//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25497 SUBJECT: LIGO/Virgo S190828j: Identification of a GW compact binary merger candidate DATE: 19/08/28 07:17:40 GMT FROM: Olivier Minazzoli at LIGO Virgo Collaboration The LIGO Scientific Collaboration and the Virgo Collaboration report: We identified the compact binary merger candidate S190828j during real-time processing of data from LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) at 2019-08-28 06:34:05.756 UTC (GPS time: 1251009263.756). The candidate was found by the GstLAL [1], CWB [2], PyCBC Live [3], MBTAOnline [4], and SPIIR [5] analysis pipelines. S190828j is an event of interest because its false alarm rate, as estimated by the online analysis, is 8.5e-22 Hz, or about one in 1e14 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S190828j 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 [6], distributed via GCN notice about 16 minutes after the candidate For the bayestar.fits.gz sky map, the 90% credible region is 603 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 2276 +/- 538 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] 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: 25498 SUBJECT: LIGO/Virgo S190828j: No counterpart candidates in AGILE-MCAL observations DATE: 19/08/28 07:49:25 GMT FROM: Francesco Longo at U of Trieste,INFN Trieste F. Longo (Univ. Trieste, and INFN Trieste), C. Pittori, F. Verrecchia (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 S190828j at T0 = 2019-08-28 06:34:05.756 (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 40% of the S190828j 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 S190828j localization region, from a minimum of 1.55E-06 erg cm^-2 to a maximum of 7.31E-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: 25499 SUBJECT: LIGO/Virgo S190828j: No counterpart candidates in HAWC observations DATE: 19/08/28 07:56:52 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 S190828j (GCN #25497). At the time of the trigger the HAWC local zenith was oriented towards (RA, Dec) = (337.2 deg, 18.9 deg). 40% 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 15.3 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 1.7e-06 erg/cm^2 to 1.1e-04 erg/cm^2 (9.1e-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: 25500 SUBJECT: LIGO/Virgo S190828j: No counterpart candidates in INTEGRAL SPI-ACS prompt observation DATE: 19/08/28 08:37:47 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 S190828j (GCN 25497). At the time of the event (2019-08-28 06:34:05 UTC, hereafter T0), INTEGRAL was operating in nominal mode. The peak of the event localization probability was at an angle of 83 deg with respect to the spacecraft pointing axis. This orientation implies strongly suppressed (11% of optimal) response of ISGRI, strongly suppressed (31% of optimal) response of IBIS/Veto, and near-optimal (80% of optimal) response of SPI-ACS. The background within +/-300 seconds around the event was very stable (excess variance 1.2). 