//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24140 SUBJECT: LIGO-Virgo S190421ar: AGILE MCAL observations DATE: 19/04/22 17:10:21 GMT FROM: Alessandro Ursi at INAF/IAPS A. Ursi, M. Cardillo (INAF/IAPS), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), C. Casentini, G. Piano (INAF/IAPS), F. Lucarelli, C. Pittori, F. Verrecchia (SSDC, and INAF/OAR), A. Bulgarelli, N. Parmiggiani (INAF/OAS-Bologna), M. Pilia (INAF/OA-Cagliari), F. Longo (Univ. Trieste, and INFN Trieste) report on behalf of the AGILE Team: In response to the LIGO-Virgo GW event S190421ar at T0 = 2019-04-21 21:38:56 (UT), a preliminary analysis of the AGILE minicalorimeter (MCAL) data found no event candidates within a time interval covering -/+ 1000 sec from the LIGO-Virgo T0. Two-sigma upper limits (ULs) are obtained for a 1 s integration time at different celestial positions within the accessible S190421ar 90% c.l. localization region, from a minimum of 1.30E-06 erg cm^-2 to a maximum of 3.02E-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: 24141 SUBJECT: LIGO/Virgo S190421ar: Identification of a GW compact binary merger candidate DATE: 19/04/22 17:37:44 GMT FROM: Deep Chatterjee at University of Wisconsin, Milwaukee The LIGO Scientific Collaboration and the Virgo Collaboration report: We identified the compact binary merger candidate S190421ar during real-time processing of data from LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at 2019-04-21 21:38:56.251 UTC (GPS time: 1239917954.251). The candidate was found by the PyCBC Live [1], CWB [2], GstLAL [3], MBTAOnline [4], and spiir [5] analysis pipelines. S190421ar is an event of interest because its false alarm rate, as determined by the online analysis, is 1.5e-08 Hz, or about one in 2 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S190421ar The classification of the GW signal, in order of descending probability, is Terrestrial (96%), BBH (4%), BNS (<1%), NSBH (<1%), or MassGap (<1%). We think that BBH probability may be underestimated and the Terrestrial probability may be overestimated; we are reviewing it and will provide an update when available. 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 skymap 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 18 hours after the candidate For the bayestar.fits.gz skymap, the 90% credible region is 1917 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 2281 +/- 697 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo Public Alerts User Guide .  [1] Nitz et al. PRD 98, 024050 (2018)  [2] Klimenko et al. PRD 93, 042004 (2016)  [3] Messick et al. PRD 95, 042001 (2017)  [4] Adams et al. CQG 33, 175012 (2016)  [5] Hooper et al. PRD 86, 024012 (2012)  [6] Singer & Price PRD 93, 024013 (2016) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24142 SUBJECT: Subject: LIGO/VIRGO S190421ar: IceCube Neutrino Search DATE: 19/04/22 17:53:48 GMT FROM: Erik Blaufuss at U. Maryland/IceCube The IceCube Collaboration (http://icecube.wisc.edu/) reports: IceCube has performed a search for track-like muon