.75 28.1 5.58 Crab These limits are based on the minimum requirement that each source in the Earth Occultation catalog was Earth-occulted at least 6 times in each of the 24 hour periods preceding and following the LIGO trigger and that the occultations were well separated from nearby bright sources. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20790 SUBJECT: LIGO/Virgo G275404: iPTF Optical Transient Candidates DATE: 17/03/02 07:29:15 GMT FROM: Mansi M. Kasliwal at Caltech M. M. Kasliwal (Caltech), S. M. Adams (Caltech), C. Cannella (Caltech), R. Lunnan (Caltech), R. Ferretti (OKC), T. Kupfer (Caltech), L. P. Singer (NASA/GSFC), S. B. Cenko (NASA/GSFC), R. Walters (Caltech), T. Barlow (Caltech), J. Rana (IUCAA), V. Bhalerao (IIT-B), A. A. Miller (Northwestern/Adler), Y. Cao (UW), R. Laher (IPAC), F. Masci (IPAC) report on behalf of the iPTF (intermediate Palomar Transient Factory) and GROWTH (Global Relay of Observatories Watching Transients Happen) collaborations: We performed tiled observations of LIGO/Virgo G275404 (LVC, GCN 20738) and LIGO/Virgo G275697 (LVC, GCN 20763) using the Palomar 48-inch Oschin telescope (P48) on the night of 2017-03-01 UTC (delay due to inclement weather). We imaged 84 fields spanning 633 square degrees, with a 17% chance of containing the true location of G275404. Of these, 47 fields (361 square degrees) were imaged twice, containing 11% of the probability of containing G275404, and searched for transient candidates. During preliminary sifting through candidate variable sources using image subtraction by our IPAC (Masci et al. 2016) and NERSC (Cao et al. 2016) pipelines, a total of 140 candidates were saved in the fields imaged. Applying standard iPTF vetting procedures and removing transients with a history of previous variability, we flagged 27 optical transient candidates in the 90% localization contour of G275404, listed below, for further follow-up. Name RA Dec UTC R-mag z Notes iPTF17bpa 150.966591 1.095135 09:07 18.72 0.0456 specz; off center from host iPTF17bpb 154.902074 -2.992951 09:25 19.56 0.0511 photz; pstar=0.016; nuclear? iPTF17bpc 155.671912 -3.647882 09:25 19.31 pstar=0.001; nuclear? iPTF17bpd 155.181672 -4.163867 09:25 19.28 pstar=0.804; nuclear/stellar? iPTF17bpk 157.626592 -11.121047 10:20 19.63 nuclear/stellar? iPTF17bpm 161.324311 -14.376753 10:04 19.26 pstar=0.229; nuclear/stellar? iPTF17bpn 161.238427 -14.017486 10:04 19.56 pstar=0.46; nuclear/stellar? iPTF17bpo 158.494163 -12.65084 10:02 19.03 pstar=0.96; nuclear/stellar? iPTF17bps 161.952768 -15.243493 10:04 19.76 hostless (very slow mover?) iPTF17bpt 157.657157 -7.372908 09:29 19.49 fading (0.5 mag intra-night); pstar=0.89; nuclear/stellar? iPTF17bpu 157.559861 -6.799173 09:29 19.81 pstar=0.612; nuclear/stellar? iPTF17bpy 156.687516 -7.684226 09:29 19.98 pstar=0.933; nuclear/stellar? iPTF17bqc 158.470076 -11.493302 10:02 19.62 pstar=0.717; nuclear/stellar? iPTF17bqh 156.749276 -10.358467 10:00 19.49 rising (0.4 mag intra-night); nuclear/stellar? iPTF17bqi 156.87908 -7.04181 09:29 19.41 pstar=0.962; nuclear/stellar? iPTF17bqk 162.188261 -15.49746 10:04 19.76 nuclear/stellar? iPTF17bqz 157.651689 -7.696641 09:29 19.83 pstar=0.885; nuclear/stellar? iPTF17bro 288.344596 58.81211 10:59 19.82 rising (0.5 mag intra-night), nuclear? iPTF17brp 291.671757 79.220007 11:47 19.42 0.076 photz; pstar=0.056; off center from host galaxy iPTF17brr 289.432632 79.995864 11:47 19.88 pstar=0.898; nuclear/stellar? iPTF17bru 294.594305 63.706556 11:36 19.95 off center from host galaxy iPTF17bsd 156.642225 -10.970993 10:00 19.68 rising (0.3 mag intra-night); nuclear iPTF17bsi 297.077103 78.352918 12:01 19.08 0.014 photz; off center from host galaxy iPTF17bst 156.998904 -7.216924 09:29 19.87 pstar=0.973; nuclear/stellar? iPTF17btb 302.938179 72.930472 12:03 18.56 nuclear/stellar? iPTF17btc 309.740925 72.580678 12:03 18.97 nuclear/stellar? iPTF17bth 307.33055 68.241724 12:05 19.31 nuclear/stellar? Positions are stated in the ICRS. Discovery times are noted in UTC hh:mm on 2017-03-01. Magnitudes are based on image subtraction and in the Mould R filter, calibrated with respect to point sources in SDSS as described in Ofek et al. 2012. We caution that many candidates are outside the SDSS footprint and lack a secure star/galaxy classification for the underlying source. We flag these as "nuclear/stellar?". Where available, we provide machine-learning probability scores on whether the underlying source is a galaxy/star (0/1) (Miller et al. 2016). We encourage spectroscopic classification of these candidates. In particular, we highlight iPTF17bpt, iPTF17bqh, iPTF17bsd as fast-evolving by more than 0.3 mag in the same night; iPTF17bpa and iPTF17bsi as local transients (d < 200 Mpc), and iPTF17bpa and iPTF17btb as bright transients (m < 19 mag). We are grateful to the Palomar crew (especially John Henning, Jeff Zolkower, Carolyn Heffner, Jamey Eriksen, Nick Ganciu) for their hard work in reviving a faulty declination encoder essential to collecting this dataset during the last two days of iPTF survey operations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20794 SUBJECT: LIGO/Virgo G268556, G270580, G274296, and G275404: Konus-Wind observations DATE: 17/03/02 14:42:59 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 times of the LIGO events G268556, G270580, and G274296 (hereafter T0; LIGO/VIRGO Collaboration GCN Circ. 20364, 20486, and 20689, respectively). A waiting mode data gap (~100 s in duration) occurred at the time of the LIGO event G275404 (LIGO/VIRGO Collaboration GCN Circ. 20738), so it was excluded from the analysis. We found no significant (> 5 sigma) detection on temporal scales from 2.944 s to 100 s using waiting mode data from both KW detectors S1 and S2 within ^[+/- 100 s from each of the LIGO triggers. The table below contains, for each of the triggers, estimates for upper limits (90% conf.) on the fluence (S) 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^K=-0.5 and Ep=500 keV); and on the peak flux (Fpeak; on the 2.944 s scale) for a typical long GRB spectrum (the Band function with alpha=-1, beta=-2.5, and Ep=300 keV), both in the 10 keV - 10 MeV band. UID T0, UTC S* Fpeak** G274296 2017-02-17 06:05:53.050 9.6 3.2 G270580 2017-01-20 12:30:59.350 9.9 3.1 G268556 2017-01-04 10:11:58.599 9.2 3.3 * in units of 10^-7 erg/cm2 ** in units of 10^-7 erg/cm2/s All the quoted values are preliminary. