//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20689 SUBJECT: LIGO/Virgo G274296: Identification of a GW Burst Candidate DATE: 17/02/17 19:43:13 GMT FROM: Peter Shawhan at U of Maryland/LSC The LIGO Scientific Collaboration and Virgo report: The CWB Burst analysis identified candidate G274296 during real-time processing of data from LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at 2017-02-17 06:05:55.050 UTC (GPS time: 1171346771.050). This circular has been sent around 13 hours after the event due to a processing issue. G274296 is an event of interest because its false alarm rate, as determined by the online analysis, is 1.7e-07 Hz or about one in 2 months, passing our alert threshold of ~0.5/month. The event's properties can be found at this URL: https://gracedb.ligo.org/events/G274296 No other GW event candidates were identified within a 300 s window before or after G274296. One sky maps are available at this time and can be retrieved from the GraceDB event page: skyprobcc_cWB.fits, an initial localization generated by cWB, distributed via GCN notice about 13 hours after the event. The morphology of the event candidate is unclear. We can’t confirm the shape as a chirp, but we can’t discard it. Updates on our analysis of this event will be sent as they become available. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20690 SUBJECT: LIGO/VIRGO G274296: AGILE-GRID preliminary analysis DATE: 17/02/18 01:21:46 GMT FROM: Francesco Verrecchia at ASDC, INAF-OAR F. Verrecchia (ASDC and INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A. Bulgarelli, A. Zoli , N. Parmiggiani (INAF/IASF-Bo), C. Pittori (ASDC and INAF/OAR), I. Donnarumma, P. Munar-Adrover, G. Piano (INAF/IAPS), F. Lucarelli (ASDC and INAF/OAR), A. Giuliani (INAF/IASF-Mi), M. Cardillo (INAF/OA-Arcetri and INAF/IAPS), F. Longo (Univ. Trieste and INFN Trieste), A. Ursi (INAF/IAPS), F. Fuschino (INAF/IASF-Bo), Y. Evangelista (INAF/IAPS), M. Marisaldi (INAF/IASF-Bo and Bergen University)(INAF/IAPS), A. Argan, G. Minervini (INAF/IAPS), M. Pilia, A. Trois (INAF/OA-Cagliari), V. Fioretti (INAF/IASF-Bo), report on behalf of the AGILE Team: In response to the LIGO/Virgo GW trigger G274296 (GCN #20689) we performed an analysis of the AGILE Gamma-Ray Imaging Detector (GRID) data on different timescales. On LIGO trigger time (T0= 2017-02-17 06:05:55.050 UT) the GRID exposure covered about 35% of the LIGO localization region that was observed with off-axis angles between 10 and 70 deg. An analysis of the data in the energy range 30 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 G274296 localization region are reported below: 1.3e-06 erg cm^-2 s^-1 for integration time of 2s, 3.0e-08 erg cm^-2 s^-1 for integration time of 100s. These measurements were obtained with AGILE observing a large portion of the sky in spinning mode. Additional analysis of AGILE data is in progress. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20692 SUBJECT: LIGO/VIRGO G274296: Fermi GBM Observations DATE: 17/02/18 04:02:40 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 41% of the LIGO cWB probability map for G274296 at event time, with much of the northern arc occulted by Earth. There is no GBM on-board trigger within 12 hours of 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 G274296. The targeted search of the GBM data ([1], [2]) also did not find a significant gamma-ray signal. This search processes time scales of 0.265 to 8.192 s within 30 s of the LIGO event. No interesting gamma-ray candidate was found within this time window. 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: 20693 SUBJECT: LIGO/Virgo G274296: REM optical/NIR observations DATE: 17/02/18 13:27:08 GMT FROM: Paolo D'Avanzo at INAF-OAB P. D'Avanzo (INAF-OAB), G. Greco (Urbino University/INFN Firenze), A. Rossi (INAF-IASF Bo), A. Melandri, D. Fugazza, S. Covino, (INAF-OAB), E. Palazzi (INAF-IAFS 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), G. Stratta (Urbino University/INFN Firenze), G. Tagliaferri (INAF-OAB), V. Testa (INAF-OAR), L . Tomasella (INAF-OAPD), S. Yang (INAF-OAPD), E. Brocato (INAF-OAR) on behalf of GRavitational Wave Inaf TeAm report: We carried out optical/NIR follow-up observations of the LIGO/Virgo GW trigger G274296 (LVC GCN Circ. 20689) with the 60-cm robotic telescope REM located at the La Silla Observatory (Chile). The observations were carried out on 2017 Feb 18 from 00:23:52 UT to 03:09:11 UT, simultaneously in the g, r, i, z and H bands. We observed nine nearby (< 20 Mpc) galaxies within the LIGO cWB probability map. The pointing sequence was generated using the GWsky script (https://github.com/ggreco77/GWsky) starting from the high probability region of the skymap and taking into account the airmass: RA(J2000) Dec(J2000) galaxy_name Distance (Mpc) 137.0445 5.9276 UGC04797 17.3 137.5837 7.0379 NGC2775 17.3 143.6863 6.4256 PGC027228 7.78 146.1825 9.6161 IC0559 7.68 148.9515 16.4139 UGC05332 16.1 151.7796 15.9838 UGC05453 12.43 137.1523 5.2914 PGC2807128 5.7 143.4337 9.7108 SDSSJ093344.10+094239.0 16.4 144.5559 7.7234 SDSSJ093813.40+074324.2 12.94 A preliminary analysis (also based on visual comparison with the available SDSS fields) reveals no obvious optical/NIR candidate counterpart in the above galaxies down to the following magnitudes: r > 20, H > 17 (AB, 3sigma UL). Further analysis is in progress. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20694 SUBJECT: LIGO/Virgo G274296: INTEGRAL search for a prompt gamma-ray counterpart DATE: 17/02/18 21:08:15 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 G274296. The satellite was pointing at RA=17:30:10.94 Dec=-25:04:47.6, 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. We investigated the SPI-ACS, IBIS/Veto, and IBIS/ISGRI light curves between -500 and +500 s from the trigger time (2017-02-17 06:05:53 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 3.8e-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 1.4e-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 35% 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: 20695 SUBJECT: LIGO/Virgo G274296: Observations of initial skymap by project Mini-GWAC of SVOM DATE: 17/02/19 01:27:15 GMT FROM: Chao Wu at NAOC J.Y. Wei (NAOC), X.H. Han (NAOC), C. WU (NAOC), N. Leroy (LAL), S. Antier (LAL), L.P. Xin (NAOC), X.M. Meng (NAOC), L. Huang (NAOC), Y. Xu (NAOC), H.B. Cai (NAOC), J. Wang (NAOC), X.M. Lu (NAOC), Y.L. Qiu (NAOC), J.S. Deng (NAOC), L. Cao (NAOC), S. Wang (NAOC), 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. Götz (CEA), C.Lachaud (APC), on behalf of the SVOM Gravitational Astronomy group report: We observed about 1200 square degree (3 sky regions) of the skymap of the advanced LIGO trigger G274296, 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 52% prior probability that these 3 regions contain the true location of the source. The coordinates of the 3 regions and observation time are list following: start-obs(UTC) end-obs(UTC) Ra Dec Camera_ID 2017-02-17 12:20:29.0 2017-02-17 13:45:04.7 10:34:48.326 +29:29:08.60 C1 2017-02-17 13:45:30.2 2017-02-17 17:12:33.6 11:58:53.431 +29:29:28.69 C1 2017-02-18 10:53:52.3 2017-02-18 12:57:00.8 09:12:10.933 +10:39:50.19 C6 The first image was taken ~6 hours 20 minutes after the event trigger. Note that the observations on Feb. 18th. have been done under poor weather conditions. The limit magnitude is ~10 mag in R band. 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: 20696 SUBJECT: LIGO/Virgo G274296: Global MASTER Net SN bright detection during GW error box inspection DATE: 17/02/19 08:19:17 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.M. Lipunov, V.Shumkov, N.Tyurina, E. Gorbovskoy, V.G. O.Gress, Kornilov, P.Balanutsa, A.Kuznetsov, M.I.Panchenko Lomonosov Moscow State University, Sternberg Astronomical Institute 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 N.M. Budnev, O. Gress, K. Ivanov Irkutsk State University V.Yurkov, Yu.Sergienko, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk MASTER OT J042250.16-820415.4 discovery - PSN in low surface brightness galaxy MASTER-OAFA (Argentina, San Huan Uni) auto-detection system discovered OT source at (RA, Dec) = 04h 22m 50.16s -82d 04m 15.4s on 2017-02-19.12023 UT during LIGO/VIRGO alert inspection (Peter Shawhan, GCN 20689) . The OT unfiltered magnitude is 15.9m (limit 20.0m). The OT is seen in 2 images. There is no minor planet at this place. We have reference image without OT on 2016-09-25 03:50:02 UT with unfiltered magnitude limit 20.0m. There is Galalaxy ESO 15-10 with offset:P d_ra 0.1E ddec 1.6N. Spectral observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/042250.16-820415.4_S0swHrk.png http://observ.pereplet.ru/images/PSN042250.1-820415.4.jpg //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20697 SUBJECT: LIGO/Virgo G274296: Global MASTER Net two OTs detection DATE: 17/02/19 08:50:42 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.M. Lipunov, P.Balanutsa, V.Shumkov, E. Gorbovskoy, N.Tyurina, V.G. O.Gress, Kornilov, A.Kuznetsov, M.I.Panchenko Lomonosov Moscow State University, Sternberg Astronomical Institute 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 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 V.Yurkov, Yu.Sergienko, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk MASTER-Tunka (Sibiriya, Baykal, -30C)detected two additional OTs during LIGO/VIRGO alert inspection (Peter Shawhan, GCN 20689; Lipunov et al., GCN 20696). MASTER OT J111410.86+383448.2 - AGN. MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 11h 14m 10.86s +38d 34m 48.2s on 2017-02-18.77808 UT. The OT unfiltered magnitude is 18.6m (limit 19.6m). The OT is seen in 2 images. There is no minor planet at this place. We have reference image without OT on 2011-04-23.66288 UT with unfiltered magnitude limit 20.2m. There is object SDSS DR10 catalogue of candidate quasars (Brescia+, 2015, 2015MNRAS.450.3893B ) Spectral observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/111410.86383448.2.png MASTER OT J104314.39+241518.4 - PSN in the