//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25162 SUBJECT: LIGO/Virgo S190727h: Upper limits from IceCube neutrino searches DATE: 19/07/27 06:29:06 GMT FROM: Raamis Hussain at IceCube 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 S190727h in a time range of 1000 seconds [3] centered on the alert event time (2019-07-27 05:55:13.986 UTC to 2019-07-27 06:11:53.986 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 S190727h 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 S190727h ranges from 0.035 to 0.983 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: 25163 SUBJECT: LIGO/Virgo S190727h Global MASTER-Net observations report DATE: 19/07/27 06:49:18 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 S190727h errorbox 179 sec after notice time and 738 sec after trigger time at 2019-07-27 06:15:51 UT, with upper limit up to 17.3 mag. The observations began at zenit distance = 82 deg. The sun altitude is -65.7 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=10581 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 814 | 2019-07-27 06:15:51 | MASTER-OAFA | ( 9h 24m 51.16s , -66d 49m 03.06s) | C | 150 | 17.3 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25164 SUBJECT: LIGO/Virgo S190727h: Identification of a GW compact binary merger candidate DATE: 19/07/27 07:31:42 GMT FROM: Shaon Ghosh at UWM The LIGO Scientific Collaboration and the Virgo Collaboration report: We identified the compact binary merger candidate S190727h during real-time processing of data from LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) at 2019-07-27 06:03:33.986 UTC (GPS time: 1248242631.986). The candidate was found by the GstLAL [1], CWB [2], PyCBC Live [3], MBTAOnline [4], and SPIIR [5] analysis pipelines. S190727h is an event of interest because its false alarm rate, as estimated by the online analysis, is 1.4e-10 Hz, or about one in 1e2 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S190727h The classification of the GW signal, in order of descending probability, is BBH (92%), Terrestrial (5%), MassGap (3%), NSBH (<1%), or BNS (<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 [6], distributed via GCN notice about 8 minutes after the candidate For the bayestar.fits.gz sky map, the 90% credible region is 841 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 2022 +/- 516 Mpc (a posteriori mean +/- standard deviation). Note that the preliminary GCN notice incorrectly reported the classification as 99% Terrestrial, and the incorrect skymap was associated with the event. These have now been corrected. For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo Public Alerts User Guide . [1] Messick et al. PRD 95, 042001 (2017) [2] Klimenko et al. PRD 93, 042004 (2016) [3] Nitz et al. PRD 98, 024050 (2018) [4] Adams et al. CQG 33, 175012 (2016) [5] Qi Chu, PhD Thesis, The University of Western Australia (2017) [6] Singer & Price PRD 93, 024013 (2016) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25165 SUBJECT: LIGO/Virgo S190727h: Coverage and upper limits from MAXI/GSC observations DATE: 19/07/27 08:21:48 GMT FROM: Satoshi Sugita at Aoyama Gakuin U. S. Sugita, M. Serino (AGU), N. Kawai, M. Sugizaki (Tokyo Tech), H. Negoro (Nihon U.), M. Nakajima, W. Maruyama, M. Aoki, K. Kobayashi (Nihon U.), 