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20800 SUBJECT: LIGO/Virgo G275404: Nearby Galaxies in the Localization Volume DATE: 17/03/03 01:11:14 GMT FROM: Mansi M. Kasliwal at Caltech David O. Cook (Caltech), Angela Van Sistine (UW Milwaukee), Leo Singer (NASA/GSFC), and M. M. Kasliwal (Caltech) report on behalf of the iPTF (intermediate Palomar Transient Factory) and GROWTH (Global Relay of Observatories Watching Transients Happen) collaborations We spatially cross-matched the LIGO/Virgo G275697 trigger (90% containment volume; LVC GCN 20763) with our Census of the Local Universe (CLU; Cook et al. in prep) galaxy catalog and found 7361 galaxies. This catalog is a compilation of galaxies with existing redshifts from many sources (e.g., NED, SDSS, etc) and new galaxies from a 3PI four-filter narrow-band survey to look for redshifted Halpha emission out to 200 Mpc with the Palomar Oschin 48-inch telescope. Currently, the narrow-band survey is only calibrated inside the footprint of SDSS. Of the 7361 galaxies in the error volume, 6032 come from a compilation of known galaxies and 1329 are new, emission-line CLU galaxy candidates. We list here the top 20 galaxies sorted by star formation rate (SFR) and by stellar mass (Mstar) for galaxies whose location on the sky and distance falls in the 90% volume reported by the BAYESTAR probability sky map (Singer et al. 2016), where the 90% credible volume measures 3.3e6 Mpc^3. The sorted SFR list contains 2 new CLU galaxies with no previous spectroscopic redshifts, and the sorted mass list contains 1 new CLU galaxy. CLU J20203032+0734271 is an interacting triplet of galaxies, and CLU J08550651+1944566 may be an interacting pair. List of sorted SFRs: name ra dec distMpc Log(sfr_fuv, Msun/yr) Log(mstar, Msun) ----------------------- -------- -------- ------- --------------------- ---------------- II Zw 096 314.3496 17.1273 148.35 2.486 10.78 2MASX J10315733-1846333 157.9887 -18.7761 172.43 1.922 11.14 CLU J21083429+1804593 317.1430 18.0830 171.40 1.838 10.56 MRK 0704 139.6084 16.3053 125.21 1.807 11.45 MRK 1239 148.0796 -1.6121 85.34 1.756 11.63 ESO 567- G 025 152.9059 -21.2538 128.15 1.733 11.04 2MASX J20104645+0107108 302.6935 1.1197 110.63 1.639 10.32 NGC 2761 136.8779 18.4341 119.85 1.575 10.85 MCG -05-26-006 161.8030 -28.9211 146.22 1.573 10.79 UGC 11497 298.9081 2.1819 108.47 1.512 10.82 UGC 05025 141.5137 12.7343 124.85 1.507 11.04 2MASX J12313717-4758019 187.9048 -47.9672 119.47 1.473 10.96 CGCG 447-017 310.7770 21.6341 198.10 1.466 11.07 ESO 267- G 029 183.4678 -47.2737 77.79 1.452 10.51 CLU J08550651+1944566 133.7770 19.7489 52.82 1.447 8.56 2MASX J19512506+0432574 297.8542 4.5493 121.09 1.444 10.19 TOLOLO 00013 167.3347 -30.3636 177.31 1.429 10.68 2MASX J11143157-2935412 168.6316 -29.5948 129.19 1.428 10.31 2MASX J20353916+0816162 308.9133 8.2711 114.50 1.403 10.67 VV 637 150.8623 -1.5467 197.44 1.390 10.69 List of sorted stellar masses: name ra dec distMpc Log(sfr_fuv, Msun/yr) Log(mstar, Msun) ----------------------- -------- -------- ------- --------------------- ---------------- MRK 1239 148.0796 -1.6121 85.34 1.756 11.63 MRK 0704 139.6084 16.3053 125.21 1.807 11.45 2MASX J10315733-1846333 157.9887 -18.7761 172.43 1.922 11.14 CGCG 447-017 310.7770 21.6341 198.10 1.466 11.07 MCG -03-26-030 152.8289 -17.2044 129.25 0.015 11.05 UGC 05025 141.5137 12.7343 124.85 1.507 11.04 ESO 567- G 025 152.9059 -21.2538 128.15 1.733 11.04 NGC 2720 134.7836 11.1492 127.07 -0.271 11.04 UGC 05025 141.5140 12.7344 123.28 1.496 11.03 2MASX J10260948-2034149 156.5394 -20.5708 175.36 -0.036 11.03 CGCG 447-008 307.9770 18.4189 192.53 -0.068 11.03 2MASX J20235470+1341480 305.9779 13.6967 191.06 0.575 11.02 NGC 2819 139.5387 16.1981 129.13 -0.277 11.00 ESO 438- G 023 170.2215 -29.4031 127.39 0.430 10.99 2MASX J09493236-1406471 147.3848 -14.1132 179.73 0.209 10.99 2MASX J12313717-4758019 187.9048 -47.9672 119.47 1.473 10.96 UGC 11602 309.4789 10.6313 110.68 0.355 10.95 CLU J20203032+0734271 305.1260 7.5744 183.17 0.986 10.90 UGC 05182 145.6040 4.2832 122.75 -0.222 10.90 2MASX J10370833-2242401 159.2847 -22.7112 158.88 0.763 10.89 The SFRs are derived from GALEX all sky kron FUV magnitudes via the prescription of Murphy et al. (2011) and have been corrected for internal dust extinction using a combination of GALEX FUV and 22um ALLWISE fluxes (Hao et al. 2011). The quoted stellar masses are derived from 3.4um ALLWISE fluxes and a mass-to-light ratio of 0.5 (McGaugh & Schombert et al. 2015). AGN contributions to the SFRs and stellar masses are not corrected for. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20801 SUBJECT: LIGO/Virgo G275404: Additional iPTF Optical Transient Candidates DATE: 17/03/03 04:21:33 GMT FROM: Mansi M. Kasliwal at Caltech R. Lunnan (Caltech), S. Papadogiannakis (OKC), N. Blagorodnova (Caltech), A. A. Miller (Northwestern/Adler), L. P. Singer (NASA/GSFC), S. M. Adams (Caltech), C. Cannella (Caltech), S. B. Cenko (NASA/GSFC), R. Walters (Caltech), T. Barlow (Caltech), J. Rana (IUCAA), V. Bhalerao (IIT-B), Y. Cao (UW), R. Laher (IPAC), F. Masci (IPAC) and M.M. Kasliwal (Caltech) report on behalf of the iPTF (intermediate Palomar Transient Factory) and GROWTH (Global Relay of Observatories Watching Transients Happen) collaborations: We have continued tiled observations of LIGO/Virgo G275404 (LVC, GCN 20738) and LIGO/Virgo G275697 (LVC, GCN 20763) using the Palomar 48-inch Oschin telescope (P48). Including our first night of observations on 2017-03-01 UTC (GCN 20791) and a second night on 2017-03-02, we have observed a total of 256 fields spanning 1747 square degrees. We estimate a 20% chance that these fields contain the true location of G275404 and a 25% chance that they containing the true location of G275697. During preliminary sifting through candidate variable sources using image subtraction by our IPAC (Masci et al. 2016) and NERSC (Cao et al. 2016) pipelines, a total of 115 candidates were saved in the fields imaged. Applying