neutrino events consistent with the sky localization of S190421ar in a time range of 1000 seconds centered on the alert event time (2019-04-21 21:30:36.251 UTC to 2019-04-21 21:47:16.251 UTC) during which IceCube was collecting good quality data. No track-like events are found in spatial coincidence with the 90% spatial containment of S190421ar calculated from the map circulated in the preliminary notice. IceCube's sensitivity to point sources within the location spanned by the 90% spatial containment of S190421ar ranges from 0.029 to 1.150 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 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24143 SUBJECT: AT LIGO-Virgo S190421ar: AGILE GRID observations DATE: 19/04/22 18:30:44 GMT FROM: Martina Cardillo at INAF-IAPS M. Cardillo (INAF/IAPS), F. Verrecchia (SSDC, and INAF/OAR), A. Ursi (INAF/IAPS), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), C. Casentini, G. Piano (INAF/IAPS), F. Lucarelli, C. Pittori (SSDC, and INAF/OAR), A. Bulgarelli, N. Parmiggiani (INAF/OAS-Bologna), M. Pilia (INAF/OA-Cagliari), F. Longo (Univ. Trieste, and INFN Trieste), report on behalf of the AGILE Team: In response to the LIGO-Virgo GW event S190421ar T0 = 2019-04-21 21:38:56 (UTC; GCN #24141), analysis of AGILE data shows that the satellite at T0 was in the South Atlantic Anomaly (SAA). Scientific telemetry was inhibited during the time interval (T0 -600 s; T0 + 400 s). We performed a preliminary analysis of the AGILE Gamma-Ray Imaging Detector (GRID) in the first interval available after the SAA, between T0 +450s and T0+550s. In this time interval, the GRID exposure covered nearly 55% of the LIGO/Virgo localization region (LR), observed at off-axis angles between 15 deg and 60 deg. An analysis of the data in the energy range 50 MeV - 10 GeV in this integration time was performed and preliminary 3-sigma upper limits (UL) values within the accessible LIGO/Virgo LR are: from 4.9e-8 erg cm^-2 s^-1 to 3.0e-7 erg cm^-2 s^-1 for integration time of 100s. These measurements were obtained with AGILE observing a large portion of the sky in spinning mode. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24144 SUBJECT: LIGO/Virgo S190421ar: HAWC follow-up DATE: 19/04/22 18:59:11 GMT FROM: Andrew Smith at UMD/HAWC The HAWC Collaboration performed a follow-up of the gravitational wave trigger S190421ar (GCN #24141). At the time of the trigger the HAWC local zenith was oriented towards (RA, Dec) = (76.8 deg, 19.0 deg), 6% 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 11deg to 31deg for the area searched in this analysis. The 5sigma detection sensitivity to a 1s (100s) burst in the 80-800GeV energy range goes from 1.4e-6 erg/cm^2 to 8.0e-6 erg/cm^2 (7.5e-6 ergs/cm2 to 3.9e-5 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: 24145 SUBJECT: LIGO/Virgo S190421ar Global MASTER-Net observations report DATE: 19/04/22 19:19:02 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, V.Kornilov, D.Kuvshinov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.V.Chazov, D. Vlasenko