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. Nakahira, Y. Sugawara, S. Ueno, H. Tomida, M. Ishikawa, 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 S190727h at 2019-07-27 06:03:33.985 UTC (GCN 25164). At the trigger time of S190727h, the high-voltage of MAXI/GSC was on. The instantaneous field of view of GSC at the GW trigger time covered 2% of the 90% credible region of the bayestar sky map, in which we found no significant new X-ray source. The first one-orbit (92 min) scan observation with GSC after the event covered 30% of the 90% credible region of the bayestar skymap from 06:03:33 to 07:35:31 UTC (T0+0 to T0+5518 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: 25166 SUBJECT: LIGO/Virgo S190727h: No counterpart candidates in INTEGRAL SPI-ACS prompt observation DATE: 19/07/27 08:48:57 GMT FROM: Alexander Lutovinov at Space Research Inst.,IKI Maeve Doyle (UCD, Ireland), Alexander Lutovinov (IKI, Moscow) 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 INTEGRAL/SPI-ACS realtime data (following [1]) we have performed a search for a prompt gamma-ray counterpart of S190727h (GCN 25164). At the time of the event (2019-07-27 06:03:33 UTC, hereafter T0), INTEGRAL was operating in nominal mode. The peak of the event localization probability was at an angle of 127 deg with respect to the spacecraft pointing axis. This orientation implies strongly suppressed (3.6% of optimal) response of ISGRI, somewhat suppressed (44% of optimal) response of IBIS/Veto, and somewhat suppressed (52% of optimal) response of SPI-ACS. The background within +/-300 seconds around the event was very stable (excess variance 1.1). We have performed a search for any impulsive events in INTEGRAL SPI- ACS (as described in [2]) data. We do not detect any significant counterparts and estimate a 3-sigma upper limit on the 75-2000 keV fluence of 2.1e-07 erg/cm^2 (within the 50% probability containement 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=-0.5 and Ep=600 keV) occurring at any time in the interval within 300 s around T0. For a typical long GRB spectrum (Band function with alpha=-1, beta=-2.5, and Ep=300 keV), the derived peak flux upper limit is ~1.8e-07 (5.9e-08) erg/cm^2/s at 1 s (8 s) time scale in 75-2000 keV energy range. For the mean reported distance 2022.0 Mpc this corresponds to the limit on the total isotropic equivalent energy in 1 s of 1.1e+50 erg for the short GRB spectrum and for a long GRB spectrum isotropic equivalent luminosity in 1 s (8 s) of 8.7e+49 erg/s (2.9e+49 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 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25167 SUBJECT: LIGO/Virgo S190727h: No counterpart candidates in AGILE-MCAL observations DATE: 19/07/27 10:33:03 GMT FROM: Alessandro Ursi at INAF/IAPS A. Ursi (INAF/IAPS), M. Pilia (INAF/OA-Cagliari), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), M. Cardillo, C. Casentini, G. Piano (INAF/IAPS), C.Pittori, F. Lucarelli, F. Verrecchia (SSDC, and INAF/OAR), A. Bulgarelli, V. Fioretti, N. Parmiggiani (INAF/OAS-Bologna), F. Longo (Univ. Trieste, and INFN Trieste) report on behalf of the AGILE Team: In response to the LIGO/Virgo GW event S190727h at T0 = 2019-07-27 06:03:33 UTC (UT), a preliminary analysis of the AGILE minicalorimeter (MCAL) triggered data found no event candidates within a time interval covering -/+ 15 sec from the LIGO/Virgo T0. At the T0, about 80% of the S190727h 90% c.l. localization region was accessible to the AGILE-MCAL. Three-sigma upper limits (ULs) are obtained for a 1 s integration time at different celestial positions within the accessible S190727h localization region, from a minimum of 1.6E-06 erg cm^-2 to a maximum of 7.4E-06 erg cm^-2 (assuming as spectral model a single power law with photon index 1.5). 