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 2e-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 ~1.7e-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 2276.0 Mpc this corresponds to the limit on the total isotropic equivalent energy in 1 s of 1.2e+50 erg for the short GRB spectrum and for a long GRB spectrum isotropic equivalent luminosity in 1 s (8 s) of 1.1e+50 erg/s (3.5e+49 erg/s) We report for completeness and in order of FAP, all excesses identified in the search region. We find 9 background excesses: scale | T | S/N | luminosity ( x 1e+50 erg/s) | FAP 5.2 | -276 | 3.9 | 9.22 +/- 3.03 +/- 5.34 | 0.2 0.55 | -20.1 | 3.6 | 27.9 +/- 9.38 +/- 16.2 | 0.223 0.1 | -1.25 | 3.1 | 5.75 +/- 2.22 +/- 3.33 | 0.249 0.2 | 10.7 | 3.5 | 4.58 +/- 1.56 +/- 2.65 | 0.393 1.6 | 37.3 | 3.1 | 13.9 +/- 5.48 +/- 8.05 | 0.46 1.4 | -135 | 3.6 | 17.3 +/- 5.86 +/- 10 | 0.547 0.05 | -7.63 | 3.6 | 9.67 +/- 3.17 +/- 5.6 | 0.564 0.55 | 63.4 | 3.5 | 27.3 +/- 9.38 +/- 15.8 | 0.807 0.95 | -60.6 | 3.2 | 19.3 +/- 7.12 +/- 11.2 | 0.83 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: 25504 SUBJECT: SUBJECT: LIGO/Virgo S190828j: Updated Sky Localization DATE: 19/08/28 08:56:19 GMT FROM: Olivier Minazzoli at LIGO Virgo Collaboration The LIGO Scientific Collaboration and Virgo Collaboration report: We have updated the skymap for the compact binary merger candidate S190828j (GCN 25497). The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S190828j/ bayestar.fits.gz is the preferred sky map at this time and can be retrieved from the GraceDB event page: * bayestar.fits.gz, an updated localization generated by BAYESTAR [1], distributed via GCN update notice about 1.5 hours after the candidate The 90% credible region is 587 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1803 +/- 423 Mpc (a posteriori mean +/- standard deviation). Note that S190828j (GCN 25497) and S190828l (GCN 25503) are distinct events that occurred 21 minutes apart. For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo Public Alerts User Guide < https://emfollow.docs.ligo.org/userguide/>. [1] Singer & Price PRD 93, 024013 (2016) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25506 SUBJECT: LIGO/Virgo S190828j: Upper limits from AGILE-GRID observations DATE: 19/08/28 09:07:17 GMT FROM: Francesco Verrecchia at ASDC F. Longo (Univ. Trieste, and INFN Trieste), C. Pittori, F. Verrecchia (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 S190828j at T0 = 2019-08-28 06:34:05.756 UT a preliminary analysis of the AGILE exposure at T0 shows that the Gamma-Ray Imaging Detector (GRID) exposure covered more than 15% of the 90% c.l. localization region (LR) (32% of 90% c.l. localization region (LR) is occulted by Earth). We performed an analysis of the GRID data in the energy range 50 MeV - 10 GeV on T0, where good exposure of the S190828j 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 7.9e-07 to 9.74e-06 erg cm^-2 s^-1, with exposure of about 36% of the LR over the time interval ( T0 -2s ; T0 + 2s ); from 6.5e-07 to 6.1e-06 erg cm^-2 s^-1, with exposure of about 34% of the LR over the time interval ( T0s ; T0 + 5s ); from 3.39e-07 to 6e-06 erg cm^-2 s^-1, with exposure of about 34% of the LR over the time interval ( T0s ; T0 + 10s ); from 1.3e-07 to 5.91e-06 erg cm^-2 s^-1, with exposure of about 36% of the LR over the time interval ( T0s ; T0 + 100s ); A map in Galactic coordinates showing the AGILE FoV at T0 is available at the site: https://tools.ssdc.asi.it/ImgView/Agile/aitoff_MULTImap2019-08-28-4s_mod19 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: 25508 SUBJECT: LIGO/Virgo S190828j : no neutrino counterpart candidate in ANTARES search DATE: 19/08/28 09:28:43 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 S190828j event using the 90% contour of the Initial bayestar probability map provided by the GW interferometers (GCN#25497 ). 