//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25501 SUBJECT: LIGO/Virgo S190828l: No counterpart candidates in HAWC observations DATE: 19/08/28 08:40:30 GMT FROM: Edna L. Ruiz-Velasco at MPIK The HAWC Collaboration (https://www.hawc-observatory.org) reports: The HAWC Collaboration performed a follow-up of the gravitational wave trigger S190828l. At the time of the trigger the HAWC local zenith was oriented towards (RA, Dec) = (342.5 deg, 18.9 deg). 21% 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 0.9 deg to 45.0 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 1.1e-04 erg/cm^2 (6.5e-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: 25503 SUBJECT: LIGO/Virgo S190828l: Identification of a GW compact binary merger candidate DATE: 19/08/28 08:50:49 GMT FROM: Qi Chu at LSC The LIGO Scientific Collaboration and the Virgo Collaboration report: We identified the compact binary merger candidate S190828l during real-time processing of data from LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) at 2019-08-28 06:55:09.887 UTC (GPS time: 1251010527.887). The candidate was found by the GstLAL [1], MBTAOnline [2], SPIIR [3], and PyCBC Live [4] analysis pipelines. Note that S190828l and S190828j (GCN 25497) are distinct events that occurred 21 minutes apart. S190828l is an event of interest because its false alarm rate, as estimated by the online analysis, is 4.6e-11 Hz, or about one in 700 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S190828l The classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), BNS (<1%), MassGap (<1%), or NSBH (<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 22 minutes after the candidate For the bayestar.fits.gz sky map, the 90% credible region is 948 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1609 +/- 426 Mpc (a posteriori mean +/- standard deviation). The localizations of S190828j and S190828l strongly resemble each other. This is not unexpected for events occurring at similar times because the detector sensitivity antenna patterns rotate with the Earth. The two localizations are definitely disjoint: their prevailing triangulation annuli are separated by over 10 degrees. 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] Adams et al. CQG 33, 175012 (2016) [3] Qi Chu, PhD Thesis, The University of Western Australia (2017) [4] Nitz et al. PRD 98, 024050 (2018) [5] Singer & Price PRD 93, 024013 (2016) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25505 SUBJECT: LIGO/Virgo S190828l: No counterpart candidates in INTEGRAL SPI-ACS prompt observation DATE: 19/08/28 08:59:07 GMT FROM: Enrico Bozzo at ISDC E. Bozzo (ISDC/UniGE, Switzerland), S. Schanne (CEA, France) 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 S190828l (GCN 25503). At the time of the event (2019-08-28 06:55:09 UTC, hereafter T0), INTEGRAL was operating in nominal mode. The peak of the event localization probability was at an angle of 87 deg with respect to the spacecraft pointing axis. This orientation implies strongly suppressed (9.1% of optimal) response of ISGRI, strongly suppressed (28% of optimal) response of IBIS/Veto, and near-optimal (83% 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 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=-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 ~1.5e-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 1609.0 Mpc this corresponds to the limit on the total isotropic equivalent energy in 1 s of 5.5e+49 erg for the short GRB spectrum and for a long GRB spectrum isotropic equivalent luminosity in 1 s (8 s) of 4.7e+49 erg/s (1.7e+49 erg/s) We report for completeness and in order of FAP, all excesses identified in the search region. We find: 6 likely background