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: 25168 SUBJECT: LIGO/Virgo S190727h : no neutrino counterpart candidate in ANTARES search DATE: 19/07/27 11:23:27 GMT FROM: Damien Dornic at CPPM,France 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 S190727h event using the 90% contour of the bayestar probability map provided by the GW interferometers (GCN#25164). 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/S190727h.png . Considering the location probability provided by the LIGO/Virgo collaborations, there is a 55.1% 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 2019-07-27 06:03:33 and in the 90% contour of the S190727h event. The expected number of atmospheric background events in the region visible by ANTARES is 2.3e-04 in the +/- 500s time window. An extended search during +/- 1 hour gives no up-going muon neutrino coincidence. The expected number of atmospheric background events in the region visible by ANTARES is 1.7e-03 in this larger time window. 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: 25169 SUBJECT: LIGO/Virgo S190727h: No counterpart candidates in HAWC observations DATE: 19/07/27 13:19:13 GMT FROM: Israel Martinez-Castellanos at UMD/HAWC The HAWC Collaboration (https://www.hawc-observatory.org) reports: The HAWC Collaboration performed a follow-up of the gravitational wave trigger S190727h (GCN #25164). At the time of the trigger the HAWC local zenith was oriented towards (RA, Dec) = (298 deg, 19 deg). 16% of the GW candidate sky location probability (corrected map) 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 5 deg to 44 deg 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 8.9e-05 erg/cm^2 (6.7e-06 erg/cm^2 to 3.9e-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: 25170 SUBJECT: LIGO/Virgo S190727h: Upper limits from Fermi-GBM Observations DATE: 19/07/27 14:13:25 GMT FROM: C. Michelle Hui at MSFC/Fermi-GBM C. M. Hui(NASA/MSFC) reports on behalf of the Fermi-GBM Team and the GBM-LIGO/Virgo group For S190727h and using the initial BAYESTAR skymap, Fermi-GBM was observing 65% of the localization probability at event time. There was no Fermi-GBM onboard trigger around the event time of the LIGO/Virgo detection of GW trigger S190727h (GCN 25164). 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. Part of the LVC localization region is behind the Earth for Fermi, located at RA=288.0, Dec=21.0 with a radius of 67.2 degrees. 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^-7 erg/s/cm^2): Timescale Soft Normal Hard ------------------------------------ 0.128 s: 3.7 5.7 14.0 1.024 s: 1.2 2.8 5.8 8.192 s: 0.6 1.1 1.9 Assuming the median luminosity distance of 2022 Mpc from the GW detection, we estimate the following intrinsic luminosity upper limits over the 1 keV-10 MeV energy range (in units of 10^50 erg/s): Timescale Soft Normal Hard ------------------------------------ 0.128 s: 3.4 4.5 18.8 1.024 s: 1.1 2.2 7.8 8.192 