SDSS galaxy with ~4 arcsec offset. MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 10h 43m 14.39s +24d 15m 18.4s on 2017-02-18.73677 UT. The OT unfiltered magnitude is 18.8m (limit 19.3m). The OT is seen in 1 image. There is no minor planet at this place. We have reference image without OT on 2011-03-30.69752 UT with unfiltered magnitude limit 20.4m. THERE is SDSS galaxy J104314.36+241522.4 in 4 arcsec from OT. Spectral observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/104314.39241518.4.png //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20698 SUBJECT: LIGO/Virgo G274296: SWASP optical imaging coverage DATE: 17/02/19 09:43:20 GMT FROM: Danny Steeghs at U of Warwick/GOTO D. Steeghs, D.Pollacco, K.Ulaczyk, R.Cutter, R.West, A.Levan (U. Warwick), D. Galloway, E.Rol, E.Thrane (Monash U.), V. Dhillon, M.Dyer, S.Littlefair, E.Daw, J.Mullaney, J.Maund (U. Sheffield), G. Ramsay (Armagh O.), P. O'Brien, R. Starling (U. Leicester) On behalf of the GOTO collaboration: We report on optical observations with the SuperWASP Exoplanet camera array on La Palma, in response to G274296 (GCN #20689). Targeted observations containing ~82% of the source location probability were performed between 20:40 UT Feb 17 2017 and 06:55 UT Feb 18 2017. Each pointing consisted of 3x30s exposures in the clear filter and fields were repeated between 17 and 51 times during that observing window. These regions were also observed immeditately preceding the GW trigger as part of a survey mode program the night before with 2x30s exposures at each position between 1:21 and 6:54 UT Feb 17 2017 as well as on Feb 18 2017 between 1:14 and 6:14 UT. Conditions were clear and stable. Typically a (5 sigma) photometric depth equivalent to V~15 was achieved per 3x30s pointing. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20699 SUBJECT: LIGO/Virgo G274296: Pan-STARRS imaging and discovery of 70 transients DATE: 17/02/19 13:56:33 GMT FROM: S. J. Smartt at Queens U Belfast K. C. Chambers (IfA), K. W. Smith (QUB), M. E. Huber (IfA), D. R. Young, S. J. Smartt, (QUB), M. Coughlin (Harvard), T.-W. Chen (MPE), L. Denneau, H. Flewelling, A. Heinze, E. Kankare (QUB), T. Lowe, E. A. Magnier (IfA), A. Rest (STScI), B. Stalder (IfA), A. S. B. Schultz, C. W. Stubbs (Harvard) J. Tonry, C. Waters, R. J. Wainscoat, H. Weiland, M. Willman (IfA), D. E. Wright (QUB) We report that we covered 501 square degrees on the first night following the release of the G274296 alert. We began taking data at 2017-02-18.29 UT (57802.29; 25hrs after the event detection). We estimate that this first night of data coverage corresponds to a probability of containing the source of 44.7%, (based on the cWB map skyprobcc_cWB.fits ; GCN 20689). Maps will be posted on GraceDB. Images were taken in the Pan-STARRS i-band filter in a series of overlapping 45s exposures, with typically 4-8 images at each position. Difference images were produced by subtracting the Pan-STARRS1 3Pi reference image from these separate 45s exposures (Chambers et al. arXiv:1612.05560, and available at http://panstarrs.stsci.edu). We reach i ~ 21 - 21.5 in the individual exposures. Using techniques discussed in Smartt et al. (2016, MNRAS, 462, 4094), we have located and vetted transients with quality filters and a machine learning algorithm on the difference images. In the following table, we give our 70 targets, sorted by magnitude. To select these targets we required a minimum of 2 detections in these sets of images. There are 10 transients in galaxies with redshifts (from SDSS DR12), and these are listed first. The rest of the transients are not obviously associated with a galaxy with a redshift. The closest transient is PS17bfl (i=21.06) 2.9" offset from 2MASX J11504136+3715422 : z=0.035, mu=35.8, D=140 Mpc, M_i = -14.8. With this relatively faint absolute magnitude, spectroscopic classification of this transient in particular is recommended. Variable sources which are likely AGN/QSOs or variable stars have, as far as possible, been removed from this transient list. We remove likely AGN/QSOs either from catalogues, SDSS DR12 spectra, or nuclear transients which are in galaxies with previous core variability seen in Pan-STARRS general survey mode. Similarly variable stars or stellar outbursts are removed through catalogue matching. The following list is composed of SN-like transients, as far as we can tell from current data. We found 10 transients which are previously known transients or supernovae found in preceding weeks or months before G274296, and we list them here for reference. Name RA DEC MJD-Disc mag(i) z Transients with host spectroscopic redshifts : PS17bda 09:30:36.08 +11:29:53.6 57802.32131 19.41 0.090 PS17bel 10:50:34.63 +30:25:30.7 57802.30825 20.09 0.116 PS17bew 11:13:30.66 +29:40:02.9 57802.38998 20.14 0.046 PS17bdt 10:17:28.88 +22:24:57.4 57802.30240 20.26 0.048 PS17bfg 11:45:39.79 +33:23:38.9 57802.41584 20.67 0.141 PS17bdr 10:11:35.41 +19:15:46.7 57802.30099 20.74 0.078 PS17bfy 12:06:57.57 +35:25:36.9 57802.40619 21.01 0.081 PS17bfl 11:50:41.38 +37:15:45.0 57802.40490 21.06 0.035 PS17bdz 10:27:42.90 +28:21:20.3 57802.30500 21.06 0.161 PS17bef 10:38:13.94 +25:49:24.6 57802.30435 21.19 0.078 Transients with no host spectroscopic redshifts : PS17bgn 11:31:52.98 +29:59:45.1 57802.41391 18.33 bright nuclear transient PS17bfc 11:29:33.54 +34:12:07.1 57802.39565 19.42 PS17beo 10:53:24.67 +28:51:27.1 57802.30825 19.51 PS17bgt 11:58:09.80 +34:04:38.0 57802.40426 19.81 PS17bek 10:47:41.90 +26:50:06.0 57802.30629 19.85 PS17bcv 09:16:27.70 +03:35:25.1 57802.28975 19.90 PS17bgf 10:59:22.27 +29:44:11.3 57802.41064 19.91 PS17bed 10:31:52.14 +24:26:31.0 57802.35657 20.10 PS17bep 10:57:33.56 +31:05:16.0 57802.42273 20.17 PS17bdv 10:21:15.87 +23:38:53.3 57802.30370 20.23 PS17bem 10:51:31.88 +26:29:10.4 57802.30760 20.29 PS17bgm 11:28:24.06 +30:06:26.5 57802.39965 20.31 PS17bgx 09:20:37.00 +12:53:17.8 57802.48646 20.37 PS17bgz 10:29:39.67 +26:38:57.9 57802.43359 20.45 PS17bdm 10:05:41.12 +22:31:24.9 57802.35248 20.47 PS17bev 11:11:17.74 +31:28:53.4 57802.39824 20.57 PS17bfh 11:46:47.23 +31:34:13.4 57802.40169 20.63 PS17bcs 09:02:44.47 +02:12:41.1 57802.44885 20.65 PS17bdn 10:05:43.77 +22:31:05.8 57802.29958 20.66 PS17bff 11:42:16.34 +32:36:01.9 57802.40169 20.70 PS17bgu 12:04:37.88 +32:07:42.4 57802.31211 20.74 PS17bgp 11:42:27.80 +31:02:12.5 57802.40169 20.74 PS17bfm 11:55:15.38 +35:50:48.6 57802.40490 20.80 PS17beg 10:40:17.22 +27:47:37.2 57802.30629 20.82 PS17bgr 11:47:04.86 +35:13:14.0 57802.40490 20.85 PS17bgd 10:28:30.41 +22:30:23.2 57802.30370 20.90 PS17beh 10:42:02.04 +29:51:18.1 57802.30564 20.97 PS17bgs 11:55:32.52 +29:55:29.7 57802.40362 20.99 PS17bgo 11:33:14.22 +30:53:06.1 57802.39965 21.02 PS17bdx 10:22:58.46 +24:38:17.0 57802.35590 21.02 PS17bgc 10:22:36.15 +21:12:37.9 57802.30163 21.03 PS17bgw 12:09:21.73 +36:46:08.2 57802.40619 21.05 PS17beb 10:31:19.80 +26:56:54.5 57802.33322 21.05 PS17bcx 09:24:03.25 +08:04:33.8 57802.34338 21.05 PS17bgi 11:12:46.03 +28:38:50.4 57802.41131 21.10 PS17bfz 09:16:10.00 +08:37:10.4 57802.45144 21.12 PS17bdu 10:20:34.54 +20:12:51.4 57802.30163 21.13 PS17bgb 09:46:52.25 +10:39:51.1 57802.29491 21.13 PS17bei 10:42:41.75 +25:35:06.8 57802.35990 21.15 PS17bdw 10:22:57.59 +24:38:22.1 57802.38244 21.15 PS17bdb 09:32:00.94 +15:00:40.2 57802.29362 21.16 PS17bcu 09:15:24.05 +03:45:37.4 57802.34263 21.16 PS17bee 10:34:00.57 +26:56:00.3 57802.35723 21.17 PS17bfk 11:50:33.88 +35:33:45.1 57802.40490 21.19 PS17bge 10:57:22.95 +30:22:03.4 57802.38805 21.19 PS17bfo 11:57:44.78 +32:54:59.9 57802.39192 21.20 PS17bgq 11:43:47.66 +32:44:07.0 57802.40169 21.21 PS17bgg 11:03:12.23 +31:56:23.9 57802.33709 21.21 PS17bgl 11:24:07.20 +36:13:14.2 57802.40233 21.36 PS17bds 10:16:57.14 +24:34:18.8 57802.30240 21.40 PS17bfb 11:24:05.27 +33:26:57.0 57802.40105 21.42 PS17bgh 11:12:08.04 +30:21:11.1 57802.38998 21.45 PS17bet 11:08:34.19 +30:03:46.3 57802.38934 21.46 PS17bgy 09:32:17.63 +13:36:14.5 57802.48711 21.50 PS17bgv 12:08:20.09 +38:45:20.8 57802.40554 21.53 PS17bdl 10:04:29.91 +22:01:20.9 57802.32850 21.54 PS17bgk 11:15:17.75 +30:53:09.5 57802.42537 21.57 PS17bgj 11:15:16.28 +32:14:05.4 57802.39062 21.64 PS17bga 09:16:19.41 +00:47:06.0 57802.44950 21.69 PS17bfe 11:41:34.79 +30:39:15.2 57802.40169 21.73 Already known objects : PS17bhc 09:47:26.75 +19:36:31.1 57789.49854 21.00 PS17bhb 09:44:33.28 +15:15:42.4 57789.50327 21.61 PS17bha 09:27:42.08 +12:00:14.1 57789.47490 20.78 PS17beu 11:10:52.80 +28:16:27.8 57802.30954 19.18 AT2017nf PS17bfw 12:01:07.05 +38:52:35.0 57802.40554 20.66 CSS160514-120107+385236 PS17abg 10:50:24.61 +23:59:21.5 57802.35990 21.24 AT2017qh PS17bdp 10:06:29.10 +22:26:43.9 57802.32850 16.89 SN2016idl PS17gn 10:01:11.46 +19:29:43.2 57802.29814 20.91 AT2016ieg PS17bdj 10:00:18.25 +19:23:05.1 57802.29814 19.85 MLS160217-100018+192305 PS17m 09:34:55.90 +06:17:27.0 57802.29169 20.01 AT2017D //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20700 SUBJECT: LIGO/Virgo G274296: CNEOST imaging coverage and an optical transient DATE: 17/02/19 14:26:03 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 G274296 (LVC, GCN 20689) using the 1-m Chinese Near Earth Object Survey Telescope (CNEOST) at Xuyi, Jiangsu, and the 0.6/0.9-m Schmidt telescope at Xinglong, Hebei, China. CNEOST has a FOV of 3.0x3.0 deg^2, and covered ~1400 square degrees from 10:40:00.05 UT to 22:01:49.81 UT on 2017-02-18 in the Sloan r-filter. The skymap coverage is at https://dl.dropboxusercontent.com/u/3665676/G274296/skymap20170218NEOST.pdf and the typical limiting magnitude is m(r)~20.0. Preliminary analysis from our vetting procedure reveals several supernova (SN) candidates and quite a few AGN candidates. Most SN candidates were already reported by different surveys days before the G274296 trigger time (i.e., 06:05:55.05 UT on 2017-02-17). We here note one SN candidate discovered after the GW trigger time, dubbed as PTSS-17gpm and observed at 19:01:33 UT, at coordinates: R.A. (J2000) = 11:59:59.45 Dec. (J2000) = +31:57:46.98 with m(r)~18.6. It was also discovered by the ATLAS project, dubbed as AT 2017axh or ATLAS17bbz and discovered by on 12:48:57 on 2017-02-17. This source is positionally coincident with the galaxy SDSS J115959.38+315745.7, which has m(r)=19.47 and a PhotoZ=0.09+/-0.04. Further observations are planned. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20701 SUBJECT: LIGO/Virgo G274296: Optical Observation DATE: 17/02/19 15:04:19 GMT FROM: Myungshin Im at Seoul National U M. Im, S. Lee, C. Choi, G. Lim, S. Hwang, H. M. Lee (SNU), S. Pak, T.-G. Ji (KHU), H.-I. Sung (KASI), S. Ehgamberdiev (UBAI) on behalf of the KU collaboration We observed a 49 square degree of the probability area of G274296 using a wide-field 0.25m telescope (a piggyback system on the 0.8m telescope) at the McDonald observatory, Texas, USA. The observation was performed in R-band, starting at 2017-02-18 11:27 (UT). A preliminary analysis of the data shows the detection limit of R ~ 17.8 mag at 5-sigma for a point source detection. The covered fields are indicated below, each having a 2.35 deg x 2.35 deg field of view centered at the coordinates. The central parts of the fields are covered by the 0.8m telescope simultaneously, covering 46.2 arcmin x 46.2 arcmin field of view to the depths about 0.7 magnitude deeper than the 0.25m data. The analysis of the data is ongoing. Field RA Dec G1: 12:10:00.00 40:30:00.0 G2: 12:10:00.00 38:00:00.0 G3: 12:10:00.00 35:30:00.0 G4: 12:20:00.00 40:30:00.0 G5: 12:20:00.00 38:00:00.0 G6: 12:20:00.00 35:30:00.0 G7: 12:30:00.00 40:30:00.0 G8: 12:30:00.00 38:00:00.0 G9: 12:30:00.00 35:30:00.0 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20704 SUBJECT: LIGO/Virgo G274296 ANTARES search DATE: 17/02/19 18:15:44 GMT FROM: Damien Dornic at CPPM/CNRS M. Ageron (CPPM/CNRS), B. Baret (APC/CNRS), A. Coleiro (APC/Universite Paris Diderot), D. Dornic (CPPM/CNRS), A. Kouchner (APC/Universite Paris Diderot), T. Pradier (IPHC/Universite de Strasbourg) report on behalf of the ANTARES Collaboration: Using on-line data from the ANTARES detector, we have performed a follow-up analysis of the recently reported LIGO/Virgo G274296 event using the initial LIGO skyprobcc_cWB probability map at event time (LVC GCN Circ. 20689). 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/G274296.png (gwantares/ANT@GW). Considering the location probability provided by the LIGO collaboration, there is a 34% chance that the GW emitter was in the ANTARES field of view. ANTARES, being installed in the Mediterranean Deep Sea, is the largest neutrino detector in the Northern Hemisphere. It is primarily sensitive to astrophysical neutrinos in the TeV-PeV energy range. At 10 TeV, the median angular resolution for muon neutrinos is below 0.5 degrees. In the range 1-100 TeV, ANTARES has the best sensitivity to a large fraction of the Southern sky. No up-going muon neutrino candidate events were recorded within the 90% contour during a +/- 500s time-window centered on the G274296 event time. The expected number of atmospheric background events in the 90% contour region visible by ANTARES is ~5.4e-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. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20705 SUBJECT: LIGO/Virgo G274296: AstroSat CZTI upper limits DATE: 17/02/19 19:29:17 GMT FROM: Varun Bhalerao at IUCAA 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 G274296 trigger time, UT 2017-02-17 06:05:55.050, 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 LIB skymap provided by LVC (skyprobcc_cWB.fits,0), the sky visible to CZTI has 6.3% 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 band function parameters, with alpha = -1, beta = -2.5 ans E_peak = 300 keV. The sensitivity of CZTI varies with direction. We weight the sensitivity by the CWB 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 1.8e-07 ergs/cm^2, 4.4e-07 ergs/cm^2 and 1.1e-06 ergs/cm^2 for search timescales of 0.1, 1, and 10 seconds respectively. The corresponding flux upper limits for the three timescales are 1.8e-06, 4.4e-07, and 1.1e-07 ergs/cm^2/sec respectively. Plots showing CZTI sensitivity as a function of direction can be found at https://gracedb.ligo.org/apiweb/events/G274296/files/G274296_CZTI_limits.pdf,0 About 30% of the localisation region had emerged from earth occultation 2200 seconds after the trigger. Searching the data from T+2200s to T+3200s for transients with 10s duration, we do not find any significant transient candidate above background noise. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20707 SUBJECT: LIGO/Virgo G274296: Fermi-LAT search for a high-energy gamma-ray counterpart DATE: 17/02/19 21:37:18 GMT FROM: Nicola Omodei at Stanford U Nicola Omodei (Stanford), Giacomo Vianello (Stanford), Daniel Kocevski (NASA/MSFC) and Sara Buson (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 G274296. The region of the LIGO map with probability >90% entered the LAT field of view at T0+400 (T0 = 2017-02-17 06:05:53 UTC), and reached full coverage at about 7ks from T0. We searched for a transient counterpart within the LIGO 90% probability contour in the time window from T0 to T0 + 10 ks and found no significant new sources. We also performed a search that adapted the time interval of the analysis to the exposure of each region of the sky. No significant candidate counterpart was found. 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: 20708 SUBJECT: LIGO/Virgo G274296: PESSTO classification of 9 Pan-STARRS transients DATE: 17/02/20 12:59:08 GMT FROM: S. J. Smartt at Queens U Belfast F. Taddia, C. Barbarino, A. Nyholm, C. Fremling, J. Sollerman (OKC), M. T. Botticella (INAF-Capodimonte), M. Fraser (UCD), C. Inserra, E. Kankare, K. Maguire, S. J. Smartt, K. W. Smith, D. Wright, D. Young (QUB), M. Sullivan (Southampton), S. Valenti (UC Davis), O. Yaron, I. Manulis (Weizmann), E. Cappellaro (INAF-Padova), K. C. Chambers (IfA), M. E. Huber (IfA), M. Coughlin (Harvard), T.-W. Chen (MPE), L. Denneau, H. Flewelling, A. Heinze, T. Lowe, E. A. Magnier (IfA), A. Rest (STScI), B. Stalder, A. S. B. Schultz (IfA), C. W. Stubbs (Harvard) J. Tonry, C. Waters, R. J. Wainscoat, H. Weiland, M. Willman (IfA) PESSTO, the Public ESO Spectroscopic Survey for Transient Objects (see Smartt et al. 2015, A&A, 579, 40 http://www.pessto.org), reports the following supernova classifications related to G274296 within the cWB map skyprobcc_cWB.fits (GCN 20689). Targets were supplied by Pan-STARRS as in Chambers et al. (GCN20699). For Pan-STARRS information, see Chambers et al. 2016 (arXiv:1612.05560, and http://pswww.ifa.hawaii.edu). We selected targets brighter than i=20.5 and accessible from La Silla. All observations were performed on the ESO New Technology Telescope at La Silla on 2017 February 19, using EFOSC2 and Grism 13 (3985-9315A, 18A resolution). Classifications were done with SNID (Blondin & Tonry, 2007, ApJ, 666, 1024) and GELATO (Harutyunyan et al., 2008, A&A, 488, 383). Classification spectra and additional details can be obtained from http://www.pessto.org (via WISeREP). Name RA (J2000) Dec (J2000) Disc. Date Disc Mag z Type Phase Notes PS17bcv 09 16 27.70 +03 35 25.2 20170218 19.9 0.104 IIn ? (1) PS17bda 09 30 36.08 +11 29 53.6 20170218 19.4 0.090 Ia -3 to +3 d (2) PS17bgx 09 20 37.01 +12 53 17.8 20170218 20.4 ? ? ? (3) PS17bdt 10 17 28.88 +22 24 57.5 20170218 20.3 0.048 II +12 d (4) PS17bdv 10 21 15.88 +23 38 53.2 20120218 20.4 0.14 Ia +8 to +10 d (5) PS17bel 10 50 34.64 +30 25 30.7 20120218 20.0 0.116 Ia +4 to +7 d (6) PS17beo 10 53 24.68 +28 51 27.1 20120218 19.6 0.217 IIn +30 d (7) PS17bgn 11 31 52.98 +29 59 45.1 20120218 18.3 0.148 SLSN II >+50d (8) PS17bek 10 47 41.90 +26 50 06.0 20120218 19.7 0 Stellar - (9) Notes (1) Narrow Halpha and Hbeta in emission. Offset from the host-galaxy center. (2) Best SNID matches to several 1991T-like SNe Ia before and around maximum. Redshift from SDSS. (3) Blue featureless spectrum. (4) Best SNID fit to SN 2004et at +12 d. Other good fits with SNe II at +0 d and +20 d. Redshift from SDSS. (5) Best SNID match with normal SN Ia 2002dj at +9 d. Several other good matches with normal SNe Ia at similar age. (6) Best SNID match with several normal SNe Ia at +4 to +7 d. Redshift from SDSS. (7) Good GELATO match to SN IIn 2010jl at +28 d. Absolute magnitude -20.2 mag. (8) Redshift and phase based on the best SNID match to SN IIL 1979C. Broad double-peaked Halpha and Hbeta, similar to nebular type II spectra. Absolute magnitude -20.8 mag, very bright for inferred phase. (9) Narrow Halpha detection at z=0. Blue spectrum with black body temperature of about 10000 K. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20709 SUBJECT: LIGO/Virgo G274296: IceCube neutrino observations DATE: 17/02/20 21:46:28 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 G274296. We compared the candidate source directions of 3 temporally-coincident neutrinos to the cWB skymap, with the following parameters: # dt[s] RA[deg] Dec[deg] E[TeV] Sigma[deg] -------------------------------------------- 1. -279 136.6 20.8 9.55 1.7 2. -134 299.3 14.3 10.53 0.6 3. 228 9.8 7.7 5.36 0.4 The analysis found NO COINCIDENT ONLINE TRACK-LIKE NEUTRINO CANDIDATES detected by IceCube within the 500 second window surrounding G274296 within the cWB skymap. In addition, we performed 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. NO COINCIDENT HESE OR SUPERNOVA SIGNATURES were identified by these searches. 