excesses: scale | T | S/N | luminosity ( x 1e+50 erg/s) | FAP 1.1 | -94.7 | 3.9 | 10.1 +/- 3.08 +/- 5.79 | 0.32 0.4 | -31.2 | 3.7 | 16.1 +/- 5.12 +/- 9.27 | 0.368 0.45 | 51.4 | 3.7 | 15.2 +/- 4.83 +/- 8.74 | 0.594 0.8 | -33.8 | 3.1 | 9.37 +/- 3.61 +/- 5.4 | 0.809 4.3 | 249 | 3.2 | 4.16 +/- 1.55 +/- 2.4 | 0.936 1.3 | -71.8 | 3.1 | 7.53 +/- 2.83 +/- 4.34 | 0.957 Note that FAP estimates (especially at timescales above 2s) may be possibly further affected by enhanced non-stationary local background noise. This list excludes any excesses for which FAP is close to unity. 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: 25507 SUBJECT: LIGO/Virgo S190828l : no neutrino counterpart candidate in ANTARES search DATE: 19/08/28 09:28:35 GMT FROM: Alexis Coleiro at APC/U. Paris Diderot 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 S190828l event using the 90% contour of the Initial bayestar probability map provided by the GW interferometers (GCN#25503 ). 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/S190828l_Initial.png . Considering the location probability provided by the LIGO/Virgo collaborations, there is a 56.8% 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 2019-08-28 06:55:09 and in the 90% contour of the S190828l event. The expected number of atmospheric background events in the region visible by ANTARES is 2.80e-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 2.02e-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: 25510 SUBJECT: LIGO/Virgo S190828l: No counterpart candidates in AGILE-MCAL observations DATE: 19/08/28 10:03:25 GMT FROM: Francesco Longo at U of Trieste,INFN Trieste F. Longo (Univ. Trieste, and INFN Trieste), F. Verrecchia, C. Pittori (SSDC, and INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), M. Cardillo, C. Casentini, G. Piano, A. Ursi (INAF/IAPS), F. Lucarelli (SSDC, and INAF/OAR), A. Bulgarelli, V. Fioretti, N. Parmiggiani (INAF/OAS-Bologna), M. Pilia (INAF/OA-Cagliari), report on behalf of the AGILE Team: In response to the LIGO/Virgo GW event S190828l at T0 = 2019-08-28 06:55:09 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 50% of the S190828l 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 S190828l localization region, from a minimum of 1.83E-06 erg cm^-2 to a maximum of 6.33E-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: 25511 SUBJECT: LIGO/Virgo S190828l: Coverage and upper limits from MAXI/GSC observations DATE: 19/08/28 10:16:23 GMT FROM: Hitoshi Negoro at Nihon U H. Negoro (Nihon U.), M. Serino, S. Sugita (AGU), N. Kawai, M. Sugizaki (Tokyo Tech), 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 S190828l at 2019-08-28 06:55:09.886 UTC (GCN 25503). At the trigger time of S190828l, the high-voltage of MAXI/GSC was off, and it was turned on at T0+387 sec (+6.5 min). The first one-orbit (92 min) scan observation with GSC after the event covered 94% of the 90% credible region of the bayestar skymap from 07:01:46 to 08:10:26 UTC (T0+397 to T0+4517 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: 25512 SUBJECT: LIGO/Virgo S190828l Global MASTER-Net observations report DATE: 19/08/28 10:43:38 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 S190828l errorbox 1606 sec after notice time and 3022 sec after trigger time at 2019-08-28 07:45:31 UT, with upper limit up to 16.6 mag. The observations began at zenit distance = 84 deg. The sun altitude is -41.4 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=10739 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 3113 | 2019-08-28 07:45:31 | MASTER-OAFA | (09h 43m 48.516s , -49d 48m 33.56s) | C | 180 | 14.8 | 6722 | 2019-08-28 08:45:40 | MASTER-OAFA | (09h 37m 17.654s , -51d 55m 37.22s) | C | 180 | 16.6 | 6943 | 2019-08-28 