s: 0.5 0.9 2.5 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25171 SUBJECT: LIGO/Virgo S190727h: possible counterpart candidate in SPI-ACS/INTEGRAL DATE: 19/07/27 14:26:04 GMT FROM: Alexei Pozanenko at IKI, Moscow P. Minaev (IKI), A. Pozanenko (IKI), I. Chelovekov (IKI), S. Grebenev (IKI) on behalf of IKI GRB FuN collaboration report: Using INTEGRAL/SPI-ACS public data we performed a search for counterpart of S190727h (LVC, GCN 25164). We found only one significant excess (3.6 sigma) at 4 sec and duration of 0.15 s after event time 2019-07-27T06:03:33.98. No more credible emission found within 100 s after the trigger time of S190727h. The background excess variance 1.25 around +/-500 sec around event time which is somewhat higher than usual. The significance of the excess will be further investigated by chance coincidence analysis. The fluence of the pulse is 574 +/- 160 counts which corresponds to (5.7 +/ -1.6)*10^-8 erg/cm2 at the angle of 127 degrees toward most probable area of localization. Assuming source distance of 2022.0 Mpc this corresponds to the Eiso = (2.4 +/- 0.7)*10^49 erg. The light curve of SPI-ACS can be found at http://grb.rssi.ru/S190727h/S190727h_SPI-ACS_0.15s_LC.png //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25172 SUBJECT: LIGO/Virgo S190727h: No counterpart candidates in Fermi-LAT observations DATE: 19/07/27 15:46:46 GMT FROM: Milos Kovacevic at INFN Perugia M. Kovacevic (INFN Perugia), E. Bissaldi (Politecnico and INFN Bari), S. Cutini (INFN Perugia) and F. Longo (University and INFN, Trieste) report on behalf of the Fermi-LAT Collaboration: We have searched data collected by the Fermi Large Area Telescope (LAT) on July 27, 2019, for possible high-energy (E > 100 MeV) gamma-ray emission in spatial/temporal coincidence with the LIGO/Virgo trigger S190727h (GCN 25164). 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 ~69% of the LIGO probability region at the time of the trigger (T0 = 2019-07-27 06:03:33.986 UTC), and reached full coverage at T0+5.4 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 1.5E-10 and 7.3E-09 [erg/cm^2/s]. The Fermi-LAT point of contact for this event is Milos Kovacevic (milos.kovacevic@pg.infn.it). 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: 25174 SUBJECT: LIGO/Virgo S190727h: No counterpart candidates in the Swift/BAT Observations DATE: 19/07/27 16:15:33 GMT FROM: Amy Lien at GSFC S. D. Barthelmy (NASA/GSFC), A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL), T. Sakamoto (AGU), A. P. Beardmore (U. Leicester), M. G. Bernardini (INAF-OAB), A. A. Breeveld (MSSL-UCL), 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 S190727h (LIGO/VIRGO Collaboration GCN Circ. 25164), where T0 is the LVC trigger time (2019-07-27T06:03:33.985 UTC). The center of the BAT FOV at T0 is RA = 171.271 deg, DEC = -3.729 deg, and the ROLL angle is 287.727 deg. The BAT Field of View (>10% partial coding) covers 0.05% of the integrated LVC localization probability, and 0.04% of the galaxy convolved probability (Evans et al. 2016). 