//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25112 SUBJECT: LIGO/Virgo S190720a: Upper limits from IceCube neutrino searches DATE: 19/07/20 01:58:20 GMT FROM: Stefan Countryman at ICECUBE/Columbia U IceCube Collaboration (http://icecube.wisc.edu/) reports: Searches [1,2] for track-like muon neutrino events detected by IceCube consistent with the sky localization of gravitational-wave candidate S190720a in a time range of 1000 seconds [3] centered on the alert event time (2019-07-20 00:00:16.747 UTC to 2019-07-20 00:16:56.747 UTC) have been performed. During this time period IceCube was collecting good quality data. No significant track-like events are found in spatial coincidence of S190720a calculated from the map circulated in the 1-Preliminary notice. IceCube's sensitivity assuming an E^-2 spectrum (E^2 dN/dE) to neutrino point sources within the locations spanned by the 90% spatial containment of S190720a ranges from 0.029 to 1.080 GeV cm^-2 in a 1000 second time window. The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc@icecube.wisc.edu [1] Bartos et al. arXiv:1810.11467 (2018) and Countryman et al.arXiv:1901.05486 (2019) [2] Braun et al., Astroparticle Physics 29, 299 (2008) [3] Baret et al., Astroparticle Physics 35, 1 (2011) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25113 SUBJECT: LIGO/Virgo S190720a: No counterpart candidates in HAWC observations DATE: 19/07/20 02:32:09 GMT FROM: Antonio Galvan at Inst.de Astronomia,UNAM The HAWC Collaboration (https://www.hawc-observatory.org) reports: The HAWC Collaboration performed a follow-up of the gravitational wave trigger S190720a. At the time of the trigger the HAWC local zenith was oriented towards (RA, Dec) = (202.1deg, 19.1deg). 35% of the GW candidate sky location probability fell within our observable field of view (0-45 deg zenith angle). We performed a search for a short timescale emission using 6 sliding time windows (dt = 0.3s, 1s, 3s, 10s, 30s and 100s), shifted forward in time by 20% of their width. We searched the 95% probability containment area in a timescale-dependent time period, from t0-5dt to t0+10dt, where t0 is the time of the GW trigger. No significant gamma-ray detection above the background was observed. The sensitivity of this analysis is greatly dependent on zenith angle, ranging from 0deg to 45deg for the area searched in this analysis. The 5sigma detection sensitivity to a 1s (100s) burst in the 80-800GeV energy range goes from 1.2e-06 erg/cm^2 to 1.1e-04 erg/cm^2 (6.4e-06 erg/cm^2 to 5.0e-04 erg/cm^2), depending on the zenith angle. HAWC is a TeV gamma ray water Cherenkov array located in the state of Puebla, Mexico. It is sensitive to the energy range ~0.1-100TeV, and monitors 2/3 of the sky every day with an instantaneous field-of-view of ~2 sr. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25114 SUBJECT: LIGO/Virgo S190720a Global MASTER-Net observations report DATE: 19/07/20 02:45:17 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov (Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA), H.Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE), R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias) D. Buckley (South African Astronomical Observatory), O.A. Gres, N.M. Budnev, O.Ershova (Irkutsk State University, API), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University) MASTER-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) started inspect of the LIGO/Virgo S190720a errorbox 1846 sec after notice time and 2062 sec after trigger time at 2019-07-20 00:42:58 UT, with upper limit up to 16.4 mag. The observations began at zenit distance = 78 deg. The sun altitude is -36.1 deg. The galactic latitude b = -60 deg., longitude l = 98 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/ligo_1.php?id=10525 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 2152 | 2019-07-20 00:42:58 | MASTER-OAFA | ( 1h 8m 45.30s , -66d 6m 16.82s) | C | 180 | 16.4 | 2682 | 2019-07-20 00:51:47 | MASTER-OAFA | ( 1h 3m 44.19s , -64d 6m 37.00s) | C | 180 | 16.0 | 3167 | 2019-07-20 00:59:52 | MASTER-OAFA | ( 1h 22m 04.77s , -64d 6m 07.17s) | C | 180 | 15.9 | 3653 | 2019-07-20 01:07:58 | MASTER-OAFA | ( 0h 55m 50.61s , -60d 6m 41.48s) | C | 180 | 15.1 | 4137 | 2019-07-20 01:16:02 | MASTER-OAFA | ( 1h 22m 03.76s , -64d 6m 04.84s) | C | 180 | 15.8 | 4675 | 2019-07-20 01:25:01 | MASTER-OAFA | ( 1h 11m 53.80s , -60d 6m 31.76s) | C | 180 | 15.0 | 5160 | 2019-07-20 01:33:05 | MASTER-OAFA | ( 0h 21m 11.67s , -56d 7m 01.30s) | C | 180 | 15.2 | 5657 | 2019-07-20 01:41:22 | MASTER-OAFA | ( 0h 20m 09.20s , -54d 6m 41.58s) | C | 180 | 15.0 | 8034 | 2019-07-20 02:20:59 | MASTER-OAFA | ( 0h 33m 48.98s , -54d 6m 47.83s) | C | 180 | 14.8 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25115 SUBJECT: LIGO/Virgo S190720a: Identification of a GW compact binary