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: 20711 SUBJECT: LIGO/Virgo G274296: PSN MASTER OT J042250.16-820415.4 is before maximum DATE: 17/02/21 12:46:23 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.M. Lipunov, V.Shumkov, N.Tyurina, E. Gorbovskoy, V.G.Kornilov, P.Balanutsa, A.Kuznetsov, A.V. Krylov, I. Gorbunov, M.I.Panchenko Lomonosov Moscow State University, Sternberg Astronomical Institute D.Buckley, S. Potter, M. Kotze, South African Astronomical Observatory 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 N.M. Budnev, O. Gress, K. Ivanov Irkutsk State University V.Yurkov, Yu.Sergienko, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk MASTER-SAAO reobserved PSN MASTER OT J042250.16-820415.4, discovered on 2017-02-19.12023UT (Lipunov et al., GCN 20696) in W,BVRI . This PSN arises, so it has possibility to explode on the 17th of Feb 2017 (Peter Shawhan, GCN 20689) . Preliminary photometry is the following: Date UT mag 2017-02-19 02:37:46 UT W=16.3 (discovery date) 2017-02-19 19:25:59 UT W=16.2 2017-02-20 19:23:54 UT W=15.7 2017-02-20 18:43:57 UT V=16.0 2017-02-20 19:07:59 UT I=15.9 2017-02-20 19:07:59 UT R=16.0 The spectroscopy observations are required its age and type determination. Light curve is available at http://master.sai.msu.ru/static/OT/MASTEROTJ04225016-8204154.jpg //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20712 SUBJECT: LIGO/Virgo G274296: MASTER new bright possible SN detection and inspection dinamic DATE: 17/02/21 14:03:05 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.M. Lipunov, E. Gorbovskoy, N.Tyurina, P.Balanutsa, V.Shumkov, 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 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 V.Yurkov, Yu.Sergienko, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk MASTER continues inspection of LIGO event G274296 (Shawhan et al. GCN20689, Lipunov et al. GCN20696). The cover map of MASTER inspection survey, the position of MASTER OTs inside LIGO error-box is presented at http://master.sai.msu.ru/static/MASTERGW170217full.jpg MASTER OT J105519.53+365834.1 - bright PSN in 1.2"E,1.2"S from the center of PGC032819 (Sc type http://leda.univ-lyon1.fr/ledacat.cgi?PGC032819 ) MASTER-Tunka (Near Baykal, Irkutsk, Russia) auto-detection system discovered optical transient at RA(2000)=10h 55m 19.53s +36d 58m 34.1s on 2017-02-18 18:18:18UT with unfiltered m_OT=15.7 (MASTER W=0.2B+0.8R calibrated by USNO-B1 thousands stars in the field). This PSN is seen on 3 images and is located in 1.2"E,1.2"S from the center of spiral PGC032819 . We have reference images without OT on 2016-01-01 21:12:22 with mlim=19.9, on 2016-12-25 21:56:41UT with mlim=18.8. Spectral observatios are required. The discovery and reference images are http://master.sai.msu.ru/static/OT/MASTEROTJ105519.53+365834.1.jpg //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20713 SUBJECT: LIGO/Virgo G274296: ATLAS confirmation of the bright MASTER transient and earlier explosion date DATE: 17/02/21 15:14:53 GMT FROM: S. J. Smartt at Queens U Belfast S. J. Smartt, K. W. Smith, D. R. Young, (QUB), J. Tonry, L. Denneau, A. Heinze, B. Stalder, H. Weiland (IfA), C. W. Stubbs (Harvard), A. Rest (STScI), K. C. Chambers (IfA), T.-W. Chen (MPE), M. Coughlin (Harvard), M. E. Huber (IfA), D. E. Wright (QUB), H. Flewelling, T. Lowe, E. A. Magnier, A. S. B. Schultz, C. Waters, R. J. Wainscoat, M. Willman (IfA) Lipunov et al. (GCN 20712) reported the discovery of a very bright, mag=15.7 transient in the sky localisation map of G274296 (GCN20689) at the position : MASTER OT J105519.53+365834.1 RA(2000)=10h 55m 19.53s +36d 58m 34.1s at 2017-02-18 18:18:18 UT (MJD=57802.76271) and close to (within 1.7”) of the centre of an edge-on spiral galaxy at z = 0.043224 (KUG 1052+372; PGC 032819) With the ATLAS telescope system (see Tonry et al. GCN 20382 and www.fallingstar.com), we confirm the reality of this bright transient, however it exploded well before the GW detection G274296. The MJD of the GW source was 57801.2541094 as announced in GCN20689. In ATLAS routine survey mode we detect the transient (internally called ATLAS17bbp) on two images on the night of MJD=57794 at mag = 18.23 (orange filter) and again on 5 images on each of 57798 and 57802, the latest with m=17.40 +/- 0.07 (the orange bandpass is approximately equivalent to o ~ 0.56r+0.44i). The difference in the magnitudes between ATLAS and MASTER is likely due to ATLAS performing difference imaging photometry and the transient being located close to the galaxy core. The ATLAS17bbp coordinates are RA=163.83115 DEC=+36.97640 (10:55:19.47 +36:58:35.0) While this is certainly real, and within the LIGO localisation banana, it has an explosion date at least 7 days before G274296. We measure a 1.2" difference in the astrometric coordinates of PGC 032819 and ATLAS17bbp, but further analysis is required to determine if it actually is coincident with the galaxy nucleus. The source fell outside the northern egde of the Pan-STARRS1 coverage (Chambers et al. GCN 20699). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20714 SUBJECT: LIGO/Virgo G274296: Asiago 1.82m Optical Observations DATE: 17/02/21 15:22:15 GMT FROM: Enzo Brocato at INAF-OA Roma L. Tomasella, E. Cappellaro (INAF OAPd), G. Greco (Urbino University/INFN Firenze), A. Rossi, E. Palazzi (INAF-IASF Bo), M. Branchesi (Urbino University/INFN Firenze), L. Amati (INAF-IASF Bo), L. A. Antonelli, S. Ascenzi (INAF-OAR), M.T. Botticella (INAF-OAC), S. Campana, S. Covino, P. D'Avanzo (INAF-OAB), V. D'Elia (INAF-ASDC), F. Getman, A. Grado, L. Limatola (INAF-OAC), M. Lisi (INAF-OAR), A. Melandri (INAF-OAB), L. Nicastro (INAF-IASF Bo), E. Pian (SNS-Pisa), S. Piranomonte, L. Pulone (INAF-OAR), G. Stratta (Urbino University/INFN Firenze), G. Tagliaferri (INAF-OAB), V. Testa (INAF-OAR), S. Yang (INAF-OAPD), E. Brocato (INAF-OAR) on behalf of GRavitational Wave Inaf TeAm (GRAWITA) report: We carried out optical follow-up observations of the LIGO/Virgo GW trigger G274296 (LVC GCN Circ. 20689) with the Copernico 1.82m telescope (INAF OAPd, Asiago-Ekar, Italy). The observations were carried out starting on 2017 Feb 17 from 20:56:11.7 UT, until 2017 Feb 18, 03:22:58.5 UT, using Sloan g-band. We observed several nearby (< 20 Mpc) galaxies within the LIGO cWB probability map. The pointing sequence was generated using the GWsky script (https://github.com/ggreco77/GWsky ) starting from the high probability region (30%) of the skymap (with the exception of the first three follow-up observations in the field of NGC4096, after GCN 20688) and taking into account the airmass: p01 12:06:00.60 +47:28:39 NGC4096 (follow-up after GCN 20688) p02 12:06:00.59 +47:28:45 NGC4096 (follow-up after GCN 20688) p03 12:06:00.55 +47:39:59 Norther of NGC4096 (GCN 20688) p04 10:51:20.65 +32:46:00 NGC3413 p05 10:56:19.93 +31:16:10 2MASX J10562004+3116126 p06 10:12:53.15 +22:43:15 MCG+04-24-018 p07 10:32:17.28 +27:40:10 NGC3274 p08 11:52:55.65 +36:59:16 NGC3941 p09 11:51:45.69 +38:00:55 NGC3930 p10 10:11:08.79 +23:52:31 LEDA 1695322 p11 10:17:39.63 +22:48:33 2MASX J10173965+2248358 p12 10:11:16.68 +24:03:56 AGC 721972 p13 09:21:00.10 +11:03:39 LEDA 26453 p14 09:21:00.12 +11:03:39 LEDA 26453 p15 09:21:01.14 +11:03:39 LEDA 26453 p16 09:55:48.15 +16:24:48 UGC5332 p17 10:31:48.30 +25:18:26 SDSS J103149.00+251816.0 p18 11:58:29.99 +38:04:34 UGC6955 p19 10:10:33.29 +22:00:36 LEDA 139255 p20 10:27:13.83 +24:09:44 LEDA 1701087 p21 10:23:44.64 +27:06:44 LEDA 1798058 p22 10:31:56.20 +28:01:37 LEDA 1824266 p23 12:03:53.89 +38:54:11 LEDA 2139249 p24 09:14:58.10 +06:00:17 SDSS J091457.31+060016.7 p25 10:27:16.93 +28:30:42 SDSS J102716.85+283039.6 p26 10:24:14.30 +24:25:46 AGC 731449 p27 10:32:18.79 +27:39:57 SDSS J103217.21+274007.7 p28 10:35:11.18 +25:27:00 SDSS J103511.05+252704.0 p29 10:28:58.61 +25:17:07 AGC 731454 p30 10:20:00.21 +24:25:55 SDSS J102002.81+242615.0 p31 10:19:59.99 +24:47:32 SDSS J101959.88+244724.6 p32 09:58:17.18 +21:05:19 SDSS J095816.17+210520.4 p33 09:33:44.60 +09:42:35 SDSS J093344.10+094239.0 p34 09:21:15.41 +09:42:55 SDSS J092114.97+094352.2 p35 09:29:51.95 +11:55:41 SDSS J092951.83+115535.7 The upper limit of the measured g-band magnitudes is 20.5-21.0 (AB mag, 3sigma). Based on comparison with SDSS field templates we detected a SN candidate at RA=10:27:28.025, Dec=+24:12:45.85 with magnitude g = 19.31 +/- 0.05 mag (AB). The object is hosted in a faint field galaxy SDSS J102727.87+241249.9, with photometric redshift photoZ=0.074 (SDSS DR13). Assuming the above redshift, the absolute magnitude is around -18.3. Few other transients are likely faint variable stars, since they are already visible in the SDSS images. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20715 SUBJECT: LIGO/Virgo G274296: Global MASTER Net PSN and QSO detection DATE: 17/02/21 23:08:53 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.M. Lipunov, E. Gorbovskoy, T.Pogrosheva, N.Tyurina, P.Balanutsa, V.Shumkov, V. 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 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 V.Yurkov, Yu.Sergienko, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk During inspection of LIGO event G274296 (Shawhan et al. GCN20689, Lipunov et al. GCN20696, GCN20712) MASTER-Tunka detected the following additional optical transients: 1) MASTER OT J144935.82+343749.9 discovery - PSN (18.0m) in SDSS galaxy(r=20.9) During GW inspection survey MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 14h 49m 35.82s +34d 37m 49.9s on 2017-02-21.77409UT. The OT unfiltered magnitude is 18.0m (mlimit 19.4m). The OT is seen in 2 images. There is no minor planet at this place. There is SDSS galaxy with red m=20.94 http://skyserver.sdss.org/dr9/en/tools/quicklook/quickobj.asp?id=1237662226228118204 We have reference image without OT on 2016-12-05.94591 UT with unfiltered magnitude limit m=20.0m. Spectral observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/144935.82343749.9.png MASTER OT J082950.02+274024.3 - possibly QSO outburst During GW inspection survey MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 08h 29m 50.02s +27d 40m 24.3s on 2017-02-21.56417 UT. The OT unfiltered magnitude is 19.1m (limit 20.1m). The OT is seen in 3 images. There is no minor planet at this place. We have reference image without OT on 2015-11-19.71169 UT with unfiltered magnitude limit m=20.1m. There is GALEX source in 0.8" and this OT is in 1" from SDSS DR10 catalogue of candidate quasars (Brescia+, 2015), i.e. our OT is QSO in outburst. Spectral observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/082950.02274024.3.png //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20716 SUBJECT: LIGO/Virgo G274296: Kanata 1.5m optical spectroscopy of MASTER optical transient DATE: 17/02/22 00:37:01 GMT FROM: Michitoshi Yoshida at J-GEM T. Nakaoka, T. Abe, M. Chogi, M. Yoshida, Y. Utsumi and K. S. Kaawbata (Hiroshima University) on behalfof J-GEM collaboration, We performed optical spectroscopy of the optical transient MASTER OT J105519.53+365834.1PSN in PGC 032819 (Lipunov et al. GCN 20712) with 1.5-m Kanata telescope at Higashi-Hiroshima Observatory on 2017 Feb 21. The spectrum shows a broad absorption line around 620 nm. The overall features suggest that this PSN is a SN 1991T like bright Type Ia supernova around maximum brightness. A comparison with a library of supernova spectra using GELATO (Harutyunyan et al. 2008, A.Ap. 488, 383) suggests that the spectrum gives a good match to SN 1998es at -3.5 days before B-band maximum. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20717 SUBJECT: LIGO/Virgo G274296: iPTF Optical Transient Candidates DATE: 17/02/22 01:11:33 GMT FROM: Mansi M. Kasliwal at Caltech R. Ferretti (OKC), R. Lunnan (Caltech), M. M. Kasliwal (Caltech), L. P. Singer (NASA/GSFC), S. B. Cenko (NASA/GSFC), D. Cook (Caltech), C. Cannella (Caltech), A. van Sistine (UWM), T. Barlow (Caltech), V. Bhalerao (IUCAA), J. Rana (IUCAA), A. A. Miller (Northwestern/Adler), Y. Cao (UW) 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 G274296 (LVC, GCN 20689) using the Palomar 48-inch Oschin telescope (P48) on the night of 2017-02-21 UTC. We imaged 111 fields spanning 807 square degrees, with a 54% chance of containing the true location of the source. Of these, 69 fields (502 square degrees; 42% probability) were imaged twice and searched for transient candidates. During preliminary sifting through candidate variable sources using image subtraction by our IPAC pipeline (Masci et al. 2016), and applying standard iPTF vetting procedures, we flagged the following optical transient candidates (60 total) for further follow-up: name RA Dec time mag z notes -------- ---------- ---------- ----- ----- ------ --------- iPTF17bed 234.991732 +34.088243 2457806.0160 20.17 0.138 photz; at edge of galaxy iPTF17bec 232.665446 +33.928645 2457806.0160 19.90 0.0482 specz; irregular galaxy; fading (0.34 mag intra-night) iPTF17beb 235.828735 +32.682827 2457806.01757 19.03 0.07 photz iPTF17bdz 174.715936 +33.828372 2457805.90013 20.05 0.0327 specz; nuclear edge-on iPTF17bdy 178.129375 +35.456339 2457805.90162 20.30 0.0943 specz; slightly off-center iPTF17bdw 178.329915 +36.442293 2457805.90313 20.29 0.18 photz iPTF17bds 183.323594 +39.266026 2457805.9061 20.11 0.13 photz; fading (0.40 mag intra-night) iPTF17bdq 181.290430 +37.270222 2457805.90762 19.94 0.0226 specz iPTF17bdp 182.529730 +36.393440 2457805.90762 20.08 0.2432 specz; nuclear (SDSS QSO) iPTF17bdn 184.075520 +40.796273 2457805.93462 20.57 0.136 photz iPTF17bdl 183.608407 +42.063649 2457805.9346 19.65 0.0231 specz; nuclear? iPTF17bdk 186.611638 +40.726698 2457805.9346 20.55 0.0699 specz; nuclear? iPTF17bdj 185.368397 +42.208415 2457805.93462 19.51 0.1206 specz iPTF17bdf 188.315478 +36.824458 2457805.93763 19.68 0.095 photz iPTF17bde 187.281321 +36.457123 2457805.93763 19.58 0.0714 specz; slightly off-center iPTF17bdd 191.013043 +41.168996 2457805.93912 19.04 0.0237 specz; nuclear?; rising (0.48 mag intra-night) iPTF17bdc 192.553197 +36.464676 2457805.9421 20.49 0.1448 specz; at edge of galaxy iPTF17bda 193.915287 +39.855467 2457805.9436 19.21 0.38 photz iPTF17bcz 196.354965 +39.004452 2457805.9436 19.59 0.0808 specz; off-center iPTF17bcy 197.058084 +41.600850 2457805.9466 20.23 0.0272 specz iPTF17bcw 201.468624 +39.173964 2457805.94814 20.65 0.0636 specz iPTF17bcs 198.456906 +38.894402 2457805.94814 19.60 0.0794 spez; nuclear iPTF17bcr 200.757880 +40.201309 2457805.9481 20.35 0.0640 specz iPTF17bcn 201.030920 +42.445651 2457805.95116 19.99 0.079 photz; nuclear iPTF17bcl 207.110772 +41.975701 2457805.95416 20.44 0.183 photz iPTF17bck 208.258285 +40.302280 2457805.95715 19.85 ? no photz available iPTF17bci 209.602490 +43.662936 2457805.95867 19.74 0.065 specz; nuclear iPTF17bch 209.362268 +44.387701 2457805.95867 19.65 0.072 specz; nuclear? iPTF17bcg 211.528986 +42.673631 2457805.96015 19.37 0.088 specz iPTF17bce 212.679949 +37.081015 2457805.96316 20.37 0.224 photz iPTF17bbv 174.674325 +36.232952 2457805.8986 18.27 0.05996 specz iPTF17bbu 167.125966 +31.440313 2457805.8911 19.70 0.06 photz iPTF17bbt 166.948991 +31.255977 2457805.8911 20.02 0.087 photz iPTF17bbs 166.950771 +31.311975 2457805.8911 19.95 0.072 specz iPTF17bbq 168.377846 +29.667545 2457805.8911 20.25 0.0455 specz; =PS17bew (GCN 20699) iPTF17bbp 166.537702 +30.246383 2457805.8911 19.95 0.030 specz iPTF17bbn 167.184990 +31.218324 2457805.8911 19.29 0.073 specz; also detected 2017-02-17 (g=20.11); nuclear iPTF17bbg 169.748759 +35.743451 2457805.89411 19.89 0.104 specz iPTF17bbf 170.901072 +34.765936 2457805.89411 19.60 0.186 photz iPTF17bbe 170.036330 +34.312810 2457805.89411 20.49 0.037 specz; nuclear (SDSS AGN) iPTF17bbb 170.475973 +33.961040 2457805.89411 20.11 0.078 photz iPTF17bba 170.464827 +33.845571 2457805.89411 19.88 0.044 specz iPTF17baz 170.427019 +34.363034 2457805.89411 19.05 0.035 specz iPTF17bav 168.441386 +37.278479 2457805.8956 19.61 0.100 specz iPTF17bat 171.393094 +40.511821 2457805.89712 20.01 0.122 specz iPTF17baq 134.698013 +01.842508 2457805.78102 19.70 0.058 specz; nuclear? iPTF17bap 134.438423 +00.933616 2457805.78102 19.80 0.120 specz; nuclear iPTF17bao 133.976313 +00.853143 2457805.78102 19.41 0.053 specz; nuclear (SDSS AGN) iPTF17bam 134.670596 +02.078209 2457805.78102 19.88 0.125 specz; rising (0.35 mag intra-night) iPTF17bal 138.036706 +06.780975 2457805.78255 19.72 0.143 specz; nuclear iPTF17bak 138.746540 +05.045414 2457805.78404 20.55 0.143 specz; nuclear (SDSS AGN); rising (0.39 mag intra-night) iPTF17bai 141.156805 +08.409091 2457805.78853 19.97 0.129 specz; nuclear? iPTF17bah 141.492784 +08.840897 2457805.78853 20.51 0.107 specz; nuclear?; rising (0.59 mag intra-night) iPTF17bag 137.893562 +06.774493 2457805.78255 20.20 0.225 photz; nuclear iPTF17bad 141.730214 +08.380390 2457805.78853 19.72 0.122 specz; nuclear? iPTF17baa 133.693265 +01.183738 2457805.78102 19.46 0.066 photz iPTF17aas 170.123758 +34.754070 2457805.89411 18.96 0.042 specz; =SN2017aas=PTSS-17dib=PS17bey, known SNIa. iPTF17mf 214.129450 +39.586295 2457805.96167 17.21 0.0257 specz; =SN2017mf, known SNIa. iPTF17jg 204.057109 +38.348005 2457805.94963 18.57 0.014 specz; =ATLAS17aic, first discovered 2017-01-09 iPTF17hy 202.138887 +39.486881 2457805.94963 20.18 0.064 specz; =Gaia17abk=PS17hc, first discovered 2017-01-12. Positions are stated in the ICRS. Times are in UTC. Magnitudes are based on image subtraction; they are in the Mould R filter and in the AB system, calibrated with respect to point sources in SDSS as described in Ofek et al. 2012. None of the above transients show prior history of detection in iPTF archival images. All of the above transients coincide with a galaxy that is visible in iPTF and/or SDSS images. Archival spectroscopic or photometric redshifts of the transients' likely host galaxies are given above. We cross-matched this list to our ongoing effort to build a more complete Census of the Local Universe (CLU; Cook et al. 2017) by identifying redshifted Halpha emitters out to 200 Mpc. The hosts of iPTF17bdq, iPTF17bdl, iPTF17bcy, iPTF17bcn, iPTF17bbe, and iPTF17bbb, are viable emission line candidates. We encourage spectroscopic classification of these candidates. In particular, we highlight iPTF17bec, iPTF17bds, iPTF17bdd, iPTF17bam, and iPTF17bah as fast-evolving by more than 0.3 mag in the same night. In addition, our local transients (d < 100 Mpc) are iPTF17jg, iPTF17bdq, iPTF17bbp, iPTF17bdl, and iPTF17bdd, and our bright transients (R < 19 mag) are iPTF17bbv, iPTF17jg, iPTF17bdd, iPTF17baz, and iPTF17beb. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20720 SUBJECT: LIGO/Virgo G274296: J-GEM optical/NIR follow-up observations DATE: 17/02/22 10:41:46 GMT FROM: Michitoshi Yoshida at J-GEM Yoshida, M. (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 G274296 (Shawhan et al. GCN20689) with the 50cm MITSuME telescopes at Akeno Observatory and Okayama Astrophysical Observatoty (OAO) and the 91cm wide field near-infrared camera (OAOWFC) in the framework of J-GEM collaboration. We obtained optical three color data, g', Rc, and Ic, simultaneously with a three color camera attached to the MITSuME telescopes. Near-infrared J-band data were obtained with OAOWFC. We listed the 5-sigma limiting AB magnitude of each observation below. No optical/infrared transit source corresponding to the GW event was found by these observations. Telescope: Akeno-MITSuME 50cm telescope ---------------------------------------------------------------------- galaxy RA DEC UT g' Rc Ic ---------------------------------------------------------------------- SDSSJ100438.01+191712.3 151.145 19.2901 2017/2/18-13:22 17.9 17.7 17.2 SDSSJ110234.52+321339.2 165.602 32.3042 2017/2/18-19:31 18.8 18.4 17.4 PGC1754917 157.824 25.9592 2017/2/18-17:58 18.9 18.4 17.5 PGC1752182 157.113 25.8593 2017/2/18-13:46 18.5 18.2 16.9 PGC031387 158.876 26.1942 2017/2/18-20:02 18.2 17.9 16.8 PGC1739538 156.843 25.4675 2017/2/18-11:20 17.9 17.2 16.5 SDSSJ103227.23+254420.0 158.106 25.8022 2017/2/18-16:58 18.8 18.3 17.4 PGC1808655 160.101 27.4668 2017/2/18-14:14 18.5 18.2 17.2 UGC06195 167.267 33.9688 2017/2/18-15:14 16.9 15.3 15.3 PGC1742220 157.981 25.6686 2017/2/18-18:29 18.9 18.4 17.6 PGC1747289 156.049 25.6424 2017/2/18-09:59 17.8 17.2 16.6 SDSSJ105042.23+315119.6 162.700 31.8200 2017/2/18-11:54 18.3 18.0 17.3 SDSSJ095947.63+193539.3 149.959 19.5236 2017/2/18-10:27 18.3 17.7 16.7 PGC029063 150.570 19.1965 2017/2/18-12:21 18.7 18.1 17.5 UGC05403 150.648 19.1695 2017/2/18-12:52 18.9 18.2 17.5 NGC3251 157.327 26.0998 2017/2/18-14:54 17.5 16.6 16.4 SDSSJ102436.95+253546.9 156.180 25.5393 2017/2/18-10:50 17.4 17.5 16.9 UGC05679 157.205 26.4013 2017/2/19-16:47 16.9 16.6 15.7 SDSSJ102858.64+251713.1 157.240 25.2823 2017/2/19-12:51 18.6 