standard iPTF vetting procedures and removing transients with a history of previous variability, we flagged 9 additional optical transient candidates in the 90% localization contour of G275404, listed below, for further follow-up. iPTF17buf 98.583906 76.596292 05:24 19.59 pstar=0.962; nuclear/stellar? iPTF17bug 97.67324 77.159053 05:24 18.6 0.0166 specz; nuclear iPTF17bur 295.1181 58.707877 11:38 19.14 pstar=0.016; nuclear/stellar? iPTF17buu 114.100254 74.505262 05:33 19.92 Hostless in iPTF reference but faint counterpart seen in PanSTARRS. iPTF17buw 127.499818 73.935927 06:08 20.23 pstar=0.948; nuclear/stellar? iPTF17bvo 133.140294 86.061384 06:11 19.55 nuclear; pstar=0.042 iPTF17bvt 115.702547 74.553167 05:33 19.57 nuclear/stellar?; looks like three-star blend in PS1 iPTF17bwl 150.611516 8.822758 08:23 18.77 0.114 specz; also detected 2017-03-01; nuclear; SDSS QSO iPTF17bxk 149.643558 6.963137 08:23 19.99 0.077 specz; offset 13.5" from the center of 2MASX J09583513+0657389 Two known transients detected by Pan-STARRS on 2017-02-16 also fall in this localization region and were recovered with iPTF : PS17bjk (iPTF17bez) and PS17bjd (iPTF17bfa). Positions are stated in the ICRS. Discovery times are noted in UTC hh:mm on 2017-03-02. Magnitudes are based on image subtraction and in the Mould R filter, calibrated with respect to point sources in SDSS as described in Ofek et al. 2012. We caution that many candidates are outside the SDSS footprint and lack a secure star/galaxy classification for the underlying source. We flag these as "nuclear/stellar?". Where available, we provide machine-learning probability scores on whether the underlying source is a galaxy/star (0/1) (Miller et al. 2016). We encourage spectroscopic classification of these candidates, and highlight iPTF17bug as a local candidate (d < 200 Mpc). We are grateful to the Palomar crew (John Henning, Jeff Zolkower, Carolyn Heffner, Jamey Eriksen, Nick Ganciu) for their hard work in reviving a faulty declination encoder essential to collecting this dataset during the last two days of iPTF survey operations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20809 SUBJECT: LIGO/Virgo G275404: Liverpool Telescope classification of EM candidates DATE: 17/03/03 17:16:51 GMT FROM: Chris Copperwheat at LJMU ArI C.M.Copperwheat (LJMU), I.A.Steele (LJMU) and A.S.Piascik (LJMU) report on behalf of D.Bersier (LJMU), M.Bode (LJMU), C.Collins (LJMU), M.Darnley (LJMU), D.Galloway (Monash), A.Gomboc (Nova Gorica), S.Kobayashi (LJMU), A. Levan (Warwick), P.Mazzali (LJMU), C.Mundell (Bath), E.Pian (Pisa), D. Pollacco (Warwick), D. Steeghs (Warwick), N.Tanvir (Leicester), K. Ulaczyk (Warwick), K.Wiersema (Leicester) and the GROWTH (Global Relay of Observatories Watching Transients Happen) collaboration. --- We report the following Liverpool Telescope follow-up observations of EM candidates originally reported in GCN #20790. Observations were made with the SPRAT spectrograph, and supernova classifications were obtained using SNID (Blondin & Tonry, 2007, ApJ, 666, 1024). iPTF17bqh was observed on 2017-03-02 at 23:58UT. The spectrum is generally featureless with some weak hints of Balmer lines in absorption, so we believe this source to be a dwarf nova in outburst. iPTF17bpt was observed on 2017-03-03 at 02:12UT. Based on a weather-affected spectrum we classify this transient as a type Ia SN at +18 days with z=0.595. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20810 SUBJECT: LIGO/Virgo G275404: PIRATE Observations DATE: 17/03/03 17:23:39 GMT FROM: Dean Roberts at PIRATE D. Roberts, M.Morrell & U. Kolb (The Open University) reporting on behalf of the PIRATE group: We observed 99 separate fields in two different regions of the G275404 bayestar skymap using our 0.43m robotic telescope at Teide Observatory, Tenerife, Spain. We acquired over 400 images across the first 6 nights of observations, all images were obtained using the R filter and 60s exposure length. Initial observations began at 2017-02-25T22:17:50, approximately 5 hours after the initial GCN alert was received. A detailed list of all the fields observed can be found on GraceDB under the EMObservations tab. Each FoV was 0.7x0.7 degrees centred around the given coordinates. Analysis is ongoing. -- The Open University is incorporated by Royal Charter (RC 000391), an exempt charity in England & Wales and a charity registered in Scotland (SC 038302). The Open University is authorised and regulated by the Financial Conduct Authority. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20811 SUBJECT: LIGO/Virgo G275404: HAWC follow-up DATE: 17/03/04 02:08:55 GMT FROM: Andrew Smith at U Maryland HAWC was operating and our real-time all-sky GRB monitoring analysis was running at the time of the G275404 event. At the time of the event, the HAWC detector was oriented at (α, δ) = (336.1°, 19.0°), local zenith. 33% of the LIGO/Virgo CWB probability contour fell within our observable field (0-45 deg zenith angle). We continuously perform a real-time search for counts above the steady-state cosmic-ray background using 4 sliding time windows (0.1, 1, 10, and 100 seconds) shifted forward in time by 10% of their width over the course of the entire observing period. Within each time window, we search the HAWC sky within 45 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 optimized 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 the gravitational-wave trigger. After the GW trigger was reported, we re-analyzed the data within ± 60 seconds of the gravitational-wave trigger contour on 3 timescales (1, 10, 100 sec) with a reduced threshold to account for the reduced number of trials. No significant candidates were identified. Additionally, we searched for longer duration emission. Since the most probable region of the contour was setting at the time of the trigger, we observed this region during the following transit, 17-25 hrs after the GW event. We did not find a significant excess. HAWC has a 5-sigma point-source sensitivity to a flux >1 TeV of ~2x10^-11/cm^2/s, about ~1 "crab unit", for a single transit observation. 67% of the LIGO/Virgo contour is within HAWC's observable declination range. 