merger candidate DATE: 19/07/20 02:49:14 GMT FROM: Shaon Ghosh at UWM The LIGO Scientific Collaboration and the Virgo Collaboration report: We identified the compact binary merger candidate S190720a during real-time processing of data from LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at 2019-07-20 00:08:36.704 UTC (GPS time: 1247616534.704). The candidate was found by the PyCBC Live [1], SPIIR [2], MBTAOnline [3], and GstLAL [4] analysis pipelines. S190720a is an event of interest because its false alarm rate, as estimated by the online analysis, is 3.8e-09 Hz, or about one in 8 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S190720a Since the time of issuing the Preliminary GCN Notice at Sat 20 Jul 19 00:11:25 UTC, several other candidate events were discovered by search pipelines. As a result, the preferred (event) data products had to be manually selected. This caused such preferred data products (skymap, p_astro, em_bright), as they appear in GraceDB, to change until about the time of issuing the Initial GCN Notice at Sat 20 Jul 19 02:01:07 UTC. At the time of issuing the Initial GCN Notice and this GCN Circular, all data products have been finalized. The classification of the GW signal, in order of descending probability, is BBH (99%), Terrestrial (1%), BNS (<1%), NSBH (<1%), or MassGap (<1%). Assuming the candidate is astrophysical in origin, there is strong evidence against the lighter compact object having a mass < 3 solar masses (HasNS: <1%). Using the masses and spins inferred from the signal, there is strong evidence against matter outside the final compact object (HasRemnant: <1%). One sky map is available at this time and can be retrieved from the GraceDB event page: * bayestar.fits.gz, an updated localization generated by BAYESTAR [5], distributed via GCN notice about 2 hours after the candidate. This replaces the sky map that was sent with the Preliminary GCN Notice about 2 minutes after the candidate. For the bayestar.fits.gz sky map, the 90% credible region is 1461 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1071 +/- 323 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo Public Alerts User Guide . [1] Nitz et al. PRD 98, 024050 (2018) [2] Qi Chu, PhD Thesis, The University of Western Australia (2017) [3] Adams et al. CQG 33, 175012 (2016) [4] Messick et al. PRD 95, 042001 (2017) [5] Singer & Price PRD 93, 024013 (2016) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25116 SUBJECT: LIGO/Virgo S190720a: AGILE-MCAL observations DATE: 19/07/20 05:02:11 GMT FROM: Claudio Casentini at INAF-IAPS C.Casentini (INAF/IAPS), F.Lucarelli (SSDC, and INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), M.Cardillo, G.Piano, A.Ursi (INAF/IAPS), F.Verrecchia, C. Pittori (SSDC, and INAF/OAR), A. Bulgarelli, V. Fioretti, N. Parmiggiani (INAF/OAS-Bologna), M. Pilia (INAF/OA-Cagliari), F. Longo (Univ. Trieste, and INFN Trieste) report on behalf of the AGILE Team: In response to the LIGO/Virgo GW event S190720a at T0 = 2019-07-20 00:08:36.747 (UT), a preliminary analysis of the AGILE Minicalorimeter (MCAL) triggered data found no event candidate at T0. Three-sigma upper limits (ULs) are obtained for a 1 sec integration time at T0 for different celestial positions within the accessible 90% c.l. localization region (LR) of S190720a (almost 65% of the LR), from a minimum of 1.39E-06 erg cm^-2 to a maximum of 5.02E-06 erg cm^-2 (assuming as spectral model a single power law with photon index 1.5). We notice an MCAL trigger event 2.53 sec after T0 in the 32 msec lightcurve with a S/N of 5.1. We are assessing the statistical significance of this feature. The AGILE-MCAL detector is a CsI detector with a 4 pi FoV, sensitive in the energy range 0.4-100 MeV. Additional analysis of AGILE data is in progress. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25118 SUBJECT: LIGO/Virgo S190720a: Coverage and upper limits from MAXI/GSC observations DATE: 19/07/20 05:17:16 GMT FROM: Motoko Serino at RIKEN/MAXI N. Kawai, M. Sugizaki (Tokyo Tech), H. Negoro (Nihon U.), S. Sugita, M. Serino (AGU), M. Nakajima, W. Maruyama, M. Aoki, K. Kobayashi (Nihon U.), S. Nakahira, T. Mihara, T. Tamagawa, M. Matsuoka (RIKEN), T. Sakamoto, H. Nishida, A. Yoshida (AGU), Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai, T. Sato (Chuo U.), M. Shidatsu (Ehime U.), M. Oeda, K. Shiraishi (Tokyo Tech), S. Ueno, H. Tomida, M. Ishikawa, Y. Sugawara, N. Isobe, R. Shimomukai, M. Tominaga (JAXA), Y. Ueda, A. Tanimoto, S. Yamada, S. Ogawa, K. Setoguchi, T. Yoshitake (Kyoto U.), H. Tsunemi, T. Yoneyama, K. Asakura, S. Ide (Osaka U.), M. Yamauchi, S. Iwahori, Y. Kurihara, K. Kurogi, K. Miike (Miyazaki U.), T. Kawamuro (NAOJ), K. Yamaoka (Nagoya U.), Y. Kawakubo (LSU) report on behalf of the MAXI team: We examined MAXI/GSC all-sky X-ray images (2-20 keV) after the LVC trigger S190720a at 2019-07-20 00:08:36.747 UTC (GCN 25115). At the trigger time of S190720a, the high-voltage of MAXI/GSC was off, and it was turned on at T0+1076 sec (+17.9 min). The first one-orbit (92 min) scan observation with GSC after the event covered 90% of the 90% credible region of the bayestar skymap from 00:26:32 to 01:35:16 UTC (T0+1076 to T0+5200 sec). No significant new source was found in the region in the one-orbit scan observation. A typical 1-sigma averaged upper limit obtained in one scan observation is 20 mCrab at 2-20 keV. If you require information about X-ray flux by MAXI/GSC at specific coordinates, please contact the submitter of this circular by email. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25119 SUBJECT: LIGO/Virgo S190720a: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation DATE: 19/07/20 07:42:37 GMT FROM: Maeve Doyle at U College Dublin, Ireland Maeve Doyle (UCD, Ireland), Alexander Lutovinov (IKI, Russia), V. Savchenko, C. Ferrigno (ISDC/UniGE, Switzerland), J. Rodi (IAPS-Roma, Italy), A. Coleiro (APC, France), S. Mereghetti (INAF IASF-Milano, Italy) on behalf of the INTEGRAL multi-messenger collaboration: https://www.astro.unige.ch/cdci/integral-multimessenger-collaboration Using combination of INTEGRAL all-sky detectors (following [1]): SPI/ACS, IBIS/Veto, and IBIS we have performed a search for a prompt gamma-ray counterpart of S190720a (GCN 25115). At the time of the event (2019-07-20 00:08:36 UTC, hereafter T0), INTEGRAL was operating in nominal mode. The peak of the event localization probability was at an angle of 112 deg with respect to the spacecraft pointing axis. This orientation implies strongly suppressed (7% of optimal) response of ISGRI, strongly suppressed (31% of optimal) response of IBIS/Veto, and near-optimal (70% of optimal) response of SPI-ACS. The background within +/-300 seconds around the event was rather stable (excess variance 1.2). We have performed a search for any impulsive events in INTEGRAL SPI- ACS (as described in [2]), IBIS, and IBIS/Veto data. We do not detect any significant counterparts and estimate a 3-sigma upper limit on the 75-2000 keV fluence of 1.8e-07 erg/cm^2 (within the 50% probability containment region of the source localization) for a burst lasting less than 1 s with a characteristic short GRB spectrum (an exponentially cut off power law with alpha=3D-0.5 and Ep=3D600 keV) occurring at any time in the interval within 300 s around T0. For a typical long GRB spectrum (Band function with alpha=3D-1, beta=3D-2.5, and Ep=3D300 keV), the derived peak flux upper limit is ~1.5e-07 (5.6e-08) erg/cm^2/s at 1 s (8 s) time scale in 75-2000 keV energy range. For the mean reported distance 1071.0 Mpc this corresponds to the limit on the total isotropic equivalent energy in 1 s of 2.5e+49 erg for the short GRB spectrum and for a long GRB spectrum isotropic equivalent luminosity in 1 s (8 s) of 2.1e+49 erg/s (7.7e+48 erg/s) All results quoted are preliminary. This circular is an official product of the INTEGRAL Multi-Messenger team. [1] Savchenko et al. 2017, A&A 603, A46 [2] Savchenko et al. 2012, A&A 541A, 122S [GCN OPS NOTE(20jul19): There was a format error caused by a copy-paste error in the original submission. Per author's request, it has been manually reconstructed in plain text here.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25120 SUBJECT: LIGO/Virgo S190720a : no neutrino counterpart candidate in ANTARES search DATE: 19/07/20 10:12:24 GMT FROM: Antoine Kouchner at ANTARES Collaboration M. Ageron (CPPM/CNRS), B. Baret (APC/CNRS), A. Coleiro (APC/Universite de Paris), M. Colomer (APC/Universite de Paris), D. Dornic (CPPM/CNRS), A. Kouchner (APC/Universite de Paris), 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 S190720a event using the 90% contour of the bayestar probability map provided by the GW interferometers (GCN#25115 ). The ANTARES visibility at the time of the alert, together with the 50% and 90% contours of the probability map are shown at http://antares.in2p3.fr/GW/S190720a.png . Considering the location probability provided by the LIGO/Virgo collaborations, there is a 41.6% chance that the GW emitter was in the ANTARES **upgoing** field of view at the time of the alert. No up-going muon neutrino candidate events were recorded in the ANTARES sky during a +/-500s time-window centered on the time 2019-07-20 00:08:36 and in the 90% contour of the S190720a event. The expected number of atmospheric background events in the region visible by ANTARES is 3.50e-04 in the +/- 500s time window. An extended search during +/- 1 hour gives no upgoing muon neutrino candidate in coincidence with the 90% contour. In this extended time window, an event (Time = 01:06:24, RA=200.3deg, Dec=7.6 deg) is seen outside the 99% contour, close to the ANTARES horizon. Considering the expected number of atmospheric background events in the ANTARES upgoing field of view, this had a ~10% chance to occur. ANTARES is the largest undersea neutrino detector, installed in the Mediterranean Sea, and it is primarily sensitive to neutrinos in the TeV-PeV energy range. At 10 TeV, the median angular resolution for muon neutrinos is about 0.5 degrees. In the range 1-100 TeV ANTARES has a competitive sensitivity to this position in the sky. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25121 SUBJECT: LIGO/Virgo S190720a: Upper limits from AGILE-GRID observations DATE: 19/07/20 10:12:40 GMT FROM: Claudio Casentini at INAF-IAPS C.Casentini (INAF/IAPS), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), M.Cardillo, G.Piano, A.Ursi (INAF/IAPS), F.Lucarelli, C. Pittori, F.Verrecchia (SSDC, and INAF/OAR), A. Bulgarelli, V. Fioretti, N. Parmiggiani (INAF/OAS-Bologna), M. Pilia (INAF/OA-Cagliari), F. Longo (Univ. Trieste, and INFN Trieste) report on behalf of the AGILE Team: In response to the LIGO-Virgo GW event S190720a at T0 = 2019-07-20 00:08:36.747 (UT) a preliminary analysis of the AGILE exposure near T0 shows that the Gamma-Ray Imaging Detector (GRID) exposure covered about 44% of the 90% c.l. localization region (LR). We performed an analysis of the GRID data in the energy range 50 MeV - 10 GeV near T0. No candidate gamma-ray transient was detected. The following preliminary GRID values of 3-sigma upper limit (UL) are obtained: from 8.68e-07 to 5.09e-06 erg cm^-2 sec^-1, during the time interval (T0 - 2 sec ; T0 + 2 sec); from 3.36e-07 to 2.36e-06 erg cm^-2 sec^-1, during the time interval (T0 ; T0 + 10 sec); from 3.22e-08 to 2.34e-06 erg cm^-2 sec^-1, during the time interval (T0 ; T0 + 100 sec). 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: 25122 SUBJECT: LIGO/Virgo S190720a: Upper limits from Fermi-GBM Observations DATE: 19/07/20 12:31:57 GMT FROM: Joshua Wood at MSFC/Fermi-GBM J. Wood (NASA/MSFC) reports on behalf of the Fermi-GBM Team and the GBM-LIGO/Virgo group: For the LIGO/Virgo detection of GW trigger S190720a (GCN 25115) and using the initial BAYESTAR skymap, Fermi-GBM was observing 73.2% of the localization probability at event time. There was no Fermi-GBM onboard trigger around the event time of S190720a. An automated, blind search for short gamma-ray bursts below the onboard triggering threshold in Fermi-GBM also identified no counterpart candidates. The GBM targeted search, the most sensitive, coherent search for GRB-like signals, was run from +/-30 s around merger time, and also identified no counterpart candidates. We therefore set upper limits on impulsive gamma-ray emission. Using the representative soft, normal, and hard GRB-like templates described in arXiv:1612.02395, we set the following 3 sigma flux upper limits over 10-1000 keV (in units of 10^-8 erg/s/cm^2): Timescale  Soft   Normal   Hard ------------------------------------ 0.128 s:   37.    57.      110. 1.024 s:   13.    17.      40. 8.192 s:   3.2    4.9      9.5 Assuming the median luminosity distance of 1071 Mpc (z=0.215) from the GW detection, we estimate the following intrinsic luminosity upper limits over the 1 keV-10 MeV energy range (in units of 10^48 erg/s): Timescale  Soft   Normal   Hard ------------------------------------ 0.128 s:   78.6   110.     352. 1.024 s:   27.6   32.7     128. 8.192 s:   6.80   9.42     30.4 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25127 SUBJECT: LIGO/Virgo S190720a: No counterpart candidates in the Swift/BAT Observations DATE: 19/07/20 16:32:14 GMT FROM: Amy Lien at GSFC T. Sakamoto (AGU), S. D. Barthelmy (NASA/GSFC), A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL), A. A. Breeveld (MSSL-UCL), A. P. Beardmore (U. Leicester), D. N. Burrows (PSU), S. Campana (INAF-OAB), S. B. Cenko (NASA/GSFC), G. Cusumano (INAF-IASF PA), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB), V. D'Elia (ASI-SSDC), S. Emery (UCL-MSSL), P. A. Evans (U. Leicester), P. Giommi (ASI), C. Gronwall (PSU), D. Hartmann (Clemson U.), J. A. Kennea (PSU), H. A. Krimm (NSF), N. P. M. Kuin (UCL-MSSL), F. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), 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. J. Page (UCL-MSSL), M. Perri (ASDC), J. L. Racusin (NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU), M. H. Siegel (PSU), G. Tagliaferri (INAF-OAB), A. Tohuvavohu (PSU), E. Troja (NASA/GSFC/UMCP) report on behalf of the Swift team: We report the search results in the BAT data within T0 +/- 100 s of the LVC event S190720a (LIGO/VIRGO Collaboration GCN Circ. 25115), where T0 is the LVC trigger time (2019-07-20T00:08:36.704 UTC). The center of the BAT FOV at T0 is RA = 67.774 deg, DEC = 0.195 deg, and the ROLL angle is 53.680 deg. The BAT Field of View (>10% partial coding) covers 0.00% of the integrated LVC localization probability. Within T0 +/- 100 s, no significant detections (signal-to-noise ratio >~ 5 sigma) are found in the BAT raw light curves with time bins of 64 ms, 1 s, and 1.6 s. 