17.9 17.4 UGC05844 160.985 28.1973 2017/2/19-15:56 17.7 17.1 16.3 PGC1758620 157.748 26.0048 2017/2/19-13:23 17.1 17.0 15.8 SDSSJ101200.03+213820.3 153.035 21.5636 2017/2/19-09:50 17.9 17.0 16.4 IC2583 157.780 26.1222 2017/2/19-16:19 17.0 16.5 15.8 SDSSJ103953.27+272240.0 159.996 27.3349 2017/2/19-11:21 18.6 18.3 17.5 PGC027259 143.837 13.4901 2017/2/19-10:18 18.1 17.7 17.0 SDSSJ100552.60+202338.0 151.437 20.4614 2017/2/19-18:07 16.2 14.6 14.7 PGC028676 149.015 20.5527 2017/2/19-19:09 15.9 14.6 14.7 UGC05401 150.637 18.9816 2017/2/19-10:50 18.3 18.0 18.0 PGC1834191 161.973 28.3977 2017/2/20-14:28 19.2 18.7 17.8 SDSSJ101717.58+220939.3 154.300 22.2234 2017/2/20-16:58 19.2 18.6 17.7 PGC1815236 156.617 27.7584 2017/2/20-19:45 18.4 18.0 16.8 PGC142873 164.106 31.2584 2017/2/20-13:27 19.2 18.5 17.5 SDSSJ103934.08+270302.4 159.907 27.0091 2017/2/20-11:53 16.8 16.3 15.8 IC2590 159.049 27.0281 2017/2/20-17:30 19.0 18.3 17.5 PGC1793207 156.099 26.9558 2017/2/20-13:57 19.3 18.6 17.7 PGC1752683 157.833 25.8397 2017/2/20-12:26 16.9 16.9 16.2 SDSSJ104414.58+284206.3 161.031 28.7746 2017/2/20-18:32 18.7 18.1 17.3 PGC1662338 154.073 22.0953 2017/2/20-16:28 19.2 18.6 17.6 SDSSJ104053.41+270354.0 160.235 27.0461 2017/2/20-12:56 18.8 18.2 17.4 PGC029111 150.714 20.2397 2017/2/20-14:59 19.0 18.4 17.5 PGC1980945 166.151 32.1969 2017/2/20-19:14 18.3 17.9 16.3 PGC031406 159.008 27.0253 2017/2/20-18:00 18.8 18.3 17.3 ---------------------------------------------------------------------- Telescope: OAO-MITSuME 50cm telescope ---------------------------------------------------------------------- galaxy RA DEC UT g' Rc Ic ---------------------------------------------------------------------- UGC06384 170.492 34.9486 2017/2/18-19:03 19.4 19.5 18.9 SDSSJ094405.52+170156.0 146.023 17.0324 2017/2/18-14:09 19.4 19.3 18.7 SDSSJ093238.79+113551.7 143.162 11.5977 2017/2/18-12:50 19.2 19.1 18.6 SDSSJ092951.83+115535.7 142.466 11.9266 2017/2/18-11:32 18.3 18.5 17.9 SDSSJ092816.16+110437.4 142.067 11.0770 2017/2/18-11:13 18.2 18.4 17.9 PGC2053997 170.195 34.7511 2017/2/18-19:24 19.2 19.1 18.4 PGC1888393 162.717 30.0545 2017/2/18-20:21 18.9 18.9 18.3 PGC142873 164.084 31.2703 2017/2/18-20:02 18.6 19.2 18.5 PGC090923 143.003 12.2616 2017/2/18-11:52 19.2 18.7 18.1 PGC035503 172.781 35.5896 2017/2/18-17:05 19.4 19.3 18.7 PGC032906 164.200 31.0904 2017/2/18-19:42 19.0 19.2 18.5 PGC027259 143.841 13.5489 2017/2/18-13:10 19.4 19.4 18.3 PGC027237 143.732 11.6809 2017/2/18-13:29 19.3 19.2 18.7 PGC027113 143.216 12.2868 2017/2/18-12:31 19.1 19.1 18.6 PGC027081 143.068 12.0939 2017/2/18-12:11 18.9 19.0 18.4 NGC3694 172.226 35.4139 2017/2/18-17:45 19.4 19.4 18.8 NGC3380 162.051 28.6018 2017/2/18-20:41 18.7 18.8 18.2 NGC2954 145.100 14.9226 2017/2/18-13:50 19.3 19.3 18.7 2MASXJ11291265+3523089 172.303 35.3858 2017/2/18-17:25 19.3 19.4 18.8 ---------------------------------------------------------------------- Instrument: OAOWFC ------------------------------------------------------------- galaxy RA DEC UT J ------------------------------------------------------------- UGC05381 150.215 22.3137 2017/2/18-13:08 18.79 SDSSJ100106.15+221806.0 150.276 22.3017 2017/2/18-13:08 18.79 IC2551 152.668 24.4141 2017/2/18-13:54 18.81 PGC027113 143.216 12.2868 2017/2/18-10:39 18.26 PGC027081 143.068 12.0939 2017/2/18-10:39 18.26 UGC05420 150.995 22.2760 2017/2/18-18:44 18.51 PGC1667794 150.965 22.3239 2017/2/18-18:44 18.51 PGC1667131 150.985 22.2882 2017/2/18-18:44 18.51 PGC1666640 150.995 22.2641 2017/2/18-18:44 18.51 UGC05381 150.215 22.3137 2017/2/18-18:02 18.72 SDSSJ100106.15+221806.0 150.276 22.3017 2017/2/18-18:02 18.72 2MASXJ09532220+2026551 148.343 20.4487 2017/2/18-12:22 18.66 ------------------------------------------------------------- //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20721 SUBJECT: LIGO/Virgo G274296: PS17bek is a superluminous supernova at z=0.31 DATE: 17/02/22 12:51:03 GMT FROM: Giorgos Leloudas at Weizmann Institute of Science A. Gal-Yam, G. Leloudas, P. Vreeswijk (Weizmann), K. C. Chambers (IfA), M. E. Huber (IfA), S. J. Smartt, K. W. Smith, D. Wright, D. Young (QUB), F. Taddia, C. Barbarino, A. Nyholm, C. Fremling, J. Sollerman (OKC), M. T. Botticella (INAF-Capodimonte), M. Fraser (UCD), C. Inserra, E. Kankare, K. Maguire, M. Sullivan (Southampton), S. Valenti (UC Davis), O. Yaron, I. Manulis (Weizmann), E. Cappellaro (INAF-Padova),, M. Coughlin (Harvard), T.-W. Chen (MPE), L. Denneau, H. Flewelling, A. Heinze, T. Lowe, E. A. Magnier (IfA), A. Rest (STScI), B. Stalder, A. S. B. Schultz (IfA), C. W. Stubbs (Harvard) J. Tonry, C. Waters, R. J. Wainscoat, H. Weiland, M. Willman (IfA) report: We have reanalysed the spectrum of PS17bek obtained by PESSTO (Taddia et al. GCN 20708), an object in the sky map of G274296. The spectrum is blue but shows weak broad features and a weak emission line that was previously identified with Halpha at z=0. The object was therefore thought to be Galactic. Cross-correlating the spectrum with supernova template spectra in SNID (Blondin & Tonry, 2007), we find a good match to the spectra of super-luminous supernovae (SLSNe type I). In particular, we find a good match with the spectra of SN 2010gx at -5 days before peak if PS17bek is at a redshift of z~0.31. In this context, the weak emission line at 6559.4 is consistent with [O III] 5007 at z = 0.31, and we also detect [O III] 4959 at a consistent redshift but lower significance. The [O III] lines are typically the strongest emission lines in SLSN dwarf, starforming hosts (Leloudas et al. 2015). There is a faint, uncatalogued source in the Pan-STARRS1 3Pi r-band image which is likely the host at r~23.5 (Chambers et al. arXiv:1612.05560). We therefore classify PS17bek as a SLSN I at z = 0.31. The Pan-STARRS lightcurve is flat at i=19.8 over two days : MJD mag filter 57802.30629 19.85 i 57804.58218 19.81 i This indicates that the object is likely close to maximum light and has a rest frame absolute magnitude of M_r ~ -21.0. Although these superluminous events are relatively rare by sky density, they have rise times from explosion to peak of around 20-40 days (e.g. Nicholl et al. 2015). Therefore the explosion probably occurred at least 20 days before the GW detection of G274296 (57801.254 ; Shawhan et al. GCN20689) and is likely unrelated. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20723 SUBJECT: LIGO/Virgo G274296: PIRATE Observations DATE: 17/02/22 14:03:54 GMT FROM: Dean Roberts at PIRATE D. Roberts, M.Morrell & U. Kolb (The Open University) reporting on behalf of the PIRATE group: We observed 4 separate fields of the G274296 cWB skymap using our 0.43m robotic telescope at Teide Observatory, Tenerife, Spain. We acquired 96 images across the first night of observation, with a further 24 images taken 2 days later, all images were obtained using the R filter and 100s exposure length. Initial observations began at 2017-02-17T23:39:33, approximately 35 minutes after the initial GCN alert was received. A list of the 4 fields observed is given below, each with FoV of 0.7x0.7 degrees centred around the given coordinates. Analysis is ongoing. Field RA Dec #1: 150.0 20.0 #2: 157.5 25.0 #3: 153.75 22.0 #4: 142.5 15.0 -- 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: 20724 SUBJECT: LIGO/Virgo G274296: No change to estimate of LIGO false alarm probability DATE: 17/02/22 14:19:02 GMT FROM: Karelle Siellez at Georgia Inst of Tech The LIGO Scientific Collaboration and Virgo report: The Coherent WaveBurst event candidate of 2017-02-17, with GraceDB ID G274296, was initially reported (LSC and Virgo, GCN 20689) with an estimated false alarm rate (FAR) of 1.7e-7 Hz, or about 5.4 per year. Offline re-analysis has not changed this estimate. At this time, we do not have any evidence suggesting that the significance of this event will increase on further study. Also, the (potential) signal in the data is inconsistent with a compact binary coalescence waveform. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20727 SUBJECT: LIGO/Virgo G274296: HAWC follow-up DATE: 17/02/22 20:40:53 GMT FROM: Andrew Smith at U Maryland A. Smith (UMD) and I. Martinez (UMD) report on behalf of the HAWC Collaboration HAWC was operating and our real-time all-sky GRB monitoring analysis was running at the time of the G274296 event. At the time of the event, the HAWC detector was oriented at (α, δ) = (141.4°, 19.0°), local zenith. 62% of the LIGO/Virgo CWB probability contour fall within our observable field (0-45 deg zenith angle). We 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 on 4 timescales (0.1,1, 10, 100 sec) with a reduced threshold to account for the reduced number of trials. No candidates were identified. Additionally, we searched for longer duration emission by observing the candidate locations beginning from the time of the trigger as they transited the FOV, roughly 3 hrs or half of a full transit for most of the observable contour. This analysis is optimized for ~0.5-100TeV. We found no evidence of emission. The 5-sigma detection sensitivity of this search varies from roughly 1.4-3 x the flux of the Crab. 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. (learn more http://hawc-observatory.org) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20730 SUBJECT: LIGO/Virgo G274296: CALET Observations DATE: 17/02/24 00:36:19 GMT FROM: Takanori Sakamoto at Aoyama Gakuin U M. Moriyama, A. Yoshida, T. Sakamoto, Y. Kawakubo, Y. Yamada (AGU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA), I. Takahashi (IPMU), Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), W. Ishizaki (ICRR), M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena) and the CALET collaboration: The CALET Gamma-ray Burst Monitor (CGBM) was operating at the trigger time of G274296 (GCN Circ. 20689). No CGBM on-board trigger occurred at the time of the event. Based on the LIGO localization sky map (skyprobcc_cWB.fits), the part of the northern arc of the high probability area was in the field-of-view of CGBM. The summed LIGO probabilities inside the HXM and the SGM field of view are 1% and 20%. Based on the analysis of the light curve data with 0.125 sec time resolution from -60 sec to 60 sec from the trigger time, we found no significant excess around the trigger time in either the HXM (7-1000 keV) or the SGM (0.1-20 MeV) data. The CALET Calorimeter (CAL) was operating in high energy trigger mode at the trigger time of G274296. However, no LIGO error region was included in the CAL's field of view at the time of the trigger. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20732 SUBJECT: LIGO/Virgo G274296: MASTER new OT DATE: 17/02/24 13:21:31 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.M. Lipunov, V.Shumkov, E. Gorbovskoy, N.Tyurina, 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 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 V.Yurkov, Yu.Sergienko, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk MASTER continues inspection of LIGO event G274296 (Shawhan et al. GCN 20689, Lipunov et al. GCN 20696, GCN 20715; 20712; ). The cover map of MASTER inspection survey, the position of MASTER OTs inside LIGO error-box is presented at http://master.sai.msu.ru/static/MASTERGW170217full.jpg MASTER OT J184722.28-834543.4 discovery - new optical transients, no known sources in VIZIER database. MASTER-OAFA auto-detection system discovered OT source at (RA, Dec) = 18h 47m 22.28s -83d 45m 43.4s on 2017-02-24.13990 UT with unfiltered m_OT=17.6m (mlimit=19.4m). The OT is seen in 2 images. There is no minor planet at this place. We have reference images without OT on 2017-01-26.20851 UT with 19.7m unfiltered magnitude limit in MASTER-OAFA, on 2016-08-05 18:16:52UT with mlim=19.5, on 2016-03-02 23:53:05 with mlim=20.0, 2015-04-26 23:34:52 with mlim=20.0, on2015-01-12 01:41:57UT with mlim=19.6 in MASTER-SAAO database. There is no any known sources inside 8" in VIZIER database, it means 22mag of POSS historical limits and more then 4.4magnitude of current outburst amplitude. Spectral observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/184722.28-834543.4.png //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20734 SUBJECT: LIGO/Virgo G274296: Liverpool Telescope classification of EM candidates DATE: 17/02/24 22:14:36 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 report the following Liverpool Telescope follow-up observations of EM candidates. Observations were made with the SPRAT spectrograph, and supernova classifications were obtained using SNID (Blondin & Tonry, 2007, ApJ, 666, 1024). iPTF17bam was observed on 2017-02-22 at 23:04UT. The transient is centrally located within its host galaxy and the spectrum is indicative of an AGN. iPTF17bds was observed on 2017-02-24 at 04:36UT. We classify this transient as a type Ia SN at +8 days with z=0.203. PS17bfg was observed on 2017-02-24 at 03:46UT. We classify this transient as a type Ia SN at +15 days with z=0.140. The galaxy 2MASX J11453974+3323354 at a separation of 0.064 arcmin has catalogue z=0.141258. PTSS17gpm was observed on 2017-02-24 at 05:02UT. We classify this transient as a type Ia SN at +1 days with z=0.080. iPTF17beb was observed on 2017-02-24 at 05:53UT. We classify this transient as a type II SN at +17 days with z=0.056. We also observed the following targets. In these targets the spectrum seems to be dominated by the host galaxy and we see no evidence of a transient above the host galaxy emission in the acquisition images. In the majority of cases the transient coordinates are very close to the centre of the host galaxy. iPTF17bah was observed on 2017-02-23 at 00:33UT. iPTF17baz was observed on 2017-02-24 at 01:07UT. PS17bfc was observed on 2017-02-24 at 02:04UT. iPTF17bdl was observed on 2017-02-24 at 02:44UT. iPTF17bdd was observed on 2017-02-24 at 03:41UT. iPTF17bec was observed on 2017-02-24 at 05:33UT. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20736 SUBJECT: LIGO/Virgo G274296: GRAWITA-Campo Imperatore observation DATE: 17/02/25 17:06:09 GMT FROM: Enzo Brocato at INAF-OA Roma A. Giunta, A. Di Paola, M. Centrone, N. Napoleone, P. Tedesco (INAF-OAR), G. Greco, M. Branchesi (Urbino University/INFN Firenze), S. Covino (INAF-OAB), L. Amati (INAF-IASF Bo), L. A. Antonelli, S. Ascenzi (INAF-OAR), M.T. Botticella (INAF-OAC), S. Campana (INAF-OAB), E. Cappellaro (INAF OAPd), P. D'Avanzo (INAF-OAB), V. D'Elia (INAF-ASDC), F. Getman, A. Grado, L. Limatola (INAF-OAC), M. Lisi (INAF-OAR), A. Melandri (INAF-OAB), L. Nicastro, E. Palazzi (INAF-IASF Bo), E. Pian (SNS-Pisa), S. Piranomonte, 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, S. Yang (INAF-OAPD), E. Brocato (INAF-OAR) on behalf of GRavitational Wave Inaf TeAm (GRAWITA) report: We carried out observations of LIGO/Virgo G274296 (LVC, GCN 20689) with the 0.9m Schmidt Telesope located at the Campo Imperatore Observatory (Italy). The observations were taken in the r-sloan band on 2017-02-19 starting at 01:21:55 UT relatively good sky conditions. The covered area captured a containment probability of ~5% and was chosen to maximize the number of local (< 30 Mpc) galaxies to be observed. The area is divided in 4 blocks of 3x3 pointing each of them of covering 1.15x1.15 square degrees of the sky and 5x90 sec exptime each. The pointing sequence was generated using the GWsky script (https://github.com/ggreco77/GWsky) starting from the high probability region of the bayestar skymap and taking into account the airmass and relative density of nearby galaxies. The pointings are centered on the following UT times, coordinates RA, Dec (J2000) and observed area: 2017-02-19T21:22:04 137.106 5.926 1.15x1.15 square degrees 2017-02-19T04:16:28 166.43 28.33 1.15x1.15 square degrees 2017-02-19T04:10:14 162.47 28.01 1.15x1.15 square degrees 3x3 pointing blocks 2017-02-19T02:54:33 157.481 28.318 ~3x~3 square degrees 2017-02-19T01:21:55 157.34 23.988 ~3x~3 square degrees 2017-02-19T23:35:11 157.22 20.9 ~3x~3 square degrees 2017-02-19T21:33:26 153.709 21.68 ~3x~3 square degrees The limiting magnitude is r ~ 20.5. Analysis of images is ongoing. -- Enzo Brocato INAF - Osservatorio Astronomico di Roma Via di Frascati 33, I-00040 Monteporzio Catone, Italy Phone: +39 0694286438 Fax: +39 06 9447243 skype: enzo.brocato URL: SpoT Group Homepage: www.oa-teramo.inaf.it/SPoT //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20744 SUBJECT: LIGO/Virgo G274296: Swift/BAT data search DATE: 17/02/26 01:48:50 GMT FROM: Takanori Sakamoto at Aoyama Gakuin U D.M. Palmer (LANL), S.D. Barthelmy (NASA/GSFC), A. Y. Lien (GSFC/UMBC), T. Sakamoto (AGU), A. A. Breeveld (MSSL-UCL), A.P. Beardmore (U. Leicester), D.N. Burrows (PSU), S. Campana (INAF-OAB), S.B. Cenko (NASA/GSFC), G. Cusumano (INAF-IASF PA), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB), V.D'Elia(ASDC), P.A. Evans (U. Leicester), N. Gehrels (NASA/GSFC), P. Giommi (ASI), C. Gronwall (PSU), J. A. Kennea (PSU), H.A. Krimm (CRESST/GSFC/USRA), N.P.M. Kuin (UCL-MSSL), D. Malesani (DARK/NBI), F.E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), B. Mingo (U. Leicester), J.A. Nousek (PSU), S.R. Oates (Uni. of Warwick), P.T. O'Brien (U. Leicester), J.P. Osborne (U. Leicester), C. Pagani (U. Leicester), K.L. Page (U.Leicester), M. Perri (ASDC), J.L. Racusin (NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU), M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB), E. Troja (NASA/GSFC/UMCP) report on behalf of the Swift team: We report the search results in the BAT data within T0 $B!^(B 100 s of the LIGO event G274296 (LIGO/VIRGO Collaboration GCN Circ. 20689), where T0 is the LIGO trigger time (2017-02-17T06:05:55.050 UTC). The BAT pointing position at T0 is RA = 133.700 deg, DEC = 20.061 deg, ROLL = 319.960 deg. The BAT Field of View (>0.1 partial coding) covers 65.49% of the integrated LIGO localization probability. The closest event data covers the time range from T0-26.67 to T0-23.61, and from T0+48.33 to T0+134.46. No sources with signal-to-noise ratio > 6 sigma are found in these event data. Also, no significant detections (signal-to-noise ratio > 4 sigma) are found in the BAT raw light curves with time bins of 64 ms, 1 s, and 1.6 s, respectively. Assuming an on-axis (100% coded) short GRB with a typical spectrum in the BAT energy range (i.e., a simple power-law model with a power-law index of -1.32; Lien & Sakamoto et al. 2016), the 4-sigma upper limit in the 1-s binned light curve corresponds to a flux upper limit (15-350 keV) of ~ 6.9 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 17.86% 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: 20747 SUBJECT: LIGO/Virgo G274296: P200 classification of EM candidates DATE: 17/02/26 07:31:27 GMT FROM: Mansi M. Kasliwal at Caltech R. Lunnan (Caltech), D. Cook (Caltech), K. De (Caltech) and M. M. Kasliwal (Caltech) report on behalf of the iPTF and GROWTH collaborations Under cloudy and windy weather conditions, the following classification spectra were obtained with the Palomar 200-in telescope using the DBSP spectrograph (Oke & Gunn, 1982, PASP, 94, 586). ATLAS17aic (=iPTF17jg) was observed on 2017-02-23 13:03 UT. The spectrum shows strong galaxy emission lines at z=0.013 and a broad P-cygni Halpha profile, consistent with a Type II SN a few weeks after maximum light. PS17bew (=iPTF17bbq) was observed on 2017-02-23 10:33 UT . The spectrum shows broad Halpha emission, consistent with a Type II SN, confirming the classification reported by PESSTO (ATel #10127). iPTF17bdd was observed on 2017-02-23 11:48 UT. The spectrum is dominated by galaxy light, as was also the case in the spectrum reported from Liverpool Telescope (LVC GCN #20734). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20761 SUBJECT: LIGO/Virgo G274296: MASTER new PSN detected on 22 feb DATE: 17/02/27 11:40:34 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.M. Lipunov, T.Pogrosheva, S.Kobelev, V.Shumkov, E. Gorbovskoy, N.Tyurina, P.Balanutsa, O.Gress, V.Kornilov, A.Kuznetsov, M.I.Panchenko, A.V.Krylov, I.Gorbunov Lomonosov Moscow State University, Sternberg Astronomical Institute 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 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 V.Yurkov, Yu.Sergienko, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk MASTER OT J072511.84-881702.0 discovery - PSN in cluster's galaxy MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 07h 25m 11.84s -88d 17m 02.0s on 2017-02-22.81740 UT. The OT unfiltered magnitude is ~19.0m (mlim=20.2). The OT is seen in 4 image. There is no minor planet at this place. This PSN is in 12" from bright galaxy (USNO B1 0017-0004125, B2=15.9,R2=15.3). There is a cluster of galaxies in this area. We have reference image on 2015-04-15.98271 UT with unfiltered m_lim= 20.6m. Spectral observations are required. http://master.sai.msu.ru/static/OT/MASTEROTJ072511.84-881702.0.jpg //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20780 SUBJECT: LIGO/Virgo G274296 and G275404 : MAXI/GSC observations DATE: 17/03/01 06:37:30 GMT FROM: Satoshi Sugita at Tokyo Inst. of Tech. S. Sugita, N. Kawai (Tokyo Tech), M. Serino (RIKEN), H. Negoro (Nihon U.), S. Ueno, H. Tomida, S. Nakahira, M. Ishikawa, Y. Sugawara (JAXA), Y. E. Nakagawa (JAMSTEC), T. Mihara, M. Sugizaki, W. Iwakiri, M. Shidatsu, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN), N.Isobe, T. Yoshii, Y. Tachibana, Y. Ono, T. Fujiwara, S. Harita, Y. Muraki (Tokyo Tech), A. Yoshida, T. Sakamoto, Y. Kawakubo, Y. Kitaoka (AGU), H. Tsunemi, R. Shomura (Osaka U.), M. Nakajima, K. Tanaka, T. Masumitsu, T. Kawase (Nihon U.), Y. Ueda, T. Kawamuro, T. Hori, A. Tanimoto, S. Oda (Kyoto U.), Y. Tsuboi, Y. Nakamura, R. Sasaki (Chuo U.), M. Yamauchi, K. Furuya (Miyazaki U.), K. Yamaoka (Nagoya U.) report on behalf of the MAXI team: We examined the MAXI/GSC all-sky X-ray images (2-20 keV) obtained in the orbit and the day after the LVC trigger G274296 at 2017-02-17 06:05:55.050 UTC (GCN 20689) and G275404 at 2017-02-25 18:30:21.374 UTC (GCN 20738). MAXI/GSC did not observe (HV off) at the trigger time of G274296, and observed from T0+843 sec. MAXI/GSC scanned more than 87% of the whole sky in the 92-min orbit, which includes 77.4% of the 90% regions in the skyprobcc_cWB skymap. One day image covers 89.7% of the 90% regions in the skyprobcc_cWB skymap. No significant new source was found in these images. The upper limits for the X-ray flux are different depending on the part of the sky. For instance, typical 2-20 keV 1-sigma (3-sigma) upper limits obtained from the one-orbit and one-day images are 40 (120) mCrab and 15 (35) mCrab, respectively, which was larger than the typical upper limits of GSC because anti-coincidence function of one of the GSC cameras was disabled. In G275404 observation, MAXI/GSC did not observe at the trigger time and observed from T0+1246 sec. MAXI/GSC scanned more than 62% of the whole sky in the one orbit, which includes 55.0% of the 90% regions in the bayestar skymap. One day image covers 96.3% of the 90% regions in the bayestar skymap. No significant new source was found in these images. For instance, typical 2-20 keV 1-sigma (3-sigma) upper limits obtained from the one-orbit and one-day images are 12 (36) mCrab and 3 (9) mCrab, respectively. MAXI/GSC also observed the position of the possible gamma-ray transient (GCN 20754), but it was difficult to estimate upper limits because the effect of stray photon from bright GRS 1915+105 near by the localized position of the transient was large. //////////////////////////////////////////////////////////////////////// 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: 20849 SUBJECT: SN MASTER OT J042250.16-820415.4 is the possible optical counterpart of the gravitational waves event LIGO/Virgo G274296 DATE: 17/03/11 17:23:15 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.M. Lipunov, E. Gorbovskoy, N.Tyurina, V.G. Kornilov, P.Balanutsa, A.Kuznetsov, V.Shumkov, O.Gress, M.I.Panchenko, A.V.Krylov, I.Gorbunov Lomonosov Moscow State University, Sternberg Astronomical Institute 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 N.M. Budnev, O. Gress, K. Ivanov Irkutsk State University 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, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory V.Yurkov, Yu.Sergienko, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk MASTER-OAFA (Argentina) auto-detection system discovered MASTER OT J042250.16-820415.4 as bright OT at (RA, Dec) = 04 22 49.70 -82 04 10.0 on 2017-02-19.12023UT during inspection (Lipunov et al. GCN 20696, GCN 20711) of LIGO/VIRGO G274296 event (Peter Shawhan, GCN 20689) http://master.sai.msu.ru/static/OT/MASTEROTJ042250.16-820415.4.jpg . This SN is located near the maximal probability area of southern part of this GW event error-box. MASTER-SAAO started inspection of this SN every night with W,B,I,R and V filters (21 nights at this moment). We have good accuracy of its photometry, i.e. the detailed registered WBIRV light curve before and during its maximum. "W" - is the unfiltered. This SN is in 2.6E,11.9N offset from the center of galaxy with low surface brightness ESO015-010 (PGC014998) with Btc =16.54m and Bri25=24.63m (mean surface brightness within 25th-mag isophote). On the 25th of Feb 2017 PESSTO detected its type (Ia) and z=0.02 (Nyholm et al. ATel #10131) We carried out a preliminary joint analysis of the light curves of MASTER OT J042250.16-820415.4 with respect to supernovae of the similar brightness in order to determine the time of explosion of this supernova. Figure http://master.sai.msu.ru/static/MASTEROTJ042250.16-820415.4.png shows that MASTEROTJ042250.16-820415.4 supernova reach maximum brightneses ~ 15 days after LIGO G274296 trigger. This fact shows that the SN explosion time is very close to the LIGO G274296 trigger and this SN could be the progenitor of this event. The ESO 15-10 galaxy photometrical distance is about 84.6 Mpc for Omega_Lambla=0.7+-0.1, Omega_tot=1 an H=72+/-2 km/s/Mpc. The maximal magnitute in B filter is about M(B) = -19.5+/-0.1 The error include the uncertainty of the cosmological parameters. This is preliminary analysis of the observations. Recently one of us noted that double O-Ne-Mg white dwafs merging can be produce powerfull non spiralling waveform gravitational waves for LIGO/VIRGO type interferometers (Lipunov V.M., arXiv: AstroPh, submission number 1830243; will be appear 13.03.2017; submitted to New Astronomy). So we conclude that SNIa MASTER OT J042250.16-820415.4 in ESO 15-10 galaxy is the real optical counterpart of the gravitational waves event LIGO/Virgo G274296 . All observations are required. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20875 SUBJECT: LIGO/Virgo G274296: DLT40 follow-up observation DATE: 17/03/15 21:29:54 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) report on behalf of the Gravitational Wave Follow-Up by DLT40. We report the observation of 25 galaxies within the LVC error region for the GW trigger G274296 using the cWB localization map.We selected 46 galaxies from the GWGC catalogue within 80.0% of the trigger error region, within a distance of 40.0 Mpc, brighter that -17.5 mag and at a Declination < 20 degree. 25 of those galaxies have been observed using the Prompt 5 telescope and are part of the ongoing DLT40 search. They represent the 1.3% of all galaxies within 40.0 Mpc in the Glade catalogue within the LVC error region for the GW trigger and contains 6.1% of all B band luminosity of those galaxies. We started to observe these sample of galaxies on 2017-2-17 and monitored them for 3 weeks after the GW trigger. No interesting transients have been identified down to a limit magnitude of 18.5. Below follow the list of galaxies observed: Name RA(J2000) DEC(J2000) Dist(Mpc) BMAG KMAG IC2367 126.042 -18.7755 29.18 -20.71 -23.8874 NGC2775 137.5837 7.0379 17.3 -20.17 -24.1532 NGC3041 148.2798 16.6777 23.77 -19.86 -23.1421 PGC023658 126.4918 -11.7792 38.93 -19.84 -21.7084 NGC2695 133.6128 -3.067 32.36 -19.76 -23.695 PGC024778 132.2517 -7.8298 38.02 -19.75 -22.3331 NGC2894 142.3758 7.7179 30.49 -19.75 -23.3068 NGC2722 134.6925 -3.71 38.02 -19.68 -22.4881 NGC3226 155.8624 19.8984 23.55 -19.59 -23.29 NGC2919 143.6982 10.2837 34.67 -19.54 -22.6498 NGC2906 143.026 8.4419 29.92 -19.28 -23.2668 NGC3020 147.5274 12.8136 21.88 -19.2 -21.0172 NGC2708 134.0337 -3.36 26.55 -19.15 -23.2403 PGC023723 126.892 -12.7566 34.61 -19.08 -21.689 UGC05467 152.0539 18.7071 39.71 -18.96 -22.1495 NGC3024 147.6141 12.7655 25.35 -18.92 -20.8419 NGC2698 133.9023 -3.1838 24.94 -18.89 -23.1405 IC0540 142.5429 7.9027 28.64 -18.75 -21.7699 NGC2690 133.1584 -2.6032 21.04 -18.61 -21.9722 NGC2697 133.7475 -2.9876 24.17 -18.59 -22.0234 NGC2612 128.4585 -13.1747 21.67 -18.59 -22.9033 UGC04684 134.1696 0.375 35.67 -18.54 -20.5195 NGC2706 134.0512 -2.5634 21.88 -18.48 -22.1752 UGC05403 150.6481 19.1769 33.42 -18.48 -22.284 UGC04845 138.1077 9.9555 30.18 -18.33 -20.6846 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21284 SUBJECT: LIGO/Virgo G274296: Updated localization from LIGO data DATE: 17/06/29 20:29:07 GMT FROM: Marco Drago at Albert Einsein Inst/Hanover The LIGO Scientific Collaboration and Virgo report: We have performed the off-line analysis of the LIGO data around the time of the burst event G274296 using the Coherent WaveBurst (Klimenko et al., PRD 93, 042004 (2016)) with a better estimation of the background. The new estimated FAR is one event in 6 months. The low significance of this candidate is not expected to improve with further analysis. An updated localization, skyprobcc_cWB_170629.fits, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/events/G274296 This is the preferred sky map at this time. The localization is consistent with the previous sky map, however, its error region is smaller due to improved calculation of the coherent Waveburst skymaps for the low SNR events. The 50% credible region spans 245 deg2 and the 90% credible region spans 1153 deg2. Further updates on our analysis of this event will be sent as they become available. [GCN OPS NOTE(29jun17): Per adminstrator's request, the author-generated 5-line title block was removed, leaving only the GCN-generated 5-line title block.]