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 ~ 6.42 x 10^-8 erg/s/cm^2. Also, there is no significant excess in the BAT raw light curves around the time of the possible candidate reported by INTEGRAL at ~T0+4 s (Minaev et al. GCN 25171), though the BAT FOV may cover different part of the sky than the INTEGRAL FOV around this time. Event data are available from T0-14.342 to T0-11.182. No significant detections are found in the 15-350 keV images made using the full event data range. BAT retains decreased, but significant, sensitivity to rate increases for gamma-ray events outside of its FOV. About 59.13% 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/S190727h/web/source.html //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25179 SUBJECT: LIGO/Virgo S190727h: No counterpart candidates in KAIT observations DATE: 19/07/28 02:32:48 GMT FROM: Weikang Zheng at UC Berkeley Yukei Murakami, Shaunak Modak, Keto Zhang, Thomas de Jaeger, Benjamin Stahl, Andrew Hoffman, Nachiket Girish, WeiKang Zheng, and Alexei V. Filippenko (UC Berkeley) report on behalf of 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 S190727h (GCN 25164) 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 166 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 08:02:37, July 27th UT, about 1.98 hours after the trigger, and the last image at 12:30:34 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 ----------------------------------------------- G0818262 08:02:37 00:00:06.371 +53:19:13.62 G1203758 08:03:52 00:00:13.9702 +51:55:08.6556 G1076663 08:05:02 00:00:17.5322 +53:09:52.6572 G0811321 08:06:11 00:00:22.105 +53:17:40.6464 G1300914 08:07:20 00:01:38.6659 +51:52:37.2648 G0244363 08:08:30 00:01:54.217 +53:15:26.2836 G0009676 08:09:39 00:02:48.8976 +53:53:13.974 G0567217 08:10:46 00:03:13.3178 +53:52:14.9772 G0776614 08:11:56 00:03:27.0797 +56:21:05.1588 G0053858 08:13:05 00:03:31.9903 +53:26:30.876 G0749731 08:14:14 00:03:38.3064 +51:46:40.4436 G0612592 08:15:24 00:03:51.3511 +51:43:37.5348 G0876890 08:16:33 00:05:13.4796 +53:39:05.8284 G0516166 08:17:42 00:05:27.7771 +53:44:51.8424 G0573585 08:18:52 00:05:34.2828 +53:37:52.8096 G0323132 08:20:01 00:06:09.7752 +54:09:57.7944 G1012532 08:21:10 00:07:02.6165 +54:35:34.944 G1024091 08:22:19 00:08:25.2883 +54:00:01.8 G0668270 08:23:29 00:08:31.0214 +53:01:49.1628 G1337350 08:24:38 00:08:36.4001 +55:41:11.814 G1282948 08:25:47 00:09:26.4521 +52:44:31.8336 G0279085 08:26:57 00:10:38.9335 +53:25:04.0404 G1437233 08:28:06 00:10:42.0216 +54:20:54.2112 G0568420 08:29:15 00:11:21.7159 +52:31:43.7124 G1013223 08:30:25 00:11:36.8186 +53:30:52.2 G0513356 08:31:34 00:12:04.5228 +52:33:24.264 G0851338 08:32:43 00:12:18.9274 +52:33:46.098 G1334038 08:33:53 00:14:10.3277 +52:53:48.5952 G1413339 08:35:02 00:20:37.2701 +52:10:10.4124 G0579706 08:36:11 00:27:28.434 +52:22:11.5716 G1135340 08:50:58 00:45:45.6506 +51:08:44.9664 G0962533 08:52:07 00:45:52.5593 +51:08:24.0252 G0671015 08:53:17 00:46:19.3781 +51:13:02.8308 G1132698 08:54:26 00:46:55.2682 +51:19:42.9924 G1447824 09:15:58 23:23:42.539 +50:55:52.9464 G0829771 09:17:07 23:23:50.2222 +51:50:17.0088 G0869566 09:18:14 23:24:59.5531 +51:28:13.5984 G0513188 09:19:24 23:26:29.0186 +54:05:39.3828 G1066675 09:20:33 23:26:32.0801 +54:11:17.3904 G1418129 09:21:42 23:27:18.9991 +52:22:13.1484 G1059922 09:22:52 23:27:43.2787 +50:09:39.294 G0315576 09:24:01 23:28:22.7563 +53:31:18.5376 G0302926 09:25:10 23:29:07.0531 +51:04:19.3728 G1317711 09:26:19 23:30:26.3378 +49:43:42.7944 G1443037 09:27:29 23:30:37.8955 +49:10:51.834 G0952589 09:28:46 23:32:01.0474 +48:58:50.8404 G1301847 09:29:56 23:32:27.0336 +50:12:14.5872 G0427950 09:31:05 23:32:54.4116 +53:26:57.7104 G0280991 09:32:14 23:32:59.5092 +50:34:22.6848 G0953905 09:33:24 23:33:04.1234 +50:34:15.6504 G0267103 09:34:33 23:35:01.919 +51:32:56.4144 G1021218 09:35:42 23:35:31.1426 +51:18:39.7404 G0108795 09:36:52 23:35:45.7543 +51:18:59.7348 G1026896 09:38:01 23:35:52.4707 +51:37:47.6868 G1414332 09:39:10 23:35:54.126 +49:04:22.6848 G0116210 09:40:22 23:36:46.5382 +54:57:35.7768 G0547479 09:41:31 23:36:54.2724 +50:32:05.8632 G1059481 09:42:38 23:37:19.519 +51:15:18.882 G1050452 09:43:47 23:37:29.663 +51:29:15.4212 G0902803 09:44:57 23:37:53.5474 +50:42:15.66 G0926195 09:46:06 23:38:15.0806 +50:59:17.4264 G1273061 09:47:15 23:39:34.38 +51:41:53.2032 G1277843 09:48:25 23:39:52.4633 +50:11:32.5356 G1045359 09:49:34 23:39:54.7339 +52:14:50.55 G0293944 10:03:26 23:40:04.6363 +50:24:48.5928 G0984243 10:04:43 23:40:15.4176 +55:38:30.4512 G1248577 10:05:52 23:40:49.9073 +53:18:26.7768 G0426389 10:07:12 23:40:53.1665 +50:47:32.7804 G0438847 10:08:21 23:41:17.9443 +50:57:54.2196 G1308375 10:09:31 23:41:35.8008 +51:33:50.2452 G1018485 10:10:40 23:41:38.4302 +51:51:15.2388 G0590548 10:11:47 23:42:26.3014 +51:18:56.4264 G0604212 10:12:57 23:42:40.481 +51:08:56.9688 G0287295 10:14:14 23:42:57.5244 +54:26:17.1852 G1285587 10:15:23 23:43:04.4825 +50:28:57.1188 G1367761 10:16:33 23:43:15.7764 +51:54:15.3576 G0155712 10:17:46 23:43:25.8838 +55:37:05.0196 G0268433 10:19:02 23:44:03.0835 +53:24:15.948 G0063108 10:20:13 23:44:06.8261 +54:34:04.4184 G0324054 10:21:29 23:44:33.4058 +52:35:30.0984 G0018188 10:22:40 23:46:05.713 +53:13:56.4708 G1181955 10:23:54 23:47:04.7974 +51:42:17.9532 G1131412 10:25:03 23:47:06.8114 +51:25:15.9636 G0951344 10:26:12 23:47:35.039 +50:56:25.6848 G0204034 10:27:24 23:47:37.6757 +52:59:07.7316 G0706125 10:28:35 23:47:42.7661 +52:13:30.7776 G1440932 10:29:47 23:47:49.4018 +53:25:51.834 G0102701 10:31:06 23:48:45.6226 +56:10:54.1812 G0021044 10:32:28 23:49:12.605 +51:38:29.0256 G0512499 10:33:51 23:49:20.1782 +57:03:30.4416 G1401133 10:35:13 23:49:24.463 +53:09:23.1192 G0941661 10:36:28 23:49:30.2198 +51:31:16.1364 G1261385 10:37:40 23:49:50.3393 +51:36:49.0212 G1249665 10:38:51 23:50:14.8315 +50:59:15.0936 G0103824 10:51:18 23:50:20.9472 +54:14:23.7732 G1188758 10:52:32 23:51:11.3525 +53:19:39.918 G1395349 10:53:43 23:51:14.7583 +53:53:09.9348 G1422602 10:54:55 23:51:21.5918 +53:24:51.2856 G0853098 10:56:06 23:51:24.5508 +54:15:55.9332 G0106206 10:57:24 23:51:35.2661 +52:21:34.3404 G0525892 10:58:39 23:52:09.1039 +53:54:25.6464 G0176297 10:59:57 23:52:13.3961 +51:33:25.7184 G0981419 11:01:08 23:52:14.1576 +51:20:57.714 G0619320 11:02:20 23:52:33.1421 +52:14:59.6688 G0972728 11:03:31 23:52:58.5646 +51:58:12.2664 G0615425 11:04:43 23:53:06.2402 +51:56:17.2644 G0528754 11:05:56 23:54:03.5155 +52:57:55.1808 G0657587 11:07:12 23:54:12.2534 +54:07:04.9656 G1251903 11:08:23 23:54:49.5336 +53:39:26.3736 G1290038 11:09:35 23:56:03.8378 +53:43:35.0616 G0576737 11:10:50 23:56:06.3574 +52:03:24.0588 G1153343 11:12:02 23:56:12.107 +52:31:55.0272 G1196753 11:13:13 23:56:12.4366 +52:32:04.0344 G1303397 11:14:25 23:56:53.3863 +51:43:31.9188 G1309285 11:15:50 23:56:57.6708 +56:03:05.3136 G0090940 11:17:06 23:56:57.942 +56:37:49.3068 G1223297 11:18:32 23:57:14.3189 +53:58:55.29 G1136725 11:19:47 23:58:12.6854 +52:35:04.7472 G0646306 