Lomonosov Moscow State University, Sternberg Astronomical Institute, Moscow State University A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory K. Ivanov, O. Gres, N.M. Budnev, S. Yazev, O. Chuvalaev, V. Poleshchuk Irkutsk State University V. Yurkov, A. Gabovich, Yu. Sergienko Blagoveschensk Educational State University, Blagoveschensk R. Podesta, Carlos Lopez and F. Podesta Observatorio Astronomico Felix Aguilar (OAFA) Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias D. Buckley, S. Potter, A. Kniazev, M. Kotze South African Astronomical Observatory MASTER-Tavrida robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, SAI Crimea astronomical station) started inspect of the LIGO/Virgo S190421ar errorbox 86 sec after trigger time at 2019-04-21 21:40:22 UT, with upper limit up to 19.4 mag. The observations began at zenit distance = 129 deg. The sun altitude is -34.1 deg. MASTER-IAC robotic telescope located in Spain (IAC Teide Observatory) started inspect of the LIGO/Virgo S190421ar errorbox 4702 sec after trigger time at 2019-04-21 22:57:18 UT, with upper limit up to 19.6 mag. The observations began at zenit distance = 152 deg. The sun altitude is -40.0 deg. MASTER-OAFA robotic telescope located in Argentina (OAFA observatory of San Juan National University) started inspect of the LIGO/Virgo S190421ar errorbox 18246 sec after trigger time at 2019-04-22 02:43:02 UT, with upper limit up to 17.3 mag. The observations began at zenit distance = 149 deg. The sun altitude is -58.2 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=10196 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 117 | 2019-04-21 21:40:22 | MASTER-Tavrida | ( 11h 13m 37.02s , + 6d 5m 45.12s) | C | 60 | 18.7 | 117 | 2019-04-21 21:40:22 | MASTER-Tavrida | ( 11h 14m 27.61s , + 6d 9m 35.99s) | C | 60 | 18.8 | 214 | 2019-04-21 21:42:00 | MASTER-Tavrida | ( 11h 20m 16.43s , +10d 5m 24.13s) | C | 60 | 18.7 | 274 | 2019-04-21 21:42:00 | MASTER-Tavrida | ( 11h 20m 16.43s , +10d 5m 24.14s) | C | 180 | 19.4 | Coadd 214 | 2019-04-21 21:42:00 | MASTER-Tavrida | ( 11h 21m 07.29s , +10d 9m 14.90s) | C | 60 | 18.7 | 274 | 2019-04-21 21:42:00 | MASTER-Tavrida | ( 11h 21m 07.29s , +10d 9m 14.89s) | C | 180 | 19.3 | Coadd 308 | 2019-04-21 21:43:33 | MASTER-Tavrida | ( 11h 20m 17.84s , +10d 5m 24.45s) | C | 60 | 18.7 | 308 | 2019-04-21 21:43:33 | MASTER-Tavrida | ( 11h 21m 08.73s , +10d 9m 15.24s) | C | 60 | 18.7 | 399 | 2019-04-21 21:45:05 | MASTER-Tavrida | ( 11h 20m 17.83s , +10d 5m 44.73s) | C | 60 | 18.7 | 399 | 2019-04-21 21:45:05 | MASTER-Tavrida | ( 11h 21m 08.73s , +10d 9m 35.56s) | C | 60 | 18.7 | 497 | 2019-04-21 21:46:42 | MASTER-Tavrida | ( 11h 8m 32.84s , +12d 5m 39.97s) | C | 60 | 18.8 | 557 | 2019-04-21 21:46:42 | MASTER-Tavrida | ( 11h 8m 32.84s , +12d 5m 39.90s) | C | 180 | 19.3 | Coadd 497 | 2019-04-21 21:46:42 | MASTER-Tavrida | ( 11h 9m 24.17s , +12d 9m 30.12s) | C | 60 | 18.6 | 557 | 2019-04-21 21:46:42 | MASTER-Tavrida | ( 11h 9m 24.17s , +12d 9m 30.14s) | C | 180 | 19.3 | Coadd 588 | 2019-04-21 