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 5-sigma upper limit in the 1-s binned light curve corresponds to a flux upper limit (15-350 keV) of ~ 8.66 x 10^-8 erg/s/cm^2. Note that Swift was slewing from ~T-60 s to ~T+80 s, and thus the bump in the raw light curve around this time is likely due to the background changes during slew. No event data are available within T0 +/- 100 s. BAT retains decreased, but significant, sensitivity to rate increases for gamma-ray events outside of its FOV. About 56.53% of the integrated LVC 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 higher than those within the FOV. The results of the BAT analysis are available at https://swift.gsfc.nasa.gov/results/BATbursts/team_web/S190720a/web/source.html //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25133 SUBJECT: LIGO/Virgo S190720a: No counterpart candidates in KAIT observations DATE: 19/07/20 23:47:40 GMT FROM: Weikang Zheng at UC Berkeley Keto Zhang, Shaunak Modak, Yukei Murakami, Thomas de Jaeger, Benjamin Stahl, WeiKang Zheng, Emily Ma, and Alexei V. Filippenko (UC Berkeley) report on behalf of the Lick/KAIT GW follow-up team: The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at Lick Observatory, observed the 90% region of the gravitational-wavei event S190720a (GCN 25115) detected by LIGO/Virgo. More than one thousand galaxies were selected from the Glade catalog V1.0 (Dalya et al., 2018, MNRAS, 479, 2374; http://aquarius.elte.hu/glade/) according to their priority score. KAIT observed 318 of them based on their priority scores and elevation visibility, with each clear-filter exposure time being 60 s. The first image was taken at 04:22:13, July 20th UT, about 4.2 hours after the trigger, and the last image at 12:09:17 UT. Our typical limiting mag is 19.0. No viable counterparts were identified and the analysis is ongoing. A full list of galaxies observed by KAIT is given below. GladeID UT(July20) RA_J2000 Dec_J2000 ----------------------------------------------- G0791468 04:22:13 12:35:48.0286 +03:12:07.0884 G0125906 04:24:39 13:41:49.1419 +26:22:24.8844 G0640817 04:25:48 13:49:23.5656 +28:06:26.6076 G1812765 04:27:02 14:17:55.68 +35:27:45.612 G0768137 04:28:55 18:13:50.6616 +47:21:14.922 G0913903 04:30:04 18:14:33.5522 +45:47:17.754 G0054767 04:31:13 18:21:52.6978 +45:07:57.6588 G0899681 04:32:22 18:23:52.0385 +45:06:13.2876 G1226063 04:33:32 18:24:36.1157 +43:45:59.4756 G1138290 04:34:41 18:26:50.5298 +45:40:50.6784 G0112846 04:35:50 18:33:17.7247 +44:46:08.7456 G0986625 04:37:00 18:34:51.2182 +44:34:54.6672 G0353251 04:38:09 18:35:37.0973 +44:03:54.5868 G1042660 04:39:18 18:36:08.5106 +44:01:02.5392 G0353888 04:40:28 18:36:48.3473 +45:33:50.3424 G0306366 04:41:37 18:40:35.6616 +44:57:17.046 G0742096 04:42:46 18:44:02.417 +45:33:29.8116 G1464441 04:43:56 18:45:37.705 +44:14:28.95 G1205454 04:45:05 18:46:04.6582 +43:47:58.7616 G1333886 04:46:14 18:48:41.2207 +44:28:29.2656 G1328196 04:47:24 18:55:07.3169 +44:09:52.8228 G1173390 04:48:33 18:59:15 +43:39:52.8228 G0974803 04:49:42 18:59:22.8516 +42:16:18.8256 G1116882 04:50:52 19:01:49.2187 +43:17:06.1656 G1181911 04:52:01 19:02:06.3281 +42:43:21.1512 G1155855 04:53:10 19:02:08.5987 +41:18:57.4848 G1155065 05:14:01 19:03:45.8789 +40:56:28.7592 G1223008 05:15:10 19:04:19.087 +41:24:58.536 G1074284 05:16:19 19:05:58.0445 +40:03:12.15 G1080994 05:17:29 19:07:28.6378 +40:56:31.8084 G0636865 05:18:38 19:08:40.7666 +43:20:36.2364 G0971157 05:19:47 19:08:51.4819 +40:08:13.0236 G1164893 05:20:56 19:09:12.5758 +40:01:46.5528 G0315698 05:22:06 19:09:36.8628 +40:50:35.6316 G1331173 05:23:15 19:09:46.3843 +43:14:56.2524 G0024045 05:24:24 19:10:23.8183 +41:03:22.8636 G0067658 05:25:34 19:11:40.4004 +42:17:21.8076 G1147660 05:26:43 19:12:20.9839 +40:12:39.7728 G1030347 05:27:52 19:12:31.0327 +42:08:18.8196 G1410295 05:29:01 19:15:59.1504 +41:26:05.3592 G1325693 05:30:11 19:17:04.1676 +40:34:28.7112 G1438317 05:31:20 19:19:20.7862 +41:34:55.1208 G1168749 05:32:29 19:21:22.0166 +39:31:07.8132 G1250479 05:33:38 19:22:09.5287 +39:32:07.1952 G0318663 05:34:48 19:22:25.2101 +42:04:12.522 G1256949 05:35:57 19:22:44.004 +41:40:03 G0045746 05:37:06 19:22:44.37 +40:28:21 G1091198 05:38:22 19:23:13.3961 +39:53:38.364 G1161974 05:39:31 19:23:33.816 +39:09:51.6276 G0181691 05:40:40 19:26:30.6518 +40:56:41.3268 G0741517 05:41:50 19:26:40.8178 +41:23:28.4064 G0189318 05:42:59 19:27:10.525 +40:58:17.2236 G1296697 05:44:08 19:27:14.9194 +39:52:00.282 G1001883 05:45:17 19:27:23.4228 +41:26:19.3524 G0895653 05:46:27 19:27:34.9805 +40:23:16.3896 G0134051 05:47:36 19:27:45.3588 +41:44:34.3608 G0925927 05:51:07 19:28:01.8749 +38:26:55.4568 G0852461 