11:21:00 23:58:30.5494 +52:02:41.9928 G1298568 11:22:12 23:58:55.9716 +51:48:31.0464 G0251071 11:23:27 23:58:57.7882 +53:54:29.2572 G0555350 11:24:41 23:59:20.4274 +53:14:30.5988 G0775841 11:25:56 23:59:43.8574 +51:54:16.7184 G1217402 11:27:20 23:40:28.4839 +53:04:48.666 G0831995 11:36:27 00:00:46.6106 +56:00:51.2928 G1334953 11:37:48 00:01:16.6786 +54:44:31.6428 G0940500 11:39:06 00:01:39.7975 +53:30:30.2796 G0268031 11:40:17 00:06:15.0806 +52:25:01.9668 G1438450 11:41:31 00:06:41.3861 +50:58:14.2428 G0855370 11:42:42 00:07:17.4802 +51:36:46.3572 G0441162 11:43:54 00:07:26.6489 +53:07:08.4252 G0905720 11:45:05 00:09:42.2878 +52:17:28.878 G0915466 11:46:17 00:10:03.7836 +51:43:12.7308 G0265819 11:47:28 00:10:27.5138 +52:18:44.1072 G1192960 11:48:39 00:11:07.9397 +52:03:13.7592 G0829815 11:49:51 00:11:28.5958 +52:28:09.6708 G1197851 11:51:04 00:11:31.3956 +50:57:04.644 G1142242 11:52:16 00:11:45.2431 +50:58:57.2664 G1385352 11:53:28 00:12:01.1513 +52:45:22.2732 G1172552 11:54:43 00:17:25.7508 +53:30:37.4364 G0972983 11:55:55 00:18:32.1881 +52:59:36.312 G1397419 11:57:06 00:19:23.0102 +53:32:23.1936 G1342514 11:58:18 00:19:31.0169 +53:29:00.2472 G1369289 11:59:31 00:21:13.9414 +52:10:06.3624 G1369269 12:00:43 00:21:47.2949 +52:19:04.2672 G0985731 12:01:54 00:22:56.0398 +51:31:22.8108 G1323469 12:03:06 00:23:38.1406 +53:13:05.0556 G0906819 12:04:17 00:23:40.0896 +52:55:53.0544 G1392490 12:05:29 00:24:21.5189 +52:04:37.02 G0381897 12:06:40 00:24:40.8425 +51:57:08.874 G1236402 12:07:52 00:25:40.2209 +52:45:25.5312 G0960409 12:09:03 00:26:48.4402 +52:38:57.5196 G0916498 12:10:15 00:27:18.9343 +52:22:04.6344 G0932257 12:11:27 00:27:29.9335 +52:33:14.6628 G0919796 12:17:27 00:27:37.2456 +52:05:47.7024 G0905270 12:18:39 00:28:11.7324 +52:14:15.5184 G0685045 12:19:50 00:29:32.4974 +51:50:57.5484 G1108582 12:21:02 00:29:37.6322 +52:01:11.5212 G1404391 12:22:13 00:30:31.9464 +51:39:50.2812 G1090367 12:23:25 00:32:07.0378 +52:03:32.2704 G1051791 12:24:36 00:32:29.6472 +51:17:34.2888 G1292533 12:25:48 00:32:42.6626 +51:37:08.562 G1290366 12:27:00 00:33:48.5784 +51:40:30.6552 G0941304 12:28:11 00:34:22.0123 +50:58:11.0424 G1072481 12:29:22 00:35:07.3786 +49:29:08.214 G0248155 12:30:34 00:36:43.4292 +49:25:29.64 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25184 SUBJECT: LIGO/Virgo S190727h: No transient candidates in CALET observations DATE: 19/07/28 07:22:48 GMT FROM: Yuta Kawakubo at Louisiana State U./CALET K. Yamaoka (Nagoya U), A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU), Y. Kawakubo (LSU), 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: The CALET Gamma-ray Burst Monitor (CGBM) was operating at the trigger time of S190727h T0 = 2019-07-27 06:03:33.986 UT (The LIGO Scientific Collaboration and Virgo Collaboration, GCN Circ. 25164). No CGBM on-board trigger occurred around the event time. Based on the LIGO-Virgo localization sky map, the summed LIGO probabilities inside the CGBM HXM (7 - 3000 keV) and SGM (40 keV - 28 MeV) fields of view are 0 % and 34 %, respectively (and 35 % credible region of the initial localization map was above the horizon). The HXM and SGM fields of view were centered at RA = 191.8 deg, Dec = 45.3 deg and RA = 201.2 deg, Dec = 38.2 deg at T0, respectively. Based on the analysis of the light curve data with 0.125 sec time resolution from T0-60 sec to T0+60 sec, we found no significant excess (signal-to-noise ratio >= 7) around the trigger time in either the HXM or the SGM data. The CALET Calorimeter (CAL) was operating in the high energy trigger mode at the trigger time of S190727h, but the CAL FOV does not have any overlap with LVC probability significance map. The CAL FOV was centered at RA= 201.1 deg, DEC= 38.2 deg at T0. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25223 SUBJECT: LIGO/Virgo S190727h: Gaia Photometric Alerts transient candidate DATE: 19/07/30 14:23:36 GMT FROM: Deepak Eappachen at SRON Netherlands Z. Kostrzewa-Rutkowska, D. Eappachen (SRON/RU), S. Hodgkin, A. Delgado, D.L. Harrison, M.van Leeuwen, G. Rixon, A. Yoldas (IoA Cambridge), P.G. Jonker (SRON/RU) on behalf of Gaia Alerts team report the discovery of a transient candidate within the probability skymap of S190727h (LIGO/VIRGO Collaboration GCN 25164): --------------------------------------------------------------------------- Name TNSid Date [TCB] RaDeg DecDeg AlertMag URL ---------------------------------------------------------------------------- Gaia19dfl AT2019lyg 2019-07-27T17:34:08 112.70158 -56.68758 18.69 http://gsaweb.ast.cam.ac.uk/alerts/alert/Gaia19dfl/ --------------------------------------------------------------------------- Note: blue transient observed within 12 hours from S190727h Acknowledgements: This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. ZKR, DE, and PGJ acknowledge support from the European Research Council under ERC Consolidator Grant agreement no 647208. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25228 SUBJECT: LIGO/Virgo S190727h: AstroSat CZTI upper limits DATE: 19/07/31 06:49:46 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 S190727h (UTC 2019-07-27 06:03:33.000, 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=17:32:08.0 (263.033), DEC=-33:47:40.4 (-33.795)), which is 67.51 deg away from the maximum probability location. At the time of merger event, the Earth-satellite-transient angle corresponding to maximum probability location is ~ 103.71 deg and hence is not occulted by Earth in satellite's frame. In a time interval of 100 sec around the event, 81.33 % of sky locations in the 90% probability region for the event is visible in the satellite's frame and the rest of 18.67 % 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= 3.32e-06 ergs/cm^2/s 1.0 s: flux limit= 1.15e-05 ergs/cm^2/s 10.0 s: flux limit= 1.39e-05 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. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25249 SUBJECT: LIGO/Virgo S190727h: Updated sky localization DATE: 19/08/01 14:52:00 GMT FROM: Shaon Ghosh at UWM The LIGO Scientific Collaboration and the Virgo Collaboration report: We have conducted further analysis of the LIGO and Virgo data around the time of the compact binary coalescence (CBC) candidate S190727h (GCN 25164). Parameter estimation has been performed using LALInference [1] and a new sky map, LALInference.fits.gz, distributed via GCN Notice, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S190727h LALInference.fits.gz is the preferred sky map at this time. The 90% credible region is 151 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 2839 +/- 655 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] Veitch et al. PRD 91, 042003 (2015)