21:48:14 | MASTER-Tavrida | ( 11h 8m 32.84s , +12d 5m 20.35s) | C | 60 | 18.6 | 588 | 2019-04-21 21:48:14 | MASTER-Tavrida | ( 11h 9m 24.18s , +12d 9m 10.34s) | C | 60 | 18.6 | 680 | 2019-04-21 21:49:45 | MASTER-Tavrida | ( 11h 8m 34.26s , +12d 5m 20.69s) | C | 60 | 18.7 | 680 | 2019-04-21 21:49:46 | MASTER-Tavrida | ( 11h 9m 25.62s , +12d 9m 10.54s) | C | 60 | 18.6 | 776 | 2019-04-21 21:51:22 | MASTER-Tavrida | ( 11h 24m 56.10s , +12d 5m 46.57s) | C | 60 | 18.7 | 836 | 2019-04-21 21:51:22 | MASTER-Tavrida | ( 11h 24m 56.09s , +12d 5m 46.58s) | C | 180 | 18.5 | Coadd 776 | 2019-04-21 21:51:22 | MASTER-Tavrida | ( 11h 25m 47.27s , +12d 9m 36.73s) | C | 60 | 18.8 | 836 | 2019-04-21 21:51:22 | MASTER-Tavrida | ( 11h 25m 47.27s , +12d 9m 36.68s) | C | 180 | 18.8 | Coadd 869 | 2019-04-21 21:52:54 | MASTER-Tavrida | ( 11h 24m 54.65s , +12d 5m 47.03s) | C | 60 | 17.6 | 869 | 2019-04-21 21:52:54 | MASTER-Tavrida | ( 11h 25m 45.81s , +12d 9m 37.29s) | C | 60 | 17.7 | 961 | 2019-04-21 21:54:26 | MASTER-Tavrida | ( 11h 24m 54.65s , +12d 5m 27.38s) | C | 60 | 16.8 | 961 | 2019-04-21 21:54:26 | MASTER-Tavrida | ( 11h 25m 45.79s , +12d 9m 17.54s) | C | 60 | 16.8 | 1057 | 2019-04-21 21:56:02 | MASTER-Tavrida | ( 11h 36m 33.18s , +10d 5m 31.75s) | C | 60 | 16.3 | 1117 | 2019-04-21 21:56:02 | MASTER-Tavrida | ( 11h 36m 33.17s , +10d 5m 31.60s) | C | 180 | 15.9 | Coadd 1057 | 2019-04-21 21:56:02 | MASTER-Tavrida | ( 11h 37m 23.86s , +10d 9m 21.82s) | C | 60 | 16.3 | 1117 | 2019-04-21 21:56:02 | MASTER-Tavrida | ( 11h 37m 23.86s , +10d 9m 21.81s) | C | 180 | 16.3 | Coadd 1148 | 2019-04-21 21:57:33 | MASTER-Tavrida | ( 11h 36m 33.22s , +10d 5m 52.15s) | C | 60 | 15.8 | 1148 | 2019-04-21 21:57:33 | MASTER-Tavrida | ( 11h 37m 23.83s , +10d 9m 42.41s) | C | 60 | 15.8 | 1269 | 2019-04-21 21:59:35 | MASTER-Tavrida | ( 11h 36m 31.79s , +10d 5m 52.41s) | C | 60 | 13.6 | 1269 | 2019-04-21 21:59:35 | MASTER-Tavrida | ( 11h 37m 22.32s , +10d 9m 42.74s) | C | 60 | 13.6 | 1389 | 2019-04-21 22:01:35 | MASTER-Tavrida | ( 11h 36m 31.81s , +10d 5m 32.71s) | C | 60 | 15.6 | 1389 | 2019-04-21 22:01:35 | MASTER-Tavrida | ( 11h 37m 22.30s , +10d 9m 22.82s) | C | 60 | 15.8 | 1510 | 2019-04-21 22:03:35 | MASTER-Tavrida | ( 11h 36m 33.24s , +10d 5m 32.88s) | C | 60 | 15.4 | 1510 | 2019-04-21 22:03:35 | MASTER-Tavrida | ( 11h 37m 23.73s , +10d 9m 22.91s) | C | 60 | 15.2 | 2716 | 2019-04-21 22:23:41 | MASTER-Tavrida | ( 10h 57m 31.24s , + 6d 5m 37.70s) | C | 60 | 12.3 | 4211 | 2019-04-21 22:48:36 | MASTER-Tavrida | ( 11h 13m 37.24s , + 6d 5m 45.80s) | C | 60 | 12.8 | 4455 | 2019-04-21 22:52:41 | MASTER-Tavrida | ( 11h 20m 17.89s , +10d 5m 24.57s) | C | 60 | 17.0 | 4515 | 2019-04-21 22:52:41 | MASTER-Tavrida | ( 11h 20m 17.88s , +10d 5m 24.53s) | C | 180 | 18.2 | Coadd 4455 | 2019-04-21 22:52:41 | MASTER-Tavrida | ( 11h 21m 08.53s , +10d 9m 05.28s) | C | 60 | 16.6 | 4515 | 2019-04-21 22:52:41 | MASTER-Tavrida | ( 11h 21m 08.53s , +10d 9m 05.32s) | C | 180 | 17.9 | Coadd 4547 | 2019-04-21 22:54:13 | MASTER-Tavrida | ( 11h 21m 08.55s , +10d 