08:49:22 | MASTER-OAFA | (09h 37m 19.541s , -51d 55m 31.84s) | C | 180 | 15.8 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25514 SUBJECT: LIGO/Virgo S190828l: Upper limits from IceCube neutrino searches DATE: 19/08/28 11:11:45 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 S190828l in a time range of 1000 seconds [3] centered on the alert event time (2019-08-28 06:46:49.887 UTC to 2019-08-28 07:03:29.887 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 S190828l calculated from the map circulated in the 2-Initial 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 S190828l ranges from 0.030 to 1.000 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: 25515 SUBJECT: LIGO/Virgo S190828l: Upper limits from AGILE-GRID observations DATE: 19/08/28 11:42:48 GMT FROM: Francesco Verrecchia at ASDC F. Longo (Univ. Trieste, and INFN Trieste), F. Verrecchia, C. Pittori (SSDC, and INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), M. Cardillo, C. Casentini, G. Piano, A. Ursi (INAF/IAPS), F. Lucarelli (SSDC, and INAF/OAR), A. Bulgarelli, V. Fioretti, N. Parmiggiani (INAF/OAS-Bologna), M. Pilia (INAF/OA-Cagliari), report on behalf of the AGILE Team: In response to the LIGO-Virgo GW event S190828l at T0 = 2019-08-28 06:55:09.887 UT a preliminary analysis of the AGILE exposure at T0 shows that the Gamma-Ray Imaging Detector (GRID) exposure covered less than 10% of the 90% c.l. localization region (LR; around 40% of 90% c.l. LR is occulted by Earth). We performed an analysis of the GRID data in the energy range 50 MeV - 10 GeV over time intervals before and after T0, where good exposure of the S190828l 90% c.l. LR was available. No candidate gamma-ray transient was detected. The following preliminary GRID values of 3-sigma upper limit (UL) are obtained: from 3e-08 to 2.e-07 erg cm^-2 s^-1, with exposure of about 50% of the LR over the time interval ( T0 - 100s ; T0 + 0s ); from 8e-08 to 7e-08 erg cm^-2 s^-1, with exposure of about 50% of the LR over the time interval ( T0 + 200s ; T0 + 300s ); 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: 25523 SUBJECT: LIGO/Virgo S190828l: Upper limits from Fermi-GBM Observations DATE: 19/08/28 16:15:56 GMT FROM: Peter Veres at UAH P. Veres (UAH) reports on behalf of the Fermi-GBM Team and the GBM-LIGO/Virgo group: For S190828l and using the initial bayestar skymap, Fermi-GBM was observing 29% 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 S190828l (GCN 25503). 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 erg/s/cm^2): Timescale Soft Normal Hard ------------------------------------ 0.128 s: 1.8e-07 2.3e-07 5.0e-07 1.024 s: 6.4e-08 1.0e-07 2.1e-07 8.192 s: 2.7e-08 3.5e-08 7.7e-08 Assuming the median luminosity distance of 1609 Mpc (z=0.31) from the GW detection, we estimate the following intrinsic luminosity upper limits over the 1 keV-10 MeV energy range (in units of 10^49 erg/s): Timescale Soft Normal Hard ------------------------------------ 0.128 s: 8.9 10 37 1.024 s: 3.2 4.4 16 8.192 s: 1.3 1.5 5.7 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25533 SUBJECT: LIGO/Virgo S190828l: no counterpart candidates in the Swift/BAT Observations DATE: 19/08/28 22:57:23 GMT FROM: Amy Lien at GSFC A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (NASA/GSFC), 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), D. B. Malesani (DTU Space), 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 S190828l (LIGO/VIRGO Collaboration GCN Circ. 25503), where T0 is the LVC trigger time (2019-08-28T06:55:09.887 UTC). The center of the BAT FOV at T0 is RA = 323.901 deg, DEC = 47.455 deg, The roll angle is 351.941 deg. The BAT Field of View (>10% partial coding) covers 21.29% of the integrated LVC localization probability, and 21.76% 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 ~ 7.29 x 10^-8 erg/s/cm^2. 