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/S190828j_Initial.png . Considering the location probability provided by the LIGO/Virgo collaborations, there is a 53.1% 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 2019-08-28 06:34:05 and in the 90% contour of the S190828j event. The expected number of atmospheric background events in the region visible by ANTARES is 1.67e-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 1.20e-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: 25509 SUBJECT: LIGO/Virgo S190828j: Coverage and upper limits from MAXI/GSC observations DATE: 19/08/28 09:56:47 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 S190828j at 2019-08-28 06:34:05.756 UTC (GCN 25497). At the trigger time of S190828j, 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 94% of the 90% credible region of the bayestar skymap from 06:34:05 to 08:06:01 UTC (T0+0 to T0+5516 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: 25513 SUBJECT: LIGO/Virgo S190828j: Upper limits from IceCube neutrino searches DATE: 19/08/28 10:57:01 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 S190828j in a time range of 1000 seconds [3] centered on the alert event time (2019-08-28 06:25:45.756 UTC to 2019-08-28 06:42:25.756 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 S190828j calculated from the map circulated in the 3-Update 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 S190828j ranges from 0.034 to 0.841 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: 25522 SUBJECT: LIGO/Virgo S190828j: Upper limits from Fermi-GBM Observations DATE: 19/08/28 16:14:43 GMT FROM: Peter Veres at UAH P. Veres (UAH) reports on behalf of the Fermi-GBM Team and the GBM-LIGO/Virgo group: For S190828j and using the updated bayestar skymap (GCN 25504), Fermi-GBM was observing 83% 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 S190828j (GCN 25497). 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: 5.5e-07 7.5e-07 1.7e-06 1.024 s: 1.8e-07 2.8e-07 6.8e-07 8.192 s: 7.1e-08 1.3e-07 2.5e-07 Assuming the median luminosity distance of 1800 Mpc (z=0.34) 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 4.1 16 1.024 s: 1.1 1.5 6.2 8.192 s: 0.44 0.71 2.3 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25530 SUBJECT: LIGO/Virgo S190828j: No counterpart candidates in Fermi-LAT observations DATE: 19/08/28 22:43:12 GMT FROM: Frederic Piron at CNRS/IN2P3/LUPM 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 S190828j (GCN 25497). 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 a null instantaneous coverage of the LIGO probability region at the time of the trigger (T0 = 2019-08-28 06:34:05.756UTC), and reached ~52% cumulative coverage after 10 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 4.3e-10 and 8.5e-8 [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: 25531 SUBJECT: LIGO/Virgo S190828j: No counterpart candidates in KAIT observations DATE: 19/08/28 22:45:33 GMT FROM: Weikang Zheng at UC Berkeley Keto D. Zhang, Sergiy Vasylyev, Thomas de Jaeger, 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-wavei event S190828j (GCN 25497) 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 84 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 07:10:51, Aug. 28th UT, about 37 minutes after the trigger, and the last image at 12:59:08 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(Aug28) RA_J2000 Dec_J2000 ----------------------------------------------- G1411338 07:10:51 00:00:42.1697 +62:28:27.9912 G0108194 07:12:09 00:02:34.6301 +59:10:45.9012 G1437181 07:13:18 00:04:43.1198 +60:54:53.7408 G1376191 