05:52:16 19:28:08.2397 +37:54:20.4552 G1335344 05:53:26 19:29:51.6065 +39:13:15.258 G1304158 05:54:35 19:29:56.9604 +38:07:18.2568 G1319161 05:55:44 19:30:24.4337 +39:09:13.1076 G1199779 05:56:54 19:31:57.0703 +39:58:24.528 G1322242 05:58:03 19:32:04.0284 +37:29:05.5644 G1352322 05:59:12 19:32:15.293 +38:29:45.5676 G0062328 06:00:22 19:32:20.5445 +40:25:36.5484 G1120032 06:01:31 19:33:42.7589 +39:07:46.8912 G0922459 06:02:40 19:34:49.021 +40:54:13.698 G0861788 06:03:50 19:38:15.769 +37:43:34.3488 G1337227 06:04:59 19:39:21.8628 +39:54:32.4288 G0411359 06:06:08 19:39:45.9156 +38:37:55.1604 G1255199 06:07:18 19:44:12.4073 +40:33:58.5 G0133863 06:08:27 19:49:10.5175 +39:33:21.5172 G0213208 06:09:38 20:18:41.9532 +32:48:22.7808 G0086608 06:10:48 20:23:38.0419 +29:53:12.498 G1034159 06:11:57 20:24:39.5215 +29:45:25.7004 G0100937 06:13:06 20:25:24.3091 +32:11:26.0268 G0826512 06:14:16 20:28:08.2178 +28:29:57.0948 G1318315 06:15:31 20:28:27.4951 +27:07:46.1928 G1167022 06:16:40 20:30:18.3473 +29:57:51.6924 G0645883 06:17:50 20:30:29.5531 +27:40:42.906 G0519533 06:18:59 20:30:53.4449 +31:29:20.922 G0533475 06:20:08 20:31:18.479 +31:28:17.6484 G1396938 06:21:18 20:34:21.2549 +29:21:14.166 G0885775 06:22:27 20:35:00.7618 +30:06:50.634 G1398480 06:23:34 20:35:57.1582 +29:41:47.2092 G1283352 06:24:44 20:36:50.8154 +29:08:28.6656 G0688454 06:43:46 20:38:31.6699 +25:56:59.6256 G1155077 06:44:55 20:38:49.2041 +27:32:49.974 G0461444 06:46:04 20:40:12.3852 +28:46:50.8728 G1464466 06:47:14 20:40:22.7856 +29:37:50.4192 G1086957 06:48:23 20:41:00.4762 +29:16:33.4056 G0434947 06:49:32 20:41:29.8901 +29:56:40.4268 G1420966 06:50:41 20:41:58.9013 +27:52:02.7804 G1175217 06:51:51 20:43:34.7899 +25:11:12.3756 G1226816 06:53:00 20:43:35.6177 +27:22:22.3788 G1210131 06:54:09 20:43:53.3424 +27:32:19.4244 G0020090 06:55:18 20:44:55.5907 +26:56:46.3308 G1211794 06:56:28 20:45:14.1065 +25:28:07.7268 G1000980 06:57:37 20:45:14.165 +25:58:47.7228 G0916808 06:58:46 20:45:50.9765 +27:22:02.9856 G0776012 06:59:55 20:45:56.9458 +28:31:56.0208 G1405174 07:01:05 20:45:57.876 +24:56:57.03 G1010428 07:02:14 20:46:01.8091 +25:33:47.0448 G1327778 07:03:23 20:46:10.9937 +28:06:54.0684 G1345936 07:04:33 20:46:38.1446 +28:23:15.1692 G1280991 07:05:42 20:47:04.607 +25:29:55.0212 G1078443 07:06:51 20:47:04.7314 +28:41:03.0264 G1183351 07:08:00 20:47:53.2764 +26:44:53.2356 G1203205 07:09:10 20:47:56.4698 +27:59:12.2568 G1103778 07:10:19 20:47:59.502 +28:33:47.2788 G1058065 07:11:28 20:48:30.857 +24:04:50.466 G1373062 07:12:37 20:49:09.8878 +24:51:25.7796 G1415659 07:13:51 20:50:18.2446 +23:56:01.0896 G1425447 07:15:00 20:50:47.5634 +25:35:47.0652 G1250940 07:16:10 20:51:38.3129 +26:55:08.616 G1449925 07:17:19 20:52:02.3364 +25:48:05.6088 G0062132 07:22:46 20:52:04.8194 +23:16:58.0404 G1003347 07:24:02 20:52:28.601 +22:17:38.148 G1144469 07:25:11 20:53:47.7247 +23:59:02.1084 G0442057 07:26:20 20:55:33.4423 +21:50:52.6272 G0864537 07:27:30 20:55:33.9257 +26:26:29.166 G1458202 07:28:39 20:55:35.2001 +24:33:09.1584 G1248511 07:29:48 20:56:46.919 +22:09:19.5696 G1217595 07:30:58 20:57:06.6504 +22:09:46.1052 G0853367 07:32:07 20:57:07.9615 +22:40:31.1016 G1326683 07:33:16 20:57:13.1544 +26:19:38.4132 G1289187 07:34:25 20:57:36.9874 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21:08:46.6699 +21:47:35.97 G0901252 08:27:47 21:09:30.8789 +23:26:36.9096 G1205282 08:28:56 21:09:30.8935 +19:09:11.9124 G0331434 08:30:05 21:09:49.021 +19:43:05.3292 G1408358 08:31:14 21:09:58.6085 +22:44:27.2868 G0203366 08:32:26 21:10:18.5009 +17:43:15.258 G1250816 08:33:35 21:10:42.9274 +21:45:52.308 G1242799 08:36:53 21:10:57.3266 +18:57:59.3496 G0259501 08:38:03 21:11:01.7359 +21:27:12.3552 G1405412 08:39:12 21:11:25.2466 +18:30:02.8224 G1009351 08:40:27 21:11:27.3048 +18:00:25.8264 G0888752 08:41:37 21:11:37.4779 +20:52:20.586 G1080147 08:42:46 21:11:50.5298 +20:59:55.68 G1391634 08:43:55 21:11:54.9535 +18:33:12.6936 G0847078 08:45:05 21:11:58.8427 +20:01:43.7052 G0288824 08:46:14 21:12:05.603 +21:28:07.7052 G1334362 08:47:23 21:12:36.2842 +22:35:47.6844 G1195858 08:48:33 21:12:59.5752 +21:14:36.1932 G1178742 08:49:42 21:13:07.0824 +21:41:38.2092 G0851960 08:50:53 21:13:29.6484 +16:53:48.4692 G1398946 08:52:02 21:13:54.3017 +18:55:22.8684 G0353352 08:53:12 21:13:54.4848 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//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25134 SUBJECT: LIGO/Virgo S190720a: Upper limits from CALET observations DATE: 19/07/21 04:41:47 GMT FROM: Yuta Kawakubo at Louisiana State U./CALET S. Sugita, A. Yoshida, T. Sakamoto, V. Pal'shin (AGU), Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC), M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena), and the CALET collaboration: At the trigger time of the compact binary merger candidate S190720a, T0 = 2019-07-20 00:08:36.704 UT (The LIGO Scientific Collaboration and Virgo Collaboration, GCN Circ. 25115), the CALET Gamma-ray Burst Monitor (CGBM) high voltages were off (from T0-4 min to T0+17 min). The CALET Calorimeter (CAL) was operating in the high energy trigger mode at the trigger time of S190720a. Using the CAL data, we have searched for gamma-ray events in the 10-100 GeV band from -60 sec to +60 sec from the GW trigger time and found no candidates. The 90% upper limit of CAL is 3.0x10^-5 erg/cm^2/s (10-100 GeV) when the summed LIGO-Virgo probability reaches 25%. The CAL FOV was centered at RA = 49.7 deg and DEC = -32.1 deg at T0. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25135 SUBJECT: LIGO/Virgo S190720a: No counterpart candidates in Fermi-LAT observations DATE: 19/07/21 09:15:18 GMT FROM: Magnus Axelsson at Stockholm U. M. Axelsson (KTH and Stockholm Univ.) reports on behalf of the Fermi-LAT Collaboration: We have searched data collected by the Fermi Large Area Telescope (LAT) on July 20, 2019, for possible high-energy (E > 100 MeV) gamma-ray emission in spatial/temporal coincidence with the LIGO/Virgo trigger S190720a (GCN 25115). We define "instantaneous coverage" as the integral over the region of the LIGO probability map that is within the LAT field of view at a given a time, and "cumulative coverage" as the integral of the instantaneous coverage over time. Fermi-LAT had instantaneous coverage of ~45% of the LIGO probability region at the time of the trigger (T0 = 2019-07-20 00:08:36.704 UTC), and reached full coverage at T0+4 ks. We performed a search for a transient counterpart within the observed region of the 90% contour of the LIGO map in a fixed time window from T0 to T0+10 ks. No significant sources were found. We also performed a search which adapted the time interval of the analysis to the exposure of each region of the sky, and no additional excesses were found. Energy flux upper bounds for the fixed time interval between 100 MeV and 1 GeV for this search vary between 1.4E-10 and 3.9E-09 [erg/cm^2/s]. The Fermi-LAT point of contact for this event is Magnus Axelsson (magaxe@kth.se). 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: 25136 SUBJECT: LIGO/Virgo S190720a: No counterpart candidates in CNEOST observations DATE: 19/07/21 14:01:38 GMT FROM: Bin Li at PMO Bin Li, Hai-bin Zhao (PMO),Dong Xu, Zi-pei Zhu, Bang-Yao Yu,Tian-meng Zhang, Xu Zhou,Chen-zhou Cui, Hui-juan Wang(NAOC), Xue-feng Wu, Zhi-ping Jin, Tian-rui Sun, Hao Lu, Ge-tu Zhaori, Ren-quan Hong, Long-fei Hu (PMO), Xiao-feng Wang, Wen-xiong Li (THU),Li-fan Wang (PMO/TAMU), Jin-zhong Liu (XAO), Ji-rong Mao, Jin-ming Bai (YNAO), report on behalf of the CNEOST collaboration. We conducted optical imaging observations for gravitational wave alert with Chinese Near Earth Object Survey Telescope (CNEOST) at Xuyi astronomical station in Jiangsu Province, China (32.75N, 118.47E). The information of observations and preliminary results are listed below. Alert: LIGO/Virgo S190720a (GCN #25115) StartTime (UT): 2019-07-20T13:52:48.017 EndTime (UT): 2019-07-20T14:48:48.031 Skycover (Square Degree): 135.0 Telescope FoV (Square Degree):9.0 #id CentRA(D) CentDEC(D) LimiteMag3_sig 5_sig 10_sig Filter 1 231.208405 43.572357 - 21.204 18.323 SR 2 242.761490 46.336327 21.949 21.134 18.424 SR 3 242.799225 43.565426 22.074 21.229 18.375 SR 4 228.608490 40.790733 - 21.204 18.483 SR 5 221.265320 40.808392 21.856 21.045 18.350 SR 6 231.208405 43.572357 - 21.204 18.323 SR 7 242.761490 46.336327 21.949 21.134 18.424 SR 8 242.799225 43.565426 22.074 21.229 18.375 SR 9 228.608490 40.790733 - 21.204 18.483 SR 10 221.265320 40.808392 21.856 21.045 18.350 SR 11 231.208405 43.572357 - 21.204 18.323 SR 12 242.761490 46.336327 21.949 21.134 18.424 SR 13 242.799225 43.565426 22.074 21.229 18.375 SR 14 228.608490 40.790733 - 21.204 18.483 SR 15 221.265320 40.808392 21.856 21.045 18.350 SR The new resulte will available at http://www.cneost.org/opem/list.php?gdate=2019-07-20 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25138 SUBJECT: LIGO/Virgo S190720a: Updated localization from LIGO and Virgo data DATE: 19/07/22 18:40:13 GMT FROM: John Veitch at U of Glasgow The LIGO Scientific Collaboration and the Virgo Collaboration report: We have re-analyzed LIGO and Virgo data around the time of the compact binary coalescence (CBC) candidate S190720a (GCN 25115). Parameter estimation has been performed using LALInference [1] and a new sky map, LALInference.offline.fits.gz, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S190720a/ This is currently the preferred skymap. For the LALInference.offline.fits.gz sky map, the 90% credible region is 443 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 869 +/- 283 Mpc (a posteriori mean +/- standard deviation). This is the preferred sky map at this time. The LALInference skymap is generated