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 4.86% 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/S190828l/web/source_public.html //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25537 SUBJECT: LIGO/Virgo S190828l: No transient candidates in CALET observations DATE: 19/08/29 04:17:41 GMT FROM: Yuta Kawakubo at Louisiana State U./CALET Y. Shimizu (Kanagawa U), A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU), Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), Y. Asaoka, S. Ozawa, S. Torii (Waseda U), 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 S190828l T0 = 2019-08-28 06:55:09.887 UT (The LIGO Scientific Collaboration and Virgo Collaboration, GCN Circ. 25503). 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 5 % and 41 %, respectively (and 79 % credible region of the initial localization map was above the horizon). The HXM and SGM fields of view were centered at RA = 109.4 deg, Dec = 60.9 deg and RA = 107.0 deg, Dec = 51.0 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 S190828l, but the CAL FOV does not have any overlap with the high probability localization region. The CAL FOV was centered at RA = 106.9 deg, DEC = 51.0 deg at T0. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25538 SUBJECT: LIGO/Virgo S190828l: No counterpart candidates in Fermi-LAT observations DATE: 19/08/29 04:35:52 GMT FROM: Magnus Axelsson at Stockholm U. F. Piron (CNRS/IN2P3/LUPM), N. Omodei (Stanford Univ.), F. Longo (Univ. and INFN Trieste), M. Arimoto (Kanazawa Univ.), D. Kocevski (NASA/MSFC), M. Axelsson (KTH and Stockholm Univ.) and E. Bissaldi (Politecnico and INFN Bari) report on behalf of the Fermi-LAT Collaboration: We have searched data collected by the Fermi Large Area Telescope (LAT) on Aug 28, 2019, for possible high-energy (E > 100 MeV) gamma-ray emission in spatial/temporal coincidence with the LIGO/Virgo trigger S190828l (GCN 25503). 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 22% of the LIGO probability region at the time of the trigger (T0 = 2019-08-28 06:55:09.887 UTC), and reached 100% cumulative coverage after 5.1 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 1.2E-10 and 2.7E-08 [erg/cm^2/s]. The Fermi-LAT point of contact for this event is Frederic Piron (piron@in2p3.fr). 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: 25547 SUBJECT: LIGO/Virgo S190828l: Upper limits from Insight-HXMT/HE observations DATE: 19/08/29 14:01:54 GMT FROM: Qi Luo at IHEP J. M. Yao, Y. G. Zheng, C. Cai, Q. Luo, S. Xiao, Q. B. Yi, Y. Huang, C. K. Li, G. Li, X. B. Li, J. Y. Liao, S. L. Xiong, C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, A. M. Zhang, Y. F. Zhang, X. F. Lu, C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, M. Wu, Y. P. Xu, S. N. Zhang (IHEP), report on behalf of the Insight-HXMT team: Insight-HXMT was taking data normally around the reported LIGO/Virgo S190828l event (GCN #25503), trigger time 2019-08-28T06:55:09.887 UTC. At T0, about 77% of the LIGO localization region was covered by the Insight-HXMT without occultationby the Earth. Within T0 +/- 100 s, no significant excess events (SNR > 3 sigma) are found in a search of the Insight-HXMT/HE raw light curves. Assuming the GW counterpart GRB with three typical GRB Band spectral models, two typical duration timescales (1 s, 10 s) from the center of the LIGO-Virgo location probability map (RA=145 deg, DEC=-50 deg), the 5-sigma upper-limits fluence (0.2 - 5 MeV, incident energy) are reported below: Band model 1 (alpha=-1.9, beta=-3.7, Ep=70 keV): 1 s: 2.5e-07 erg cm^-2 10 s: 1.1e-06 erg cm^-2 Band model 2 (alpha=-1.0, beta=-2.3, Ep=230 keV): 1 s: 4.0e-07 erg cm^-2 10 s: 1.8e-06 erg cm^-2 Band model 3 (alpha=-0.0, beta=-1.5, Ep=1000 keV): 1 s: 8.8e-07 erg cm^-2 10 s: 2.8e-06 erg cm^-2 All measurements above are made with the CsI detectors operating in the regular mode with the energy range of about 80-800 keV (deposited energy). Only gamma-rays with energy greater than about 200 keV can penetrate the spacecraft and leave signals in the CsI detectors installed inside of the spacecraft. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25559 SUBJECT: LIGO/Virgo S190828l: No counterpart candidates in KAIT observations DATE: 19/08/29 22:43:47 GMT FROM: Weikang Zheng at UC Berkeley Shaunak Modak, Sergiy Vasylyev, Thomas de Jaeger, Keto D. Zhang, WeiKang Zheng, Andrew Hoffman, Benjamin E. Stahl, Yukei Murakami, 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-wave event S190828l (GCN 25503) 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 59 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 11:44:07, Aug. 29th UT, about 28.8 hours after the trigger, and the last image at 12:57:58 UT. Our typical limiting mag is 18.5. No viable counterparts were identified and the analysis is ongoing. A full list of galaxies observed by KAIT is given below. GladeID UT(Aug29) RA_J2000 Dec_J2000 ----------------------------------------------- G0595607 11:44:07 03:00:30.444 +49:21:13.3848 G0768405 11:45:18 03:03:32.1653 +49:37:19.7688 G0777619 11:46:32 03:03:40.4251 +51:34:31.8144 G0672859 11:47:43 03:05:05.8877 +50:19:24.096 G0738775 11:48:59 03:06:24.3511 +52:34:54.9264 G0599454 11:50:08 03:10:38.0302 +48:52:10.7328 G0559089 11:51:20 03:27:21.6842 +49:59:01.0032 G0695101 11:52:31 03:37:07.4249 +49:03:08.7444 G0747552 11:53:52 05:11:53.8622 +45:37:14.2356 G0336853 11:55:02 05:13:42.0134 +46:00:58.4064 G0526083 11:56:11 05:16:39.1992 +45:34:27.9696 G1097965 11:57:20 05:17:19.7606 +42:05:05.9568 G0161517 11:58:30 05:17:54.7723 +42:24:03.852 G0626286 11:59:39 05:20:14.154 +43:18:21.4056 G1302293 12:00:48 05:22:14.6686 +41:28:19.902 G0736602 12:01:58 05:24:13.1177 +42:20:18.1356 G0886051 12:03:08 05:25:17.7338 +45:24:10.6488 G1147141 12:04:17 05:25:40.6294 +41:41:53.0124 G1243574 12:05:27 05:25:51.5258 +43:10:11.5536 G1231909 12:06:36 05:26:01.8293 +43:22:56.6292 G1200246 12:07:51 05:26:30.4121 +40:26:56.0076 G0606566 12:09:03 05:27:25.0322 +45:50:49.0344 G0186139 12:10:13 05:27:27.2882 +41:59:04.848 G1414478 12:11:22 05:27:33.9991 +46:11:58.0128 G0926148 12:12:32 05:27:37.8094 +44:08:45.9852 G0934140 12:13:43 05:27:40.9222 +46:09:53.9604 G0284079 12:14:52 05:28:03.9442 +43:09:14.1516 G0386281 12:16:02 05:28:04.477 +43:39:18.162 G1287779 12:17:13 05:28:15.5364 +43:04:08.1264 G1402290 12:18:22 05:29:42.7094 +45:30:00.8928 G0344496 12:25:25 05:29:45.3058 +43:32:20.7348 G0601049 12:26:34 05:29:55.4719 +44:34:38.8056 G0069319 12:27:48 05:30:02.8692 +44:11:51.8172 G0957486 12:28:57 05:30:03.521 +44:38:15.828 G0917178 12:30:13 05:30:04.8065 +41:54:08.2584 G1464030 12:31:22 05:30:04.931 +44:44:55.824 G1121082 12:32:31 05:30:43.9013 +42:25:50.6928 G0841668 12:33:41 05:30:49.9438 +41:12:59.1228 G1331307 12:34:50 05:30:56.1384 +42:40:15.6612 G1190621 12:35:59 05:31:05.7972 +40:40:39.4608 G1122787 12:37:09 05:31:17.3767 +41:54:59.4972 G0412661 12:38:18 05:31:24.0014 +45:52:02.6292 G1138379 12:39:27 05:31:38.6134 +41:45:04.8492 G1027891 12:40:37 05:31:38.9887 +42:30:19.5696 G1216616 12:41:46 05:31:42.2717 +40:59:51.8856 G1385195 12:42:53 05:31:59.0496 +40:46:44.9472 G1101923 12:44:03 05:32:01.8403 +41:39:29.9304 G1125001 12:45:12 05:32:05.5903 +41:40:03.918 G0747978 12:46:20 05:32:17.9518 +42:30:28.2348 G1017116 12:47:30 05:32:37.8588 +45:00:12.114 G1146557 12:48:39 05:33:00.1997 +41:40:23.5164 G0957979 12:49:48 05:33:11.9054 +44:45:11.3292 G1284321 12:50:58 05:33:34.1162 +47:04:33.3408 G0965263 12:52:07 05:33:37.11 +44:33:03.3192 G1417780 12:53:14 05:34:17.5286 +44:35:02.3028 G1471417 12:54:28 05:34:19.9183 +41:45:17.6184 G1176015 12:55:39 05:34:25.2338 +46:23:48.894 G1370730 12:56:48 05:34:56.1785 +44:41:19.86 G1422126 12:57:58 05:35:16.5382 +44:26:24.09 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25593 SUBJECT: LIGO/Virgo S190828l: No significant candidates in TAROT-GRANDMA observations DATE: 19/08/31 21:07:20 GMT FROM: Nelson Christensen at Obs.de la Cote dAzur,Nice S. Antier (APC), C. Lachaud (APC), N. Christensen (Artemis), B. Gendre (OzGrav-UWA), N. Ismayilov (SHAO), M. Boer (Artemis), L. Eymar (Artemis), A. Klotz (IRAP), K. Noysena (Artemis, IRAP), S. Basa (LAM), D. Corre (LAL), M. Coughlin (Caltech), D. Coward (OzGrav-UWA), J.G. Ducoin (LAL), P. Hello (LAL), N. Leroy (LAL), D. Turpin (NAOC), X. Wang (THU) report on behalf of the TAROT network and GRANDMA collaborations. We performed tiled observations of the LIGO/Virgo event S190828l with the TAROT-Chili (TCH), TAROT-Calern (TCA) and TAROT-Reunion (TRE) telescopes operating in the visible located respectively at La Silla ESO Observatory (LaS/ESO), Calern site at the Cote d'Azur Observatory and Les Makes astronomical Observatory. The observation started for TCH on 08/28/19 08:08:26 UTC which corresponds to approximately 74 minutes after the GW trigger time. We performed the following tiled observations : +-------+------------+------------+---------+---------+---------+ | Tele | TStart | TEnd | RA | DEC | Proba | | scope | [UTC] | [UTC] | [deg] | [deg] | [%] | |-------+------------+------------+---------+---------+---------| | TCH | 2019-08-28 | 2019-08-30 | 155.236 | -61.777 | 0.5 | | | 08:08:26 | 09:29:11 | | | | | TCH | 2019-08-28 | 2019-08-29 | 157.656 | -63.595 | 0.5 | | | 08:15:15 | 23:35:28 | | | | | TCH | 2019-08-28 | 2019-08-30 | 149.185 | -58.141 | 0.5 | | | 08:22:03 | 09:41:21 | | | | | TCH | 2019-08-28 | 2019-08-30 | 159.192 | -61.777 | 0.5 | | | 08:28:51 | 09:48:09 | | | | | TCH | 2019-08-28 | 2019-08-30 | 160.538 | -59.959 | 0.3 | | | 09:06:48 | 00:27:25 | | | | | TCH | 2019-08-28 | 2019-08-29 | 163.148 | -61.777 | 0.3 | | | 08:51:18 | 09:33:23 | | | | | TCH | 2019-08-28 | 2019-08-30 | 153.421 | -63.595 | 0.3 | | | 08:58:06 | 00:39:41 | | | | | TCH | 2019-08-28 | 2019-08-28 | 152.715 | -58.141 | 0.8 | | | 09:29:56 | 09:58:42 | | | | | TCH | 2019-08-28 | 2019-08-30 | 153.115 | -59.959 | 0.7 | | | 09:36:44 | 09:08:47 | | | | | TCH | 2019-08-28 | 2019-08-30 | 156.244 | -58.141 | 0.6 | | | 10:14:23 | 09:22:23 | | | | | TCH | 2019-08-28 | 2019-08-30 | 151.28 | -61.777 | 0.3 | | | 08:37:52 | 00:20:37 | | | | | TCH | 2019-08-28 | 2019-08-30 | 166.126 | -63.595 | 0.2 | | | 23:39:52 | 00:46:29 | | | | | TCH | 2019-08-28 | 2019-08-30 | 167.45 | -65.414 | 0.2 | | | 23:46:40 | 00:53:17 | | | | | TCH | 2019-08-29 | 2019-08-30 | 156.826 | -59.959 | 0.6 | | | 00:39:07 | 09:15:35 | | | | | TCH | 2019-08-29 | 2019-08-30 | 162.95 | -65.414 | 0.4 | | | 01:37:16 | 00:13:48 | | | | | TCH | 2019-08-29 | 2019-08-30 | 153.95 | -65.414 | 0.2 | | | 00:01:13 | 08:35:31 | | | | | TCH | 2019-08-29 | 2019-08-30 | 158.45 | -65.414 | 0.4 | | | 01:24:45 | 10:01:45 | | | | | TCH | 2019-08-29 | 2019-08-29 | 149.404 | -59.959 | 0.4 | | | 09:00:58 | 09:07:28 | | | | | TCH | 2019-08-29 | 2019-08-30 | 161.49 | -67.232 | 0.2 | | | 09:52:35 | 01:00:05 | | | | | TCH | 2019-08-29 | 2019-08-30 | 161.891 | -63.595 | 0.5 | | | 01:17:57 | 09:54:57 | | | | |-------+------------+------------+---------+---------+---------| | TCA | 2019-08-28 | 2019-08-28 | -0.95 | 40.372 | 0.3 | | | 19:25:55 | 19:32:26 | | | | | TCA | 2019-08-28 | 2019-08-29 | 356.118 | 39.897 | 0.2 | | | 19:32:44 | 00:38:48 | | | | | TCA | 2019-08-28 | 2019-08-30 | 20.793 | 50.125 | 0.2 | | | 19:39:35 | 01:45:21 | | | | | TCA | 2019-08-28 | 2019-08-28 | 358.467 | 42.228 | 0.2 | | | 20:11:14 | 20:17:43 | | | | | TCA | 2019-08-28 | 2019-08-28 | 5.915 | 42.703 | 0.1 | | | 20:18:03 | 20:24:35 | | | | | TCA | 2019-08-28 | 2019-08-30 | 21.606 | 51.981 | 0.1 | | | 20:24:55 | 02:30:44 | | | | | TCA | 2019-08-28 | 2019-08-29 | 6.056 | 44.558 | 0.1 | | | 21:16:04 | 22:22:35 | | | | | TCA | 2019-08-28 | 2019-08-29 | 22.768 | 48.27 | 0.1 | | | 21:22:55 | 22:29:26 | | | | | TCA | 2019-08-28 | 2019-08-29 | 3.503 | 44.558 | 0.1 | | | 21:29:46 | 22:36:15 | | | | | TCA | 2019-08-28 | 2019-08-30 | 3.433 | 42.703 | 0.2 | | | 22:21:49 | 01:59:03 | | | | | TCA | 2019-08-28 | 2019-08-28 | 0.95 | 42.703 | 0.2 | | | 22:28:37 | 22:35:08 | | | | | TCA | 2019-08-28 | 2019-08-28 | 4.357 | 40.847 | 0.2 | | | 22:35:30 | 22:42:00 | | | | | TCA | 2019-08-28 | 2019-08-28 | 18.655 | 51.981 | 0.1 | | | 23:26:38 | 23:33:08 | | | | | TCA | 2019-08-28 | 2019-08-29 | 355.985 | 41.753 | 0.1 | | | 23:33:27 | 19:39:36 | | | | | TCA | 2019-08-28 | 2019-08-29 | 23.627 | 50.125 | 0.1 | | | 23:40:17 | 19:44:12 | | | | | TCA | 2019-08-29 | 2019-08-30 | 1.941 | 40.847 | 0.2 | | | 00:46:00 | 01:52:12 | | | | | TCA | 2019-08-29 | 2019-08-30 | 20.041 | 48.27 | 0.1 | | | 01:31:03 | 02:37:35 | | | | | TCA | 2019-08-29 | 2019-08-29 | 17.958 | 50.125 | 0.1 | | | 01:37:52 | 21:42:04 | | | | | TCA | 2019-08-29 | 2019-08-29 | 353.702 | 39.897 | 0.1 | | | 21:44:38 | 21:51:09 | | | | |-------+------------+------------+---------+---------+---------| | TRE | 2019-08-28 | 2019-08-28 | 331.034 | 8.182 | 0.4 | | | 21:08:23 | 21:14:51 | | | | | TRE | 2019-08-28 | 2019-08-28 | 338.571 | 16.364 | 0.4 | | | 21:21:39 | 21:28:07 | | | | | TRE | 2019-08-28 | 2019-08-29 | 354.857 | 36.818 | 1.2 | | | 22:02:37 | 20:39:07 | | | | | TRE | 2019-08-28 | 2019-08-29 | 330 | 16.364 | 0.3 | | | 23:57:44 | 00:04:12 | | | | | TRE | 2019-08-29 | 2019-08-29 | 350.27 | 32.727 | 1.4 | | | 00:26:17 | 00:32:45 | | | | | TRE | 2019-08-29 | 2019-08-29 | 342 | 24.545 | 1.1 | | | 00:39:00 | 00:45:28 | | | | | TRE | 2019-08-29 | 2019-08-29 | 330.698 | 12.273 | 0.7 | | | 16:23:40 | 16:30:08 | | | | | TRE | 2019-08-29 | 2019-08-29 | 333.659 | 20.455 | 0.5 | | | 16:41:25 | 16:43:25 | | | | | TRE | 2019-08-29 | 2019-08-29 | 345.974 | 28.636 | 1.1 | | | 20:45:52 | 20:52:26 | | | | +-------+------------+------------+---------+---------+---------+ TStart and TEnd refer respectively to the time of the first and last exposure for a given tile. Observations are not necessarily continuous in this interval. The Probability refers to the 2D spatial probability of the GW skymap enclosed in a given tile. Each tile is 1.9x1.9 degrees for TCA and TCH and 4.2x4.2 degrees for TRE. The coordinating observations cover about 18% of the cumulative probability of the bayestar skymap available on Aug 28, 2019 07:17:33 UTC. The typical limiting magnitude is 18.0 for a 60.0 s exposure for TCH and TCA and 17.0 for a 60.0 s exposure for TRE. The coverage map is available at: https://grandma-owncloud.lal.in2p3.fr/index.php/s/JF7J7CIdlrc7qs1 No significant transient candidates were found during our low latency analysis. GRANDMA (Global Rapid Advanced Network Devoted to the Multi-messenger Addicts) is a network of robotic telescopes connected all over the world with both photometry and spectrometry capabilities for Time-domain Astronomy (https://grandma.lal.in2p3.fr/). Details on the TAROT telescope are available on the GRANDMA web pages or on http://tarot.obs-hp.fr/. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25629 SUBJECT: LIGO/Virgo S190828l: no counterpart candidate in the SVOM/GWAC observations DATE: 19/09/03 12:42:53 GMT FROM: Nicolas Dagoneau at CEA/IRFU/DAp/SVOM J. Y. Wei (NAOC), X. H. Han (NAOC), N. Dagoneau (CEA/AIM), J. Wang (GXU), N. Leroy (CNRS/LAL) on behalf of the SVOM Multi Messenger Astronomy and GWAC teams: http://www.svom.fr/en/svom-mma-and-gwac-team We observed 16 sky regions (total: 2400 square degrees with overlaps) to cover the skymap of the advanced LIGO/Virgo trigger S190828l, with SVOM/GWAC, at Xinglong Observatory equipped with a set of two types of wide angle cameras: FFOV cameras (FOV~900 square degrees/camera, aperture = 3.5 cm) and JFOV cameras (FOV~150 square degrees/camera, aperture = 18 cm). SVOM/GWAC currently comprises 4 FFOV cameras and 16 JFOV cameras, working with unfiltered band. The observations are operated in time-series mode, taking one exposure every 25 seconds (20s exposure + 5s readout). We estimate a 9.5% prior probability that the 16 observed and processed regions contain the true location of the source. The images were taken between ~5 hours and ~12 hours after the event trigger time. The coordinates of the 16 sky regions and observation times are listed below: No. Ra  Dec start-obs(UTC)  end-obs(UTC)    Camera_TYPE 1 00:22:12.55 35:47:18.96 2019-08-28 14:58:26 2019-08-28 15:16:39 JFOV 2 00:16:40.40 47:47:40.20 2019-08-28 14:59:15 2019-08-28 15:17:03 JFOV 3 00:05:09.89 34:55:44.40 2019-08-28 15:00:32 2019-08-28 15:17:08 JFOV 4 01:11:41.69 47:17:32.64 2019-08-28 15:07:01 2019-08-28 15:17:08 JFOV 5 01:43:32.26 64:07:03.00 2019-08-28 13:53:25 2019-08-28 16:51:08 JFOV 6 00:07:40.03 51:45:14.40 2019-08-28 16:41:24 2019-08-28 16:44:15 JFOV 7 00:13:04.03 64:02:39.84 2019-08-28 17:05:25 2019-08-28 17:22:48 JFOV 8 02:38:20.69 47:18:19.08 2019-08-28 17:04:13 2019-08-28 17:22:03 JFOV 9 01:31:55.32 34:55:32.16 2019-08-28 17:09:05 2019-08-28 17:22:03 JFOV 10 21:55:06.96 10:04:51.24 2019-08-28 16:04:03 2019-08-28 16:20:14 JFOV 11 21:55:29.52 -1:58:15.89 2019-08-28 16:00:25 2019-08-28 16:20:14 JFOV 12 21:59:13.44 48:02:44.52 2019-08-28 13:40:52 2019-08-28 14:06:20 JFOV 13 22:05:10.08 34:10:09.48 2019-08-28 12:08:19 2019-08-28 19:00:58 JFOV 14 23:07:07.68 09:08:42.00 2019-08-28 17:49:12 2019-08-28 17:54:27 JFOV 15 23:44:10.08 13:41:13.56 2019-08-28 18:09:03 2019-08-28 18:26:03 JFOV 16 00:58:52.99 30:19:11.28 2019-08-28 17:25:15 2019-08-28 17:53:12 JFOV The sky coverage map is available at: http://cmm.svom.cn/gwpub/O3/S190828l/S190828l.png (user:svomo3 pwd:gwo3) The weather conditions were hazy during the observations. A 3 sigma limiting magnitude of about 16.3 mag in R band was obtained in the single frames. No credible new source is detected by our online pipeline during follow-up observations. A more detailed image analysis including co-addition is ongoing with our offline pipeline to search for transient candidates. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25782 SUBJECT: LIGO/Virgo S190828l: Updated Sky Localization DATE: 19/09/19 14:56:25 GMT FROM: Olivier Minazzoli at LIGO Virgo Collaboration The LIGO Scientific Collaboration and the Virgo Collaboration report: We have conducted further analysis of the data from LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1) and Virgo Observatory (V1) around the time of the compact binary merger (CBC) candidate S190828l (GCN Circular 25503). Parameter estimation has been performed using LALInference [1] and a new sky map, LALInference.v2.fits.gz, distributed via GCN Notice, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S190828l The preferred sky map at this time is LALInference.v2.fits.gz. The 90% credible region is 359 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1528 +/- 387 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)