07:14:27 00:04:50.1787 +61:08:02.7816 G0915623 07:15:37 00:06:55.8847 +60:56:16.6632 G0040914 07:16:46 00:09:18.455 +60:52:27.1164 G0023757 07:17:54 00:10:06.7973 +61:36:45.864 G0960102 07:19:03 00:10:20.1641 +60:46:39.81 G0857314 07:20:12 00:11:03.7274 +59:44:23.334 G0286480 07:21:22 00:12:01.2106 +59:41:10.5108 G1256548 07:22:31 00:13:02.2044 +59:55:55.596 G0382218 07:23:40 00:15:37.1263 +59:11:37.6332 G0178384 07:24:50 00:16:02.4991 +59:29:08.79 G0354798 07:25:59 00:16:41.8795 +61:02:41.0064 G1236761 07:27:08 00:16:55.019 +62:32:58.0488 G1104060 07:28:17 00:17:17.959 +62:50:17.9016 G0197398 07:29:27 00:19:02.5733 +63:03:57.7152 G1108946 07:30:36 00:19:38.0712 +62:25:39.9828 G0410793 07:31:47 00:21:19.2425 +63:18:59.4468 G0412316 07:32:57 00:23:11.5109 +63:14:27.8376 G1335438 07:34:06 00:24:22.8192 +63:29:54.6576 G0040683 07:35:18 00:25:05.8135 +62:09:01.3248 G1311682 07:36:27 00:28:01.1556 +61:13:34.5828 G1353194 07:37:34 00:28:32.2651 +62:25:30.162 G1411338 08:16:50 00:00:42.1697 +62:28:27.9912 G1437181 08:17:59 00:04:43.1198 +60:54:53.7408 G1376191 08:19:09 00:04:50.1787 +61:08:02.7816 G0915623 08:20:18 00:06:55.8847 +60:56:16.6632 G0040914 08:21:27 00:09:18.455 +60:52:27.1164 G0023757 08:22:37 00:10:06.7973 +61:36:45.864 G0960102 08:23:46 00:10:20.1641 +60:46:39.81 G0857314 08:25:08 00:11:03.7274 +59:44:23.334 G0286480 08:26:17 00:12:01.2106 +59:41:10.5108 G1256548 08:27:25 00:13:02.2044 +59:55:55.596 G0382218 08:28:35 00:15:37.1263 +59:11:37.6332 G0178384 08:29:44 00:16:02.4991 +59:29:08.79 G0354798 08:30:53 00:16:41.8795 +61:02:41.0064 G1236761 08:32:02 00:16:55.019 +62:32:58.0488 G1104060 08:33:12 00:17:17.959 +62:50:17.9016 G0197398 08:34:21 00:19:02.5733 +63:03:57.7152 G1108946 08:35:33 00:19:38.0712 +62:25:39.9828 G0410793 08:36:42 00:21:19.2425 +63:18:59.4468 G0412316 08:37:49 00:23:11.5109 +63:14:27.8376 G1335438 08:38:59 00:24:22.8192 +63:29:54.6576 G0040683 08:40:08 00:25:05.8135 +62:09:01.3248 G1353194 08:41:17 00:28:32.2651 +62:25:30.162 G0341361 08:42:26 00:28:34.0399 +61:37:03.1656 G0040540 08:43:38 00:32:50.7516 +64:01:35.1156 G1125714 08:44:47 00:33:18.3127 +61:27:43.344 G0195596 08:45:56 00:35:06.0497 +62:46:14.376 G0133562 08:47:08 00:35:47.389 +64:04:54.9552 G0083833 08:48:17 00:39:39.6461 +62:56:06.2232 G0304019 08:49:26 00:44:44.6424 +62:03:38.97 G0332087 08:50:48 00:45:19.158 +65:27:13.1436 G1232494 08:52:43 00:46:53.2234 +63:08:07.764 G0058140 08:53:53 00:49:35.4175 +64:51:58.608 G0026909 08:55:02 00:52:34.2317 +63:11:28.7484 G0215715 08:56:11 00:52:46.4971 +65:50:02.7564 G0211497 08:57:21 00:55:03.9209 +62:44:28.3308 G0463440 08:58:30 00:58:21.8878 +63:37:25.1796 G0107445 08:59:39 01:01:53.0525 +63:15:32.0112 G0414645 09:00:49 01:06:47.1456 +64:40:42.9204 G0297094 09:01:58 01:14:20.381 +63:43:33.4128 G0544341 09:03:07 01:15:33.0602 +63:37:00.0624 G0043239 09:04:17 01:18:36.6046 +63:48:39.78 G0858497 09:05:36 02:08:29.8543 +64:31:02.7048 G0461687 12:39:17 22:37:39.4555 +51:03:50.5224 G1468559 12:40:26 22:37:49.2626 +50:50:28.4928 G1369384 12:41:35 22:41:18.6254 +52:11:20.5224 G1286759 12:42:45 22:42:40.2319 +53:50:01.9716 G0329445 12:43:54 22:43:08.5181 +51:34:07.9464 G1187210 12:45:03 22:44:21.6871 +53:37:55.5168 G0518266 12:46:19 23:16:30.0146 +57:53:27.7872 G0464426 12:47:26 23:18:14.2603 +58:32:36.6108 G0417225 12:48:38 23:20:05.3686 +58:21:10.7064 G0894934 12:49:47 23:21:59.502 +57:00:07.4448 G0322333 12:50:56 23:27:15.4762 +58:45:09.7236 G0312471 12:52:08 23:30:53.401 +57:16:46.7184 G1042257 12:53:17 23:32:23.0126 +58:24:54.0576 G1074414 12:54:26 23:33:31.5746 +57:52:19.3836 G0085132 12:55:38 23:35:10.979 +59:34:58.7856 G0843567 12:56:47 23:36:16.4354 +58:41:06.7344 G0307552 12:57:56 23:37:05.4859 +59:24:34.956 G0218409 12:59:08 23:40:07.6903 +59:59:08.9016 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25532 SUBJECT: LIGO/Virgo S190828j: no counterpart candidates in the Swift/BAT Observations DATE: 19/08/28 22:55:21 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), 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 S190828j (LIGO/VIRGO Collaboration GCN Circ. 25497), where T0 is the LVC trigger time (2019-08-28T06:34:05.756 UTC). The center of the BAT FOV at T0 is RA = 214.805 deg, DEC = -26.634 deg, The roll angle is 299.633 deg. The BAT Field of View (>10% partial coding) covers 34.90% of the integrated LVC localization probability, and 34.83% 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 ~ 9.00 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 44.63% 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/S190828j/web/source_public.html //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25536 SUBJECT: LIGO/Virgo S190828j: No transient candidates in CALET observations DATE: 19/08/29 04:10:29 GMT FROM: Yuta Kawakubo at Louisiana State U./CALET S. Torii (Waseda 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 (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 S190828j T0 = 2019-08-28 06:34:05.756 UT (The LIGO Scientific Collaboration and Virgo Collaboration, GCN Circ. 25497). 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 both 42 % (and 42 % credible region of the updated localization map was above the horizon). The HXM and SGM fields of view were centered at RA = 5.4 deg, Dec = 18.4 deg and RA = 13.9 deg, Dec = 12.7 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 S190828j, but the CAL FOV does not have any overlap with the high probability localization region. The CAL FOV was centered at RA= 13.9 deg, DEC= 12.6 deg at T0. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25562 SUBJECT: LIGO/Virgo S190828j: No Counterparts in DDOTI/OAN Optical Observations DATE: 19/08/30 03:17:58 GMT FROM: Emma Margarita Pereyra Talamantes at IA-UNAM Ensenada Margarita Pereyra (UNAM), Simone Dichiara (GSFC/UMD), Alan M. Watson (UNAM), Nat Butler (ASU), Rosa L. Becerra (UNAM), Diego Gonzalez (UNAM), Alexander Kutyrev (GSFC/UMD), William H. Lee (UNAM), Eleonora Troja (GSFC/UMD), Gabriele Minervini (INAF/IAPS-Rome) and Tanner Wolfram (ASU) report: We observed LIGO/Virgo S190828j event (Minazzoli et al., GCN #25497) with the DDOTI/OAN wide-field imager at the Observatorio Astronomico Nacional on Sierra San Pedro Martir (http://ddoti.astroscu.unam.mx) from 2019-08-28 08:00 to 2019-08-28 11:57 UTC (1.4 to 5.4 hours after the event). We observed approximately 231 square degrees of the sky, with four pointings centered on 22:10:13.126 +45:18:17.26, 21:45:30.680 +39:42:01.13, 21:25:37.437 +32:53:21.57 and 21:07:43.518 +24:13:55.90. We obtained about 21, 16, 18 and 86 minutes total exposure on each pointing, respectively. These regions include about 35% of the 2D probability in the current BAYESTAR map. We calibrated our images against the APASS catalog. Our 10-sigma limiting magnitude are typically between w = 19.2 and w = 19.8. Comparing our 10-sigma detections against the USNO-B1 catalog, we detect no uncataloged sources with significant fading. We thank the staff of the Observatorio Astronomico Nacional in San Pedro