using data from three detectors, while the sky map shared in GCN 25115, was generated from data obtained from two detectors. This partly contributed to the better localization. For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo Public Alerts User Guide . [1] Veitch et al. PRD 91, 042003 (2015) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25147 SUBJECT: LIGO/Virgo S190720a: Thacher Observatory follow-up observations DATE: 19/07/25 03:03:29 GMT FROM: Charles Kilpatrick at UC Santa Cruz J. Swift, Y. Yin (Thacher School Observatory), C. D. Kilpatrick, J. S. Brown, D. A. Coulter, G. Dimitriadis, R. J. Foley, T. Hung, D. O. Jones, C. Rojas-Bravo, M. R. Siebert, K. Siellez (UCSC) report on behalf of the One-Meter Two Hemisphere (1M2H) collaboration: in the process of following up the localization region of LIGO/Virgo event S190720a (GCN 25138), we observed the following fields for 300s each in r-band with the 0.7-m Thacher telescope at the Thacher School Observatory. The localization region was provided by the LIGO/Virgo collaboration in the LALinference map of July 22 17:43:30. All Thacher observations were performed on UT 2019 Jul 23. The approximate center of each image is noted in the table below, and the field of view is a 21 arcmin x 21 arcmin rectangle. We note the approximate 3-sigma limiting magnitude of each image. Comparing our images to PS1 r-band images of the same fields, we did not detect any transient sources. RA (J2000) | Dec (J2000) | MJD | Limiting Magnitude 19:45:50.18 | +35:28:46.2 | 58687.34652 | 20.4 19:55:39.26 | +37:12:37.4 | 58687.35060 | 20.1 19:54:27.91 | +37:33:24.8 | 58687.35459 | 19.8 19:52:21.53 | +38:14:58.9 | 58687.35855 | 20.2 19:55:01.25 | +37:54:12.6 | 58687.36250 | 20.0 19:56:12.58 | +37:33:26.6 | 58687.36645 | 18.8 19:53:15.86 | +37:54:13.0 | 58687.37039 | 19.0 19:57:23.21 | +37:12:40.3 | 58687.37435 | 20.1 19:56:49.44 | +36:51:54.7 | 58687.37831 | 20.5 19:50:35.76 | +38:15:01.4 | 58687.38227 | 20.7 19:51:30.55 | +37:54:15.1 | 58687.38623 | 20.6 19:52:42.91 | +37:33:27.7 | 58687.39022 | 20.6 19:53:54.65 | +37:12:41.8 | 58687.39418 | 20.6 19:55:05.59 | +36:51:56.2 | 58687.39814 | 20.3 19:48:50.04 | +38:15:02.2 | 58687.40209 | 20.2 19:49:45.19 | +37:54:15.8 | 58687.40606 | 19.7 19:50:58.03 | +37:33:29.5 | 58687.41002 | 18.5 19:52:10.22 | +37:12:43.6 | 58687.41397 | 18.9 19:53:21.70 | +36:51:57.2 | 58687.41792 | 17.1 19:54:32.47 | +36:31:12.0 | 58687.42186 | 16.9 Please direct all communication related to this circular to Charlie Kilpatrick (cdkilpat@ucsc.edu). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25227 SUBJECT: LIGO/Virgo S190720a: AstroSat CZTI upper limits DATE: 19/07/31 06:48:35 GMT FROM: Varun Bhalerao at Indian Inst of Tech A. Anumarlapudi (IITB), Aarthy E. (PRL), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), A. R. Rao (TIFR), S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: We have carried a search for X-ray candidates in Astrosat CZTI data in a 100 sec window around the trigger time of the BBH merger event S190720a (UTC 2019-07-20 00:08:36.000, GraceDB event). CZTI is a coded aperture mask instrument that has considerable effective area for about 29% of the entire sky, but is also sensitive to brighter transients from the entire sky. At the time of merger, Astrosat's nominal pointing is (RA=2:27:09.6 (36.790), DEC=33:33:21.1 (33.556)), which is 77.17 deg away from the maximum probability location. At the time of merger event, the Earth-satellite-transient angle corresponding to maximum probability location is ~ 82.09 deg and hence is not occulted by Earth in satellite's frame. In a time interval of 100 sec around the event, 76.74 % of sky locations in the 90% probability region for the event is visible in the satellite's frame and the rest of 23.26 % is occulted by earth. CZTI data were de-trended to remove orbit-wise background variation. We then searched data from three of 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 (+-5) neighbouring orbits. We selected confidence levels such that the probability of a false trigger in a 1000 sec window is 10^-4.We do not find any evidence for any hard X-ray transient in this window, in the CZTI energy range of 20-200 keV. We convert our count rates into flux by assuming that the source spectrum is a power law with alpha = -1.0. We use a detailed mass model of the satellite to calculate the instrument response for every htm grid point that fall in 90% LIGO localization region and calculate flux limit in that direction. We get the following upper limits for source flux in the 20-200 keV band by taking a probability weighted mean of flux limit and are reported here : 0.1 s: flux limit= 5.98e-07 ergs/cm^2/s 1.0 s: flux limit= 1.91e-06 ergs/cm^2/s 10.0 s: flux limit= 2.41e-06 ergs/cm^2/s CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.