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: 20814 SUBJECT: LIGO/Virgo G275404: Liverpool Telescope classification of EM candidates DATE: 17/03/04 19:25:27 GMT FROM: Chris Copperwheat at LJMU ArI C.M.Copperwheat (LJMU), I.A.Steele (LJMU) and A.S.Piascik (LJMU) report on behalf of D.Bersier (LJMU), M.Bode (LJMU), C.Collins (LJMU), M.Darnley (LJMU), D.Galloway (Monash), A.Gomboc (Nova Gorica), S.Kobayashi (LJMU), A. Levan (Warwick), P.Mazzali (LJMU), C.Mundell (Bath), E.Pian (Pisa), D. Pollacco (Warwick), D. Steeghs (Warwick), N.Tanvir (Leicester), K. Ulaczyk (Warwick), K.Wiersema (Leicester) and the GROWTH (Global Relay of Observatories Watching Transients Happen) collaboration. --- We report the following Liverpool Telescope follow-up observations of EM candidates originally reported in GCNs #20790 and #20801. Observations were made with the SPRAT spectrograph, and supernova classifications were obtained using SNID (Blondin & Tonry, 2007, ApJ, 666, 1024). iPTF17bug was observed on 2017-03-03 at 20:19UT. This is a nuclear source, and the spectrum we obtain seems to be dominated by the host galaxy. iPTF17bpa was observed on 2017-03-03 at 22:37UT. This source was reported to be off-centre from it's host galaxy but we do not detect a transient above the background galaxy emission in our acquisition image. The spectrum seems to be galaxy dominated. iPTF17bpt was observed on 2017-03-03 at 23:17UT. We classify this source as a type Ia Supernova with z=0.074. A type Ib classification is also a possibility. Note that this classification replaces the classification with erroneously high z reported in GCN #20809. iPTF17bsi was observed on 2017-03-04 at 04:56UT. SNID classifies this source as a Type II supernova (possibly IIP) at 2.7 days after peak with z=0.028. This is significantly higher than the photometric z = 0.014 reported for the host galaxy in GCN #20790. iPTF17btb was observed on 2017-03-04 at 05:29UT. We observe a bright point source with a featureless spectrum - this is likely a dwarf nova in outburst. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20816 SUBJECT: LIGO/Virgo G275404: P200/DBSP Classification of iPTF Candidates DATE: 17/03/05 07:21:01 GMT FROM: Mansi M. Kasliwal at Caltech N. Blagorodnova, K. De, R. Lunnan, M. Balokovic, N. Kamraj, M. Heida, D. Stern and M. M. Kasliwal (Caltech) report on behalf of the iPTF (intermediate Palomar Transient Factory) and GROWTH (Global Relay of Observatories Watching Transients Happen) collaborations On UT 2017-03-04, we spectroscopically classified the following iPTF optical transient candidates (LVC GCN#20801, LVC GCN#20790) using the Double Beam Spectrograph (Oke & Gunn 1982) on the Palomar 200-inch Hale Telescope. All spectra were reduced using the pyraf-dbsp pipeline (Bellm & Sesar 2016). Classification were done with SNID (Blondin & Tonry, 2007) and Superfit (Howell et al. 2005). Name, Redshift, Classification, Notes iPTF17bug, z=0.0167, Spectrum dominated by galaxy light (Consistent with LVC GCN 20814) iPTF17bxk, z=0.077, SN IIn, Best match is 2005cl at +15d iPTF17bpa, z=0.046, Spectrum dominated by host galaxy light, just outside 90% contour line (Consistent with LVC GCN 20814) iPTF17bpb, z=0.049, Spectrum dominated by host galaxy light iPTF17bpc, z=0.039, Spectrum dominated by host galaxy light iPTF17bsd, z=0.116, Spectrum dominated by host galaxy light iPTF17bro, z=0.055, Spectrum dominated by host galaxy light iPTF17bvo, z=0.0915, AGN?, double-peaked Balmer line //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20834 SUBJECT: LIGO/Virgo G275404 and AGL J1914+1043: INTEGRAL follow-up DATE: 17/03/07 22:38:53 GMT FROM: Volodymyr Savchenko at APC,Paris V. Savchenko (ISDC, University of Geneva, CH) on behalf of the INTEGRAL group: C. Ferrigno ((ISDC, University of Geneva, CH), S. Mereghetti (IASF-Milano, 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, Saclay/CEA, France) A. Lutovinov (IKI, Russia) J.P. Roques (CESR, France) R. Sunyaev (IKI, Russia) P. Ubertini (IAPS-Roma, Italy) INTEGRAL performed a target-of-opportunity (ToO) observation containing the peak of the LIGO localization probability of G275404 (Sachdev et al 2017, GCN 20738) and its possible gamma-ray counterpart AGL J1914+1043 (Tavani et al 2017, GCN 20754). In total 56% of the LIGO probability and the whole probable localization region of AGL J1914+1043 were observed in the field of view (FoV) of the INTEGRAL instruments. The observation containing the peak localization probability of G275404 peak (RA= 299.1 Dec=49.3), started 81.5 hours after the G275404 trigger time (2017-02-25 18:30:21.4 UTC , T0 hereafter) from 2017-03-01 04:09:58 UTC to 2017-03-02 05:45:58 UTC, corresponding to an on-target time of 85.5 ks. We covered in total 40% of LIGO localization probability with INTEGRAL/IBIS FoV. Every single hour-long spacecraft pointing contained about 30% of the LIGO localization probability. The observation of AGL J1914+1043 started at T0+107.5 hours and spanned from 2017-03-02 05:57:54 UTC to 2017-03-03 07:03:05 UTC, with a total on-target time of 86.5 ks and including an extended region within a distance of about 15 degrees from the target, securely encompassing the region of probable localization reported by AGILE (4 deg 68% containment + 1 deg systematic error). This observation includes 16% of G275404 localization in INTEGRAL/IBIS FoV and every single hour-long instrument pointing contained about 13% of the LIGO localization probability. Additionally, by chance, INTEGRAL observed a non-negligible fraction of the G275404 probability before the start of the dedicated ToO. Despite limited coverage, these observations are useful, since they were performed during the LIGO trigger and as well as immediately before and after. The observation of the Galactic Bulge region from 2017-02-26T12:22:54 to 2017-02-26T16:03:52.396 collected 12.5ks of data covering 1.5% of LIGO probability, complementary to that of the ToO observation. The observation of the Norma Region between 2017-02-27T07:13:58.431 and 2017-02-28T01:48:14.473 collected 61ks of data covering additionally 2% of the LIGO probability. We investigated the data collected by INTEGRAL IBIS/ISGRI and JEM-X. We did not find