Martir. -- *Dr. Margarita Pereyra * *FFTF, Schlumberger Foundation Alumnae* ---------------------------------------------------------------------------------------------------------------- *Catedrático Conacyt* *Instituto de Astronomía de la UNAM,* *Km. 107 Carretera Tijua**na-Ensenada, * *Ensenada Baja California, México. C.P. 22860* Oficina: 405 Skype: margarita-pereyra //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25594 SUBJECT: LIGO/Virgo S190828j : No significant candidates in TAROT-GRANDMA observations DATE: 19/08/31 21:23:06 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. Noysen (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 S190828j 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), the Calern site at the Cote d'Azur Observatory and Les Makes astronomical observatory. The observation started for TCH on 08/28/19 07:05:39 UTC which corresponds approximately to 32 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 | 312.95 | 12.768 | 0.1 | | | 07:05:39 | 03:48:14 | | | | | TCH | 2019-08-28 | 2019-08-30 | 309.933 | 9.05 | 0.1 | | | 07:34:47 | 03:55:02 | | | | | TCH | 2019-08-29 | 2019-08-30 | 314.525 | 27.707 | 0.1 | | | 00:24:53 | 01:31:01 | | | | | TCH | 2019-08-29 | 2019-08-30 | 319.388 | 21.777 | <0.1 | | | 03:00:41 | 06:37:09 | | | | | TCH | 2019-08-29 | 2019-08-30 | 314.558 | 13.161 | <0.1 | | | 03:07:29 | 06:43:58 | | | | | TCH | 2019-08-30 | 2019-08-30 | 213.626 | -61.777 | 0.2 | | | 03:34:54 | 03:41:24 | | | | |-------+------------+------------+---------+---------+---------| | TCA | 2019-08-28 | 2019-08-28 | 330.312 | 44.558 | 1.1 | | | 19:04:46 | 19:11:17 | | | | | TCA | 2019-08-28 | 2019-08-29 | 331.832 | 46.414 | 0.9 | | | 19:11:36 | 20:17:45 | | | | | TCA | 2019-08-28 | 2019-08-30 | 328.674 | 42.703 | 0.8 | | | 19:18:25 | 01:24:18 | | | | | TCA | 2019-08-28 | 2019-08-28 | 8.45 | 61.259 | 0.7 | | | 19:50:08 | 19:56:38 | | | | | TCA | 2019-08-28 | 2019-08-29 | 334.479 | 46.414 | 0.7 | | | 19:56:57 | 01:03:10 | | | | | TCA | 2019-08-28 | 2019-08-29 | 343.245 | 51.981 | 0.6 | | | 20:03:48 | 21:09:42 | | | | | TCA | 2019-08-28 | 2019-08-29 | 324.708 | 39.897 | 0.5 | | | 20:54:56 | 19:32:34 | | | | | TCA | 2019-08-28 | 2019-08-29 | 12.818 | 63.115 | 0.5 | | | 21:01:45 | 02:08:44 | | | | | TCA | 2019-08-28 | 2019-08-28 | 342.488 | 53.837 | 0.4 | | | 21:08:35 | 21:15:05 | | | | | TCA | 2019-08-28 | 2019-08-30 | 12.2 | 61.259 | 0.8 | | | 22:00:42 | 01:37:59 | | | | | TCA | 2019-08-28 | 2019-08-29 | 327.125 | 40.372 | 0.8 | | | 22:07:32 | 23:14:25 | | | | | TCA | 2019-08-28 | 2019-08-28 | 331.157 | 42.703 | 0.7 | | | 22:14:21 | 22:20:50 | | | | | TCA | 2019-08-28 | 2019-08-28 | 336.404 | 48.27 | 0.5 | | | 22:59:06 | 23:05:36 | | | | | TCA | 2019-08-28 | 2019-08-29 | 333.677 | 48.27 | 0.5 | | | 23:05:56 | 19:12:05 | | | | | TCA | 2019-08-28 | 2019-08-29 | 329.541 | 40.847 | 0.5 | | | 23:12:46 | 19:18:54 | | | | | TCA | 2019-08-28 | 2019-08-29 | 341.108 | 50.125 | 0.5 | | | 23:19:36 | 19:25:44 | | | | | TCA | 2019-08-29 | 2019-08-30 | 332.865 | 44.558 | 0.8 | | | 00:24:58 | 01:31:08 | | | | | TCA | 2019-08-29 | 2019-08-30 | 345.565 | 53.837 | 0.6 | | | 01:10:19 | 02:16:27 | | | | | TCA | 2019-08-29 | 2019-08-30 | 338.273 | 50.125 | 0.6 | | | 01:17:10 | 02:23:17 | | | | |-------+------------+------------+---------+---------+---------| | TRE | 2019-08-28 | 2019-08-28 | 324 | 36.818 | 3.6 | | | 21:35:08 | 21:41:42 | | | | | TRE | 2019-08-28 | 2019-08-28 | 317.922 | 28.636 | 2.7 | | | 21:48:24 | 21:54:58 | | | | | TRE | 2019-08-29 | 2019-08-29 | 312.857 | 16.364 | 1.3 | | | 15:43:28 | 15:49:56 | | | | | TRE | 2019-08-29 | 2019-08-29 | 309.767 | 12.273 | 0.6 | | | 16:15:23 | 16:21:51 | | | | | TRE | 2019-08-29 | 2019-08-29 | 321.081 | 32.727 | 3.3 | | | 20:11:45 | 20:18:19 | | | | | TRE | 2019-08-29 | 2019-08-29 | 315 | 24.545 | 1.8 | | | 20:24:55 | 20:31:29 | | | | | TRE | 2019-08-29 | 2019-08-29 | 325.946 | 32.727 | 0.7 | | | 20:56:14 | 21:02:42 | | | | +-------+------------+------------+---------+---------+---------+ 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 26% of the cumulative probability of the bayestar skymap available on Aug 28, 2019 07:36:47 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/tG92ASJWw5C1tWV 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 telescopes are available on the GRANDMA web pages or on http://tarot.obs-hp.fr/. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25628 SUBJECT: LIGO/Virgo S190828j: no counterpart candidate in the SVOM/GWAC observations DATE: 19/09/03 12:39:53 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 9 sky regions (total: 1350 square degrees with overlaps) to cover the skymap of the advanced LIGO/Virgo trigger S190828j, 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 19.6% prior probability that the 9 observed and processed regions contain the true location of the source. The images were taken between ~5.5 hours and ~13 hours after the event trigger time. The coordinates of the 9 sky regions and observation times are listed below: No. Ra  Dec start-obs(UTC)  end-obs(UTC)    Camera_TYPE 1 01:43:32.26 64:07:03.00 2019-08-28 13:53:25 2019-08-28 16:51:08 JFOV 2 00:07:40.03 51:45:14.40 2019-08-28 16:41:24 2019-08-28 16:44:15 JFOV 3 00:13:04.03 64:02:39.84 2019-08-28 17:05:25 2019-08-28 17:22:48 JFOV 4 21:27:48.00 47:17:53.52 2019-08-28 13:03:27 2019-08-28 13:05:53 JFOV 5 20:43:28.32 -1:13:58.98 2019-08-28 13:20:46 2019-08-28 13:35:19 JFOV 6 21:18:27.60 13:20:15.00 2019-08-28 16:08:33 2019-08-28 16:19:54 JFOV 7 20:50:18.72 63:41:09.96 2019-08-28 13:30:52 2019-08-28 13:35:43 JFOV 8 21:59:13.44 48:02:44.52 2019-08-28 13:40:52 2019-08-28 14:06:20 JFOV 9 22:05:10.08 34:10:09.48 2019-08-28 12:08:19 2019-08-28 19:00:58 JFOV The sky coverage map is available at: http://cmm.svom.cn/gwpub/O3/S190828j/S190828j.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: 25861 SUBJECT: LIGO/Virgo S190828j: Updated Sky Localization DATE: 19/09/29 06:41:51 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 S190828j (GCN Circular 25497). 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/S190828j The preferred sky map at this time is LALInference.fits.gz. The 90% credible region is 228 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1946 +/- 388 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 < https://emfollow.docs.ligo.org/userguide/>. [1] Veitch et al. PRD 91, 042003 (2015) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25905 SUBJECT: LIGO/Virgo S190828j: Updated Sky Localization DATE: 19/10/01 18:48:58 GMT FROM: Geoffrey Mo at LIGO 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 S190924h (GCN Circular 25829). 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/S190924h The preferred sky map at this time is LALInference.fits.gz. The 90% credible region is 303 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 548 +/- 112 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 < https://emfollow.docs.ligo.org/userguide/>. [1] Veitch et al. PRD 91, 042003 (2015)