any new significant sources in the 90% localization region of G275404. In INTEGRAL/ISGRI observation of AGL J1914+1043 data between 25 and 80 keV we have found a weak excess with an SNR of 4.3 at RA=292.27 Dec=8.14 (radius of 5 arcmin, 90% containment), 4.6 deg from the center of AGILE localization (RA=288.43 deg, DEC=10.72 deg, and error radius R = 4 deg at 68% confidence + 1 deg systematic error). We have split the observation in two periods of equal duration, and found that this excess is not detected with SNR more than 4 in any of them, hence revealing no sign of evolution. If real, the excess would correspond to a source with an average flux of 5.1+/-1.2 mCrab (5.1+-1.2e-11 erg/cm2/s) in the 25-80 keV band and 3.5+/-1.1 mCrab (2.9+-0.9e-11 erg/cm2/s) in 25-40 keV band. While this possible source is located in a region frequently observed by INTEGRAL (for a total of 14Ms between 2003 and 2017), no possible detection was previously reported at its position. We estimate a probability of this excess happening randomly within the 5 degree radius of the AGILE localization to 3.5% or a significance of 2.1 sigma. We derived an upper limit on the flux of a new source at the peak of the LIGO localization probability of 6 mCrab (1.9e-10 erg/cm2/s) in the 3-35 keV band, 3.6 mCrab (3.6e-11 erg/cm2/s) in the 25-80 keV band, and 7 mCrab (8.2x10-11 erg/cm2/s) in the 80-200 keV band. The upper limit depends on the source position in the field of view. About 40% of G275404 is observed with the sensitivity of down to 10 mCrab or better. The localization region of another LIGO event, G275697 (Siellez et al 2017, GCN 20763), was in the FoV of the INTEGRAL instruments, with the 30% of the LIGO localization observed by IBIS/ISGRI at any time from the LIGO trigger time to 3.5 days after. At the moment of the LIGO trigger as well as from -0.5 days to 0.3 days around it up to 8% of the probability was in the ISGRI FoV, while at any other moment until 3.5 days after the trigger up to 15% of the probability was in the FoV. We note that omni-directional INTEGRAL/SPI-ACS observations around the G275404 and G275697 triggers are reported in LIGO/Virgo Circulars 20755 and GCN 20768. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20840 SUBJECT: LIGO/Virgo G275404: Updated localization from LIGO data DATE: 17/03/08 22:30:50 GMT FROM: Alex Urban at Caltech The LIGO Scientific Collaboration and Virgo report: We have completed an initial Bayesian parameter estimation analysis of the LIGO data around the time of the compact binary coalescence (CBC) event candidate G275404 (GCN 20738) using LALInference (Veitch et al., PRD 91, 042003). This analysis used the IMRPhenomPv2 waveform approximation, which includes the inspiral, merger, and ringdown phases of the signal and accounts for the effects of spin precession. We accounted for systematic errors due to uncertainty in the calibration of the detectors' responses of up to 10% in amplitude and 10 degrees in phase. This follow-up analysis also used different, more conservative assumptions on the detector noise properties. The updated localization, LALInference.fits.gz, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/events/G275404 The localization has arcs similar to the rapid BAYESTAR sky map, but broader, and the conservative assumptions mentioned above result in this case in a much larger area in the sky consistent with the observed data. The 50% credible region spans 2000 deg2 and the 90% credible region spans 17000 deg2 due to a diffuse component in the probability distribution. This parameter estimation analysis does not influence our estimation of the significance of this event. It remains a marginal candidate with a false alarm rate of about one in two months as reported in our original Circular. If the signal is astrophysical, then the mass estimates are consistent with a NSNS or NSBH binary. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20842 SUBJECT: LIGO/Virgo G275404: Swift-XRT observations of sources in the AGILE error region DATE: 17/03/09 14:45:19 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), P. Giommi (ASI), C. Gronwall (PSU), H.A. Krimm (CRESST/GSFC/USRA), N.P.M. Kuin (UCL-MSSL), A.Y. Lien (GSFC/UMBC), 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) on behalf of the Swift team and Francesco Verrecchia (ASDC) and Marco Tavani (INAF / University of Rome Tor Vergata) on behalf of the AGILE team report: Swift-XRT has performed pointed observations of two sources within the error region of the AGILE-GRID transient AGL J1914+1043 (Tavani et al. LVC Circ. 20754): the IR transient reported by Yoshida et al (LVC Circ. 20784) and the Galactic microquasar GRS 1915+105, observing each field for 1ks. No X-ray source is detected at the location of the IR transient, with a 3-sigma upper limit of 9.7e-3 ct/sec. Assuming a power-law spectrum with Gamma=1.7 and NH=1.43e22 cm^-2 (the Galactic column along this line of sight; Willingale et al. 2013) this corresponds to an observed X-ray flux of 7.1e-13 erg cm^-2 s^-1. GRS 1915+105 is a known X-ray emitter and is clearly detected in the XRT observations, with a mean count-rate of 87.8 (+1.63, -2.05) ct/sec, which is ~20% lower than seen in Swift observations from 2016 November. This circular is an official produce of the Swift and AGILE teams. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20869 SUBJECT: LIGO/Virgo G275404: Medicina radio follow-up of near-infrared DATE: 17/03/14 17:19:16 GMT FROM: Francesco Verrecchia at ASDC, INAF-OAR M. Pilia, A. Pellizzoni (INAF/OA-Cagliari), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), S. Loru, A. Trois (INAF/OA-Cagliari), F. Verrecchia, F. Lucarelli (ASDC and INAF/OAR), C. Pittori (ASDC), M. Cardillo, G. Minervini, P. Munar-Adrover, G. Piano, A. Ursi, A. Argan, Y. Evangelista (INAF/IAPS), A. Bulgarelli, V. Fioretti, A. Zoli, N. Parmiggiani, F. Fuschino (INAF/IASF-Bo), M. Marisaldi (INAF/IASF-Bo and Bergen University), F. Longo (Univ. Trieste and INFN Trieste), I. Donnarumma (ASI), A. Giuliani (INAF/IASF-Mi), report on behalf of the AGILE Team: Following the LIGO/VIRGO event G275404, we performed radio C-band (5 GHz) single-dish imaging centered at the position of the infrared transient candidate detected by the Kanata Telescope HONIR camera at RA=19:10:31.46, DEC=+07:53:52.0 (Yoshida et al. GCN 20784), placed at the edge of the Galactic Bubble N82, seen in IR by Spitzer (Churchwell et al., 2006, ApJ, 649, 759). This source was within the error box of the transient candidate found in the AGILE-GRID data, AGL J1914+1043 (Tavani et al. GCN 20754). The observations were performed using the 32-m Medicina radio telescope on 2017-03-06 UT. We detected a bright radio source at the center of the observed field of 1 x 1 deg. The source appears slightly larger than the 7.4 arcmin beam of the receiver. The flux density at 5 GHz was 3.3 +/- 0.5 Jy (MJD 57818.4375). The source emission, peaking at RA=19:10:30, DEC=+07:52:00, is compatible with the coordinates of the Galactic Bubble N82, including the NIR Kanata source. Within the half-power-beam-width from the source centroid, 7 radio sources are present, mostly unidentified. We report below a list of the sources, their coordinates, flux density, radius and possible association (source SIMBAD): NAME R.A. DEC FLUX(Jy) R(') ASSOC. ------------------------------------------------------------------------- GPA 042.13-0.62 19:10:32.1 +07:53:22 2.81(@8.35GHz) 5 - G042.114-0.622 19:10:31.7 +07:52:40 0.35(@1.4GHz) - extragalactic GB6 B1908+0747 19:10:28.8 +07:52:28 0.39(@327MHz) <~3 HII? HSNH 115 19:10:31.6 +07:52:18 2.1(@10GHz) 3.3 - RFS 713 19:10:30.0 +07:51:51 3.3(@2.7GHz) 6 - GP 1908+0746 19:10:33.7 +07:51:51 0.54(@327MHz) 6 - RRF 312 19:10:21.3 +07:50:34 5.5(@1.4GHz) 13.3 - Variability analysis on long and short time-scales are ongoing. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20898 SUBJECT: LIGO/Virgo G275404: P200/DBSP Classification of iPTF Candidates DATE: 17/03/17 22:06:10 GMT FROM: Mansi M. Kasliwal at Caltech S. M. Adams, J. Jencson, K. Burdge, N. Blagorodnova, M. M. Kasliwal (Caltech) and F. Taddia (OKC) report on behalf of the iPTF (intermediate Palomar Transient Factory) and GROWTH (Global Relay of Observatories Watching Transients Happen) collaborations On UT 2017-03-07 and 2017-03-16, we spectroscopically classified the following iPTF optical transient candidates (LVC GCN#20790) using the Double Beam Spectrograph (Oke & Gunn 1982) on the Palomar 200-inch Hale Telescope. All spectra were reduced using the pyraf-dbsp pipeline (Bellm & Sesar 2016) and spectral matching done using SNID and Superfit. Name, Redshift, Classification, Notes (2017-03-07) iPTF17bps, z=0.109, SN Ia, best match is SN2006ev at +11d iPTF17bpt, z=0.785, AGN (but see LVC GCN # 20814) (2017-03-16) iPTF17bru, z=0.103, SN Ia, best match is SN1989B +13d iPTF17bsi, z=0.031, SN II, best match is SN2004dj +0d (consistent with LVC GCN # 20814) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20981 SUBJECT: LIGO/Virgo G275404: European VLBI Network (EVN) follow-up of the near-IR transient in the AGL J1914+1043 field DATE: 17/04/05 14:50:35 GMT FROM: Zsolt Paragi at Euro VLBI Zsolt Paragi (JIVE) Tao An (Shanghai Astronomical Observatory) Philippe Bacon (APC Université Paris Diderot) Rob Beswick (JBO-Manchester University) Eric Chassande-Mottin (APC Université Paris Diderot) Sándor Frey (Konkoly Observatory) Marcello Giroletti (IRA-INAF) Peter Jonker (SRON) Mark Kettenis (JIVE) Benito Marcote (JIVE) Arpad Szomoru (JIVE) Huib van Langevelde (JIVE) Jun Yang (Onsala Space Observatory) for the Euro VLBI team We observed the near-IR transient (Yoshida et al., GCN 20784) within the error circle of AGL J1914+1043 (Tavani et al., GCN 20754) with the real-time very long baseline interferometry (e-VLBI) technique using the EVN at 4.9 GHz between 2:06—11:48 UT on 24 March 2017. There is no compact radio emission detected on milliarcsecond scales within +-4 arcseconds of the near-IR transient coordinates of RA=19:10:31.46, DEC=+07:53:52.0, with a 6 sigma upper limit of 105 microJy/beam. More details on the Euro VLBI team observations: Participating EVN telescopes were Effelsberg, Irbene, Jodrell Bank MkII, Medicina, Onsala, Noto, Torun, Westerbork (single dish), Yebes, Arecibo, Hartebeesthoek and Tianma. The observing frequency of 4.9 GHz was preferred over 1.6 GHz because of strong scatter-broadening in this region. The phase-referencing calibrator was J1922+0841, 3 degrees away from the target; it has resolved structure on mas scales, but strong fringes were detected. The cycle time was 1:30-3:30 minutes. Total on-source integration time on the target was 4.1 hours. A number of other calibrators/calibrator candidates were observed as well, most notably J1909+0756 (11 arcminutes from the target), that was detected as a ~30 mJy but quite resolved source (~10 mas East-West; not useful as calibrator beyond 10 Mlambda at this frequency). None of the sources reported by Medicina single dish observations at 5 GHz (Pilia et al., GCN 20869) were detected (we had 3 times 1-minute scans on each). The data were correlated real-time with the EVN Software Correlator at JIVE (SFXC) and processed according to standard procedures, using measured system temperature for most telescopes (for Arecibo, Noto, Jodrell Bank we used nominal SEFDs). The EVN is a joint facility of independent European, African, Asian, and North American radio astronomy institutes. Scientific results from data presented in this publication are derived from the following EVN project code: RP027. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20982 SUBJECT: LIGO/Virgo G275404: Update on significance from offline analyses DATE: 17/04/05 17:03:39 GMT FROM: Alexander H Nitz at Albert Einstein Inst/Hannover The LIGO Scientific Collaboration and Virgo report: We report an update on the significance of the gravitational-wave trigger G275404 (GCN 20738). This trigger was reported by the online PyCBC search with a false alarm rate (FAR) of 6 per year; i.e. background noise in the detectors produces 6 triggers per year as loud as G275404 in the PyCBC low-latency search. This trigger had low significance, but passed the FAR threshold of ~ 1 / month for generating an alert. We have completed the offline search over the time containing G275404 using the PyCBC (Usman et al. 2016, CQG 33, 215004) and GstLAL (Messick et al. 2016, PRD 95, 042001) searches. These offline analyses provide the final significance for candidate events. Neither search produced a significant trigger at the time of G275404. We conclude that G275404 is not a trigger of interest and does not warrant further follow-up. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21010 SUBJECT: LIGO/Virgo G275404: DLT40 follow-up observation DATE: 17/04/14 17:53:57 GMT FROM: Sheng Yang at UC Davis Sheng Yang (INAF-OAPd, UC Davis), Stefano Valenti (UC Davis), David Sand (TTU), Leonardo Tartaglia (TTU, UC Davis), Enrico Cappellaro (INAF-OAPd), Dan Reichart, Josh Haislip (UNC), G. Hosseinzadeh, I. Arcavi, D. A. Howell, C. McCully (Las Cumbres Obs./UCSB) report on behalf of the Gravitational Wave Follow-Up by DLT40. We report the observation of 50 galaxies within the LVC error region for the GW trigger G275404 using the 'bayestar' GW localization map from 2017-2-26 to 2017-3-9. Starting from 2017-3-9 (until 2017-3-12) we observed 84 galaxies using the update LALInference localization map. We selected galaxies from the GWGC catalogue within 80.0% of the trigger error region, within a distance of 40.0 Mpc, brighter than -17.5 mag and at a Declination < 20 degree. Those selected galaxies have been observed using the Prompt 5 telescope and they are part of the ongoing DLT40 search. The first 50 galaxies represent the 3.9% of all galaxies in the Glade catalogue within 40.0 Mpc and within the LVC error region for the GW trigger. They also contain 12.7% of all B band luminosity of those galaxies. The 84 galaxies, observed after 2017-3-9, represent the 1.5% of all galaxies and contains 9.7% of all B band luminosity. The DLT40 search limit magnitude, for those galaxies is 19.2 (open filter scaled to r band). We found one SN Ia, SN2017cbv/DLT17u, in NGC5642 on 2017-3-8, which is only 16 Mpc away. Our follow-up observations of SN2017cbv/DLT17u with Las Cumbres Observatory telescopes show that SN2017cbv/DLT17u has recently reached its maximum luminosity (Bmag ~ 11.79) 17.7 days after discovery. Giving the typical rise time of SNe Ia (18.98 ± 0.54 days, Firth, R. E., et al. 2014, MNRAS 446, p.3895-3910), SN2017cbv was discovered very close to explosion and we can then exclude that SN2017cbv is related to the GW event that occurred ~ 2 weeks before the explosion epoch of SN2017cbv. Below follow the list of galaxies observed: Name RA(J2000) DEC(J2000) Dist(Mpc) BMAG KMAG OBS_WINDOW(JD) ESO176-006 224.29 -54.39 38.01 -21.5 -24.4 2457821.57-2457825.39 NGC4696 192.20 -41.31 35.48 -21.4 -25.6 2457821.57-2457825.39 ESO380-006 183.89 -35.62 38.93 -21.3 -24.7 2457821.57-2457825.39 NGC6384 263.10 7.0603 25.94 -21.2 -24.5 2457821.57-2457825.39 NGC3962 178.66 -13.97 35.32 -21.2 -25.0 2457821.57-2457825.39 NGC5078 199.95 -27.41 27.67 -21.2 -25.0 2457821.57-2457825.39 NGC4603 190.23 -40.97 33.11 -21.2 -24.2 2457821.57-2457825.39 NGC5643 218.16 -44.17 18.45 -21.1 -24.1 2457821.57-2457825.39 NGC5266 205.75 -48.16 38.02 -21.1 -25.4 2457821.57-2457825.39 IC3253 185.93 -34.62 34.67 -21.0 -23.5 2451870.67-2457825.39 NGC3706 172.43 -36.39 38.02 -21.0 -24.9 2457821.57-2457825.39 NGC6574 272.96 14.981 38.91 -20.9 -24.5 2457821.57-2457825.39 NGC3923 177.75 -28.80 22.91 -20.9 -25.3 2451870.67-2457825.39 NGC3338 160.53 13.747 24.43 -20.9 -23.8 2457821.57-2457825.39 NGC5156 202.18 -48.91 36.98 -20.9 -24.1 2457821.57-2457825.39 ESO320-026 177.45 -38.78 38.02 -20.9 -24.2 2457821.57-2457825.39 NGC4976 197.15 -49.50 17.3 -20.9 -24.3 2457821.57-2457825.39 ESO271-022 213.37 -45.41 38.14 -20.8 -23.1 2457821.57-2457825.39 NGC6555 271.95 17.604 33.42 -20.8 -22.7 2457821.57-2457825.39 IC2977 178.81 -37.69 39.01 -20.8 -23.8 2457821.57-2457825.39 NGC5061 199.52 -26.83 24.21 -20.8 -24.6 2457821.57-2457825.39 IC4351 209.47 -29.31 27.54 -20.8 -24.1 2457821.57-2457825.39 NGC3749 173.97 -37.99 38.02 -20.8 -24.1 2457821.57-2457825.39 NGC3672 171.26 -9.795 23.66 -20.7 -23.6 2457821.57-2457825.39 NGC3585 168.32 -26.75 20.05 -20.7 -24.8 2457821.57-2457825.39 NGC5266A 205.15 -48.34 38.02 -20.7 -22.2 2457821.57-2457825.39 ESO442-026 193.05 -29.84 34.94 -20.7 -24.2 2457821.57-2457825.39 NGC5101 200.44 -27.43 24.21 -20.6 -24.7 2457821.57-2457825.39 ESO269-057 197.51 -46.43 36.98 -20.6 -24.0 2457821.57-2457825.39 NGC4373A 186.40 -39.31 37.33 -20.6 -24.0 2457821.57-2457825.39 PGC086291 282.99 11.876 38.02 -20.6 -24.0 2451870.67-2457825.39 NGC4444 187.15 -43.26 36.98 -20.6 -23.4 2457821.57-2457825.39 PGC054411 228.64 -52.98 19.36 -20.6 -24.2 2457821.57-2457825.39 NGC5688 219.89 -45.01 30.9 -20.5 -24.1 2457821.57-2457825.39 IC4214 199.42 -32.10 28.84 -20.5 -24.0 2457821.57-2457825.39 NGC3742 173.88 -37.95 38.61 -20.5 -24.2 2457821.57-2457825.39 NGC4112 181.78 -40.20 34.67 -20.5 -23.4 2457821.57-2457825.39 ESO221-010 207.73 -49.05 38.02 -20.5 -23.6 2457821.57-2457825.39 NGC3904 177.30 -29.27 28.31 -20.5 -24.5 2451870.67-2457825.39 NGC4219 184.11 -43.32 20.99 -20.5 -23.5 2457821.57-2457825.39 NGC3783 174.75 -37.73 38.02 -20.5 -24.2 2457821.57-2457825.39 ESO320-031 178.52 -39.86 38.18 -20.4 -24.8 2457821.57-2457825.39 ESO385-030 217.33 -33.45 34.33 -20.4 -24.0 2457821.57-2457825.39 NGC5219 204.67 -45.85 36.98 -20.4 -22.8 2457821.57-2457825.39 NGC2992 146.42 -14.32 28.84 -20.3 -23.7 2457821.57-2457825.39 NGC4767 193.47 -39.71 32.81 -20.3 -24.3 2457821.57-2457825.39 ESO175-005 214.44 -52.83 37.36 -20.3 -20.2 2457821.57-2457825.39 IC3370 186.90 -39.33 26.79 -20.3 -24.2 2457821.57-2457825.39 ESO380-019 185.50 -35.79 38.02 -20.3 -24.2 2451870.67-2457825.39 PGC046029 198.58 -46.12 36.98 -20.3 -24.3 2457821.57-2457825.39 NGC5063 199.60 -35.35 33.39 -20.3 -23.2 2457821.57-2457825.39 NGC5365 209.46 -43.93 32.36 -20.3 -24.6 2457821.57-2457825.39 ESO321-025 185.42 -39.76 29.38 -20.3 -22.5 2457821.57-2457825.39 NGC4947 196.33 -35.33 27.8 -20.3 -23.1 2451870.67-2457825.39 NGC5085 200.07 -24.44 24.21 -20.3 -22.9 2457821.57-2457825.39 NGC4105 181.67 -29.76 26.55 -20.3 -24.5 2451870.67-2457825.39 NGC3169 153.56 3.4664 18.45 -20.3 -24.0 2457821.57-2457825.39 ESO221-014 208.02 -48.17 35.81 -20.2 -23.1 2457821.57-2457825.39 NGC5365A 209.16 -44.00 36.98 -20.2 -24.0 2457821.57-2457825.39 ESO221-025 211.89 -48.39 38.93 -20.2 -19.4 2457821.57-2457825.39 ESO320-030 178.29 -39.13 38.02 -20.2 -23.6 2457821.57-2457825.39 NGC3459 163.68 -17.04 31.61 -20.2 -22.4 2451870.67-2457825.39 NGC2967 145.51 0.3365 29.92 -20.2 -23.4 2457821.57-2457825.39 IC4197 197.01 -23.79 34.1 -20.2 -23.3 2457821.57-2457825.39 NGC4304 185.55 -33.48 34.67 -20.2 -23.6 2451870.67-2457825.39 ESO377-024 168.13 -36.42 38.21 -20.2 -22.9 2457821.57-2457825.39 NGC4835 194.53 -46.26 20.14 -20.2 -23.3 2457821.57-2457825.39 NGC5483 212.60 -43.32 24.21 -20.2 -23.4 2457821.57-2457825.39 IC4444 217.91 -43.41 25.35 -20.2 -23.4 2457821.57-2457825.39 ESO507-032 193.06 -26.30 20.82 -20.2 -22.3 2457821.57-2457825.39 NGC6570 272.78 14.093 33.42 -20.2 -22.7 2457821.57-2457825.39 NGC5188 202.86 -34.79 28.84 -20.2 -23.7 2457821.57-2457825.39 NGC4993 197.44 -23.38 33.81 -20.2 -23.4 2457821.57-2457825.39 NGC5494 213.1 -30.64 31.19 -20.1 -23.4 2457821.57-2457825.39 NGC3368 161.69 11.819 10.47 -20.1 -23.7 2457821.57-2457825.39 ESO221-020 209.59 -48.47 38.29 -20.1 -23.6 2457821.57-2457825.39 ESO321-016 183.86 -38.14 38.02 -20.1 -21.9 2457821.57-2457825.39 ESO380-050 189.58 -35.61 38.02 -20.1 -20.5 2451870.67-2457825.39 NGC3115 151.30 -7.718 10.33 -20.1 -24.1 2457821.57-2457825.39 IC0764 182.55 -29.73 21.18 -20.1 -21.9 2451870.67-2457825.39 ESO221-026 212.09 -47.97 20.31 -20.1 -23.9 2457821.57-2457825.39 NGC4462 187.33 -23.16 23.12 -20.1 -23.3 2457821.57-2457825.39 ESO386-039 224.10 -37.60 36.98 -20.1 -22.8 2457821.57-2457825.39 ESO221-012 207.88 -48.08 38.02 -20.1 -21.9 2457821.57-2457825.39 PGC033108 164.90 -15.52 35.63 -20.0 -21.2 2451870.67-2457821.57 ESO441-017 182.78 -31.12 24.24 -19.9 -21.0 2451870.67-2457821.57 NGC3321 159.71 -11.64 33.88 -19.8 -22.1 2451870.67-2457821.57 NGC3044 148.42 1.5796 21.68 -19.8 -22.6 2451870.67-2457821.57 NGC3885 176.69 -27.92 21.88 -19.7 -23.3 2451870.67-2457821.57 IC0630 159.64 -7.170 25.85 -19.7 -23.4 2451870.67-2457821.57 ESO324-044 204.52 -39.84 34.51 -19.7 -21.8 2451870.67-2457821.57 NGC3511 165.84 -23.08 12.25 -19.6 -22.3 2451870.67-2457821.57 IC2627 167.47 -23.72 24.21 -19.6 -22.9 2451870.67-2457821.57 NGC5121 201.19 -37.68 20.8 -19.5 -23.1 2451870.67-2457821.57 NGC3936 178.08 -26.90 18.62 -19.5 -22.2 2451870.67-2457821.57 NGC3055 148.82 4.27 25.35 -19.5 -22.5 2451870.67-2457821.57 NGC3375 161.75 -9.941 28.87 -19.5 -22.5 2451870.67-2457821.57 IC3015 182.25 -31.51 24.21 -19.5 -23.1 2451870.67-2457821.57 IC2995 181.44 -27.94 16.75 -19.4 -21.8 2451870.67-2457821.57 ESO381-029 194.11 -36.37 29.54 -19.3 -22.6 2451870.67-2457821.57 ESO569-014 162.85 -19.89 24.77 -19.3 -20.9 2451870.67-2457821.57 IC0760 181.47 -29.29 25.37 -19.2 -22.6 2451870.67-2457821.57 IC3010 181.98 -30.33 25.87 -19.2 -22.8 2451870.67-2457821.57 ESO440-011 177.19 -28.29 21.88 -19.2 -18.0 2451870.67-2457821.57 NGC3673 171.30 -26.73 17.38 -19.2 -22.6 2451870.67-2457821.57 NGC3361 161.12 -11.20 24.21 -19.1 -21.8 2451870.67-2457821.57 ESO440-038 180.42 -31.70 26.65 -19.1 -22.0 2451870.67-2457821.57 UGC05347 149.31 4.5269 29.92 -19.0 -20.2 2451870.67-2457821.57 IC3005 181.80 -30.02 24.32 -19.0 -21.9 2451870.67-2457821.57 ESO440-049 181.39 -31.42 24.24 -18.9 -20.1 2451870.67-2457821.57 ESO440-027 178.35 -28.55 18.53 -18.9 -21.7 2451870.67-2457821.57 NGC3617 169.46 -26.13 25.61 -18.9 -22.2 2451870.67-2457821.57 ESO504-028 178.72 -27.25 22.24 -18.8 -20.2 2451870.67-2457821.57 ESO440-004 176.42 -28.36 22.93 -18.8 -18.4 2451870.67-2457821.57 UGC05376 150.11 3.3744 29.92 -18.8 -22.5 2451870.67-2457821.57 ESO381-038 195.02 -34.43 28.37 -18.7 -20.3 2451870.67-2457821.57 PGC032091 161.29 -10.06 27.64 -18.6 -20.1 2451870.67-2457821.57 ESO441-014 182.55 -30.07 24.67 -18.6 -19.5 2451870.67-2457821.57 IC2996 181.45 -29.97 21.88 -18.4 -20.6 2451870.67-2457821.57 PGC031979 160.90 -9.856 24.21 -18.3 -19.8 2451870.67-2457821.57 ESO441-012 182.36 -32.51 24.21 -18.2 -21.7 2451870.67-2457821.57 ESO440-037 179.82 -28.90 22.99 -18.2 -20.9 2451870.67-2457821.57 ESO324-023 201.87 -38.17 14.26 -18.2 -19.1 2451870.67-2457821.57 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21089 SUBJECT: LIGO/Virgo G275404 and G275659: SkyMapper Follow-up Observations DATE: 17/05/11 08:26:06 GMT FROM: Seo-Won Chang at ANU S.-W. Chang, A. Mller, C. A. Onken, C. Wolf (ANU) report on behalf of the SkyMapper Transient follow-up collaboration: We had carried out follow-up observations of the LIGO/Virgo G275404 and (LVC, GCN 20738) and G275697 (LVC, GCN 20763) with the SkyMapper 1.35-m telescope on the night of 2017-02-27 UTC and 2017-03-01/2017-03-05 UTC, respectively. Our imaging fields were automatically selected to encompass 60% of the probability region of the southern sky provided by LIGO collaboration at the time of the alert. The coverages of the observed fields are similar but slightly larger than the REM follow-up observations (Chile). For the first alert, we obtained 20 fields (~120 sq. degrees) at least twice in r filter. Delayed observations are due to bad sky conditions. We used our transient survey pipeline to discover candidate variable sources in difference images by implementing a machine-learning classifier (Scalzo et al. 2017). Except for candidate variable sources previously registered in the SkyMapper Transient Database (https://www.mso.anu.edu.au/skymapper/smt/), we found a new Type Ia supernova (SN 2017bzt) that was spectroscopically classified by the PESSTO collaboration: TNSname, Name, RA, DEC, Type, Redshift, Note SN 2017bzt, SMTJ13030970-3925172, 195.790404899, -39.421452087, SN Ia, 0.11, offset 2.76" from GALEXASC J130309.82-392514.3 (https://wis-tns.weizmann.ac.il/object/2017bzt). And for the G275697 alert, 40 fields (~228 sq. degrees) were observed once or twice in ri filters over two observations on 2017-03-01 and 2017-03-05 UTC. Except for candidate variable sources previously registered in the SkyMapper Transient Database, we did not see any significant transient sources from the observed fields. One known Type II Supernova detected by ATLAS on 2017-02-19 was recovered with SkyMapper (SMT17bgo): TNSname, Name, RA, DEC, Type, Redshift, Note SN 2017blh, SMTJ10521059-2747516, 163.044138303, -27.7976683704, SN II, 0.0334, discovered by ATLAS (https://wis-tns.weizmann.ac.il/object/2017blh).