9m 25.53s) | C | 60 | 17.6 | 4547 | 2019-04-21 22:54:13 | MASTER-Tavrida | ( 11h 20m 17.89s , +10d 5m 44.76s) | C | 60 | 17.8 | 4638 | 2019-04-21 22:55:44 | MASTER-Tavrida | ( 11h 20m 16.42s , +10d 5m 44.53s) | C | 60 | 17.7 | 4638 | 2019-04-21 22:55:44 | MASTER-Tavrida | ( 11h 21m 07.11s , +10d 9m 25.04s) | C | 60 | 17.3 | 4733 | 2019-04-21 22:57:18 | MASTER-IAC | ( 10h 57m 06.79s , +12d 6m 19.37s) | C | 60 | 18.8 | 4793 | 2019-04-21 22:57:18 | MASTER-IAC | ( 10h 57m 06.80s , +12d 6m 19.42s) | C | 180 | 19.4 | Coadd 4733 | 2019-04-21 22:57:18 | MASTER-IAC | ( 10h 48m 40.26s , +12d 9m 20.53s) | C | 60 | 18.5 | 4793 | 2019-04-21 22:57:18 | MASTER-IAC | ( 10h 48m 40.26s , +12d 9m 20.53s) | C | 180 | 19.2 | Coadd 4734 | 2019-04-21 22:57:20 | MASTER-Tavrida | ( 11h 8m 32.85s , +12d 5m 17.61s) | C | 60 | 18.0 | 4794 | 2019-04-21 22:57:20 | MASTER-Tavrida | ( 11h 8m 32.85s , +12d 5m 17.56s) | C | 180 | 18.8 | Coadd 4734 | 2019-04-21 22:57:20 | MASTER-Tavrida | ( 11h 9m 24.00s , +12d 8m 57.83s) | C | 60 | 17.6 | 4794 | 2019-04-21 22:57:20 | MASTER-Tavrida | ( 11h 9m 24.00s , +12d 8m 57.84s) | C | 180 | 18.1 | Coadd 4826 | 2019-04-21 22:58:51 | MASTER-Tavrida | ( 11h 8m 34.27s , +12d 5m 17.74s) | C | 60 | 18.1 | 4826 | 2019-04-21 22:58:51 | MASTER-Tavrida | ( 11h 9m 25.42s , +12d 8m 57.60s) | C | 60 | 17.6 | 4841 | 2019-04-21 22:59:07 | MASTER-IAC | ( 10h 57m 06.89s , +12d 6m 38.87s) | C | 60 | 18.7 | 4841 | 2019-04-21 22:59:07 | MASTER-IAC | ( 10h 48m 40.24s , +12d 9m 39.44s) | C | 60 | 18.6 | 4917 | 2019-04-21 23:00:23 | MASTER-Tavrida | ( 11h 8m 34.23s , +12d 5m 37.61s) | C | 60 | 18.3 | 4917 | 2019-04-21 23:00:23 | MASTER-Tavrida | ( 11h 9m 25.42s , +12d 9m 17.42s) | C | 60 | 17.7 | 4941 | 2019-04-21 23:00:46 | MASTER-IAC | ( 10h 48m 38.81s , +12d 9m 38.47s) | C | 60 | 18.7 | 4941 | 2019-04-21 23:00:46 | MASTER-IAC | ( 10h 57m 05.44s , +12d 6m 37.93s) | C | 60 | 18.8 | 5013 | 2019-04-21 23:01:59 | MASTER-Tavrida | ( 11h 24m 54.54s , +12d 5m 45.21s) | C | 60 | 18.3 | 5073 | 2019-04-21 23:01:59 | MASTER-Tavrida | ( 11h 24m 54.55s , +12d 5m 45.14s) | C | 180 | 18.7 | Coadd 5013 | 2019-04-21 23:01:59 | MASTER-Tavrida | ( 11h 25m 45.60s , +12d 9m 24.99s) | C | 60 | 17.8 | 5073 | 2019-04-21 23:01:59 | MASTER-Tavrida | ( 11h 25m 45.60s , +12d 9m 24.91s) | C | 180 | 18.1 | Coadd 5104 | 2019-04-21 23:03:30 | MASTER-Tavrida | ( 11h 24m 54.54s , +12d 5m 24.48s) | C | 60 | 17.4 | 5104 | 2019-04-21 23:03:30 | MASTER-Tavrida | ( 11h 25m 45.64s , +12d 9m 04.38s) | C | 60 | 17.3 | 5198 | 2019-04-21 23:05:04 | MASTER-Tavrida | ( 11h 24m 55.93s , +12d 5m 24.17s) | C | 60 | 17.9 | 5199 | 2019-04-21 23:05:04 | MASTER-Tavrida | ( 11h 25m 47.06s , +12d 9m 04.01s) | C | 60 | 17.3 | 5294 | 2019-04-21 23:06:40 | MASTER-Tavrida | ( 11h 37m 23.70s , +10d 9m 29.02s) | C | 60 | 18.0 | 5354 | 2019-04-21 23:06:40 | MASTER-Tavrida | ( 11h 37m 23.70s , +10d 9m 29.02s) | C | 180 | 18.7 | Coadd 5294 | 2019-04-21 23:06:40 | MASTER-Tavrida | ( 11h 36m 32.93s , +10d 5m 49.02s) | C | 60 | 18.2 | 5354 | 2019-04-21 23:06:40 | MASTER-Tavrida | ( 11h 36m 32.94s , +10d 5m 49.00s) | C | 180 | 18.9 | Coadd 5386 | 2019-04-21 23:08:11 | MASTER-Tavrida | ( 11h 36m 31.46s , +10d 5m 48.49s) | C | 60 | 18.3 | 5386 | 2019-04-21 23:08:11 | MASTER-Tavrida | ( 11h 37m 22.25s , +10d 9m 28.42s) | C | 60 | 17.9 | 5478 | 2019-04-21 23:09:43 | MASTER-Tavrida | ( 11h 36m 31.48s , +10d 5m 28.43s) | C | 60 | 18.3 | 5478 | 2019-04-21 23:09:43 | MASTER-Tavrida | ( 11h 37m 22.28s , +10d 9m 08.02s) | C | 60 | 17.8 | 7486 | 2019-04-21 23:43:11 | MASTER-IAC | ( 10h 48m 39.79s , +12d 9m 17.84s) | C | 60 | 18.5 | 7546 | 2019-04-21 23:43:11 | MASTER-IAC | ( 10h 48m 39.79s , +12d 9m 17.84s) | C | 180 | 19.1 | Coadd 7486 | 2019-04-21 23:43:12 | MASTER-IAC | ( 10h 57m 06.11s , +12d 6m 15.77s) | C | 60 | 18.8 | 7546 | 2019-04-21 23:43:12 | MASTER-IAC | ( 10h 57m 06.11s , +12d 6m 15.87s) | C | 180 | 19.4 | Coadd 7587 | 2019-04-21 23:44:52 | MASTER-IAC | ( 10h 48m 38.38s , +12d 9m 16.87s) | C | 60 | 18.4 | 7587 | 2019-04-21 23:44:52 | MASTER-IAC | ( 10h 57m 04.65s , +12d 6m 15.51s) | C | 60 | 18.7 | 7708 | 2019-04-21 23:46:53 | MASTER-IAC | ( 10h 48m 38.37s , +12d 8m 55.87s) | C | 60 | 18.4 | 7708 | 2019-04-21 23:46:54 | MASTER-IAC | ( 10h 57m 04.64s , +12d 5m 54.47s) | C | 60 | 18.7 | 7812 | 2019-04-21 23:48:38 | MASTER-IAC | ( 11h 5m 01.89s , +12d 9m 09.70s) | C | 60 | 18.5 | 7872 | 2019-04-21 23:48:38 | MASTER-IAC | ( 11h 5m 01.90s , +12d 9m 09.75s) | C | 180 | 19.0 | Coadd 7813 | 2019-04-21 23:48:38 | MASTER-IAC | ( 11h 13m 28.18s , +12d 6m 06.94s) | C | 60 | 18.8 | 7873 | 2019-04-21 23:48:38 | MASTER-IAC | ( 11h 13m 28.18s , +12d 6m 06.90s) | C | 180 | 19.6 | Coadd 7918 | 2019-04-21 23:50:23 | MASTER-IAC | ( 11h 13m 28.18s , +12d 6m 26.73s) | C | 60 | 18.8 | 7918 | 2019-04-21 23:50:23 | MASTER-IAC | ( 11h 5m 01.92s , +12d 9m 29.17s) | C | 60 | 18.5 | 8015 | 2019-04-21 23:52:01 | MASTER-IAC | ( 11h 5m 00.47s , +12d 9m 28.50s) | C | 60 | 18.6 | 8015 | 2019-04-21 23:52:01 | MASTER-IAC | ( 11h 13m 26.74s , +12d 6m 26.00s) | C | 60 | 18.8 | 8118 | 2019-04-21 23:53:43 | MASTER-IAC | ( 11h 16m 45.59s , +10d 9m 17.43s) | C | 60 | 18.4 | 8178 | 2019-04-21 23:53:43 | MASTER-IAC | ( 11h 16m 45.59s , +10d 9m 17.40s) | C | 180 | 19.1 | Coadd 8118 | 2019-04-21 23:53:43 | MASTER-IAC | ( 11h 25m 08.26s , +10d 6m 14.71s) | C | 60 | 18.8 | 8178 | 2019-04-21 23:53:43 | MASTER-IAC | ( 11h 25m 08.26s , +10d 6m 14.70s) | C | 180 | 19.5 | Coadd 8215 | 2019-04-21 23:55:21 | MASTER-IAC | ( 11h 16m 47.03s , +10d 9m 16.57s) | C | 60 | 18.4 | 8215 | 2019-04-21 23:55:21 | MASTER-IAC | ( 11h 25m 09.67s , +10d 6m 13.44s) | C | 60 | 18.8 | 8330 | 2019-04-21 23:57:15 | MASTER-IAC | ( 11h 16m 47.01s , +10d 9m 36.08s) | C | 60 | 18.4 | 8330 | 2019-04-21 23:57:15 | MASTER-IAC | ( 11h 25m 09.70s , +10d 6m 32.27s) | C | 60 | 18.8 | 8450 | 2019-04-21 23:59:15 | MASTER-IAC | ( 11h 29m 48.55s , +12d 6m 33.87s) | C | 60 | 18.7 | 8510 | 2019-04-21 23:59:15 | MASTER-IAC | ( 11h 29m 48.53s , +12d 6m 33.94s) | C | 180 | 19.3 | Coadd 8450 | 2019-04-21 23:59:16 | MASTER-IAC | ( 11h 21m 22.17s , +12d 9m 37.89s) | C | 60 | 18.4 | 8510 | 2019-04-21 23:59:16 | MASTER-IAC | ( 11h 21m 22.17s , +12d 9m 37.93s) | C | 180 | 19.1 | Coadd 8563 | 2019-04-22 00:01:09 | MASTER-IAC | ( 11h 21m 22.16s , +12d 9m 17.07s) | C | 60 | 18.4 | 8563 | 2019-04-22 00:01:09 | MASTER-IAC | ( 11h 29m 48.52s , +12d 6m 12.69s) | C | 60 | 18.7 | 8667 | 2019-04-22 00:02:52 | MASTER-IAC | ( 11h 21m 23.59s , +12d 9m 16.82s) | C | 60 | 18.4 | 8667 | 2019-04-22 00:02:52 | MASTER-IAC | ( 11h 29m 49.99s , +12d 6m 12.90s) | C | 60 | 18.7 | 8773 | 2019-04-22 00:04:38 | MASTER-IAC | ( 11h 10m 24.96s , +14d 9m 26.84s) | C | 60 | 18.5 | 8833 | 2019-04-22 00:04:38 | MASTER-IAC | ( 11h 10m 24.95s , +14d 9m 26.85s) | C | 180 | 19.3 | Coadd 8917 | 2019-04-22 00:07:03 | MASTER-IAC | ( 11h 10m 23.84s , +14d 9m 25.99s) | C | 60 | 18.4 | 8917 | 2019-04-22 00:07:03 | MASTER-IAC | ( 11h 18m 54.47s , +14d 6m 22.69s) | C | 60 | 18.9 | 8977 | 2019-04-22 00:07:03 | MASTER-IAC | ( 11h 18m 54.47s , +14d 6m 22.70s) | C | 180 | 19.5 | Coadd 9021 | 2019-04-22 00:08:46 | MASTER-IAC | ( 11h 10m 23.81s , +14d 9m 05.40s) | C | 60 | 18.5 | 9021 | 2019-04-22 00:08:46 | MASTER-IAC | ( 11h 18m 54.47s , +14d 6m 02.19s) | C | 60 | 18.9 | 9132 | 2019-04-22 00:10:37 | MASTER-IAC | ( 11h 18m 55.52s , +14d 6m 01.43s) | C | 60 | 18.9 | 9142 | 2019-04-22 00:10:47 | MASTER-IAC | ( 11h 10m 24.87s , +14d 9m 04.33s) | C | 60 | 18.5 | 10574 | 2019-04-22 00:34:39 | MASTER-IAC | ( 11h 5m 04.40s , +12d 9m 07.07s) | C | 60 | 18.5 | 10634 | 2019-04-22 00:34:39 | MASTER-IAC | ( 11h 5m 04.41s , +12d 9m 07.15s) | C | 180 | 19.0 | Coadd 10580 | 2019-04-22 00:34:45 | MASTER-IAC | ( 11h 13m 30.18s , +12d 6m 04.77s) | C | 60 | 18.8 | 10640 | 2019-04-22 00:34:45 | MASTER-IAC | ( 11h 13m 30.18s , +12d 6m 04.67s) | C | 180 | 19.3 | Coadd 10694 | 2019-04-22 00:36:39 | MASTER-IAC | ( 11h 5m 02.98s , +12d 9m 05.99s) | C | 60 | 18.2 | 10694 | 2019-04-22 00:36:39 | MASTER-IAC | ( 11h 13m 28.70s , +12d 6m 04.09s) | C | 60 | 18.5 | 10804 | 2019-04-22 00:38:29 | MASTER-IAC | ( 11h 5m 02.92s , +12d 8m 45.71s) | C | 60 | 18.5 | 10804 | 2019-04-22 00:38:29 | MASTER-IAC | ( 11h 13m 28.79s , +12d 5m 43.80s) | C | 60 | 18.8 | 10956 | 2019-04-22 00:41:02 | MASTER-IAC | ( 11h 16m 49.44s , +10d 8m 54.33s) | C | 60 | 18.3 | 11016 | 2019-04-22 00:41:02 | MASTER-IAC | ( 11h 16m 49.44s , +10d 8m 54.26s) | C | 180 | 19.1 | Coadd 10956 | 2019-04-22 00:41:02 | MASTER-IAC | ( 11h 25m 11.82s , +10d 5m 52.58s) | C | 60 | 18.8 | 11016 | 2019-04-22 00:41:02 | MASTER-IAC | ( 11h 25m 11.82s , +10d 5m 52.57s) | C | 180 | 19.4 | Coadd 11059 | 2019-04-22 00:42:44 | MASTER-IAC | ( 11h 16m 49.46s , +10d 9m 13.39s) | C | 60 | 18.4 | 11059 | 2019-04-22 00:42:44 | MASTER-IAC | ( 11h 25m 11.76s , +10d 6m 11.68s) | C | 60 | 18.7 | 11162 | 2019-04-22 00:44:27 | MASTER-IAC | ( 11h 16m 48.00s , +10d 9m 12.66s) | C | 60 | 18.5 | 11162 | 2019-04-22 00:44:27 | MASTER-IAC | ( 11h 25m 10.38s , +10d 6m 10.80s) | C | 60 | 18.7 | 11274 | 2019-04-22 00:46:19 | MASTER-IAC | ( 11h 21m 24.61s , +12d 8m 54.66s) | C | 60 | 18.5 | 11334 | 2019-04-22 00:46:19 | MASTER-IAC | ( 11h 21m 24.61s , +12d 8m 54.68s) | C | 180 | 19.1 | Coadd 11274 | 2019-04-22 00:46:19 | MASTER-IAC | ( 11h 29m 50.63s , +12d 5m 51.99s) | C | 60 | 18.7 | 11334 | 2019-04-22 00:46:19 | MASTER-IAC | ( 11h 29m 50.61s , +12d 5m 52.04s) | C | 180 | 19.4 | Coadd 11383 | 2019-04-22 00:48:09 | MASTER-IAC | ( 11h 21m 26.04s , +12d 8m 53.97s) | C | 60 | 18.3 | 11383 | 2019-04-22 00:48:09 | MASTER-IAC | ( 11h 29m 52.03s , +12d 5m 51.29s) | C | 60 | 18.7 | 11488 | 2019-04-22 00:49:54 | MASTER-IAC | ( 11h 21m 26.05s , +12d 9m 13.30s) | C | 60 | 18.4 | 11489 | 2019-04-22 00:49:54 | MASTER-IAC | ( 11h 29m 51.98s , +12d 6m 10.72s) | C | 60 | 18.7 | 11595 | 2019-04-22 00:51:40 | MASTER-IAC | ( 11h 10m 26.31s , +14d 9m 03.54s) | C | 60 | 18.3 | 11595 | 2019-04-22 00:51:40 | MASTER-IAC | ( 11h 18m 56.45s , +14d 6m 01.43s) | C | 60 | 18.8 | 11655 | 2019-04-22 00:51:40 | MASTER-IAC | ( 11h 18m 56.45s , +14d 6m 01.44s) | C | 180 | 19.5 | Coadd 11655 | 2019-04-22 00:51:40 | MASTER-IAC | ( 11h 10m 26.30s , +14d 9m 03.57s) | C | 180 | 19.1 | Coadd 11699 | 2019-04-22 00:53:24 | MASTER-IAC | ( 11h 10m 26.31s , +14d 8m 42.73s) | C | 60 | 18.4 | 11699 | 2019-04-22 00:53:25 | MASTER-IAC | ( 11h 18m 56.42s , +14d 5m 40.44s) | C | 60 | 18.8 | 11811 | 2019-04-22 00:55:16 | MASTER-IAC | ( 11h 10m 27.39s , +14d 8m 42.11s) | C | 60 | 18.4 | 11811 | 2019-04-22 00:55:16 | MASTER-IAC | ( 11h 18m 57.49s , +14d 5m 40.02s) | C | 60 | 18.8 | 18337 | 2019-04-22 02:43:02 | MASTER-OAFA | ( 16h 17m 22.24s , -74d 11m 48.35s) | C | 180 | 13.5 | 21201 | 2019-04-22 03:30:46 | MASTER-OAFA | ( 16h 17m 24.72s , -74d 10m 56.97s) | C | 180 | 17.3 | 21822 | 2019-04-22 03:41:08 | MASTER-OAFA | ( 16h 17m 25.60s , -74d 12m 21.71s) | C | 180 | 16.8 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24146 SUBJECT: LIGO/Virgo S190421ar: Fermi-GBM Observations DATE: 19/04/22 19:19:06 GMT FROM: Peter Veres at UAH P. Veres (UAH), C. M. Hui (NASA/MSFC) and A. Goldstein (USRA) report on behalf of the Fermi-GBM Team and the GBM-LIGO/Virgo group: "At the time of the S190421ar GW trigger (2019-04-21 21:38:56.41 UT), based on the initial BAYESTAR skymap, Fermi-GBM was observing 78.6% of the localization probability region. There was no Fermi-GBM onboard trigger around the event time of the LIGO/Virgo detection (GCN 24141). 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 for the +/-30 s interval around merger time, and also identified no counterpart candidates. We therefore set upper limits on impulsive gamma-ray emission considering the 90% credible region of the GW localization. Using the representative soft, normal, and hard GRB-like spectral 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 ------------------------------------ 0.1 s: 4.3-6.6 8.5-11 26-29 1.0 s: 1.3-2.1 2.7-3.5 7.7-8.6 10 s: 0.4-0.6 0.8-1.1 2.4-2.6 Assuming the mean luminosity distance of ~2300 Mpc (z=0.42) from the GW detection, we estimate intrinsic luminosity upper limits of (4.1-67)E49 erg/s for the soft template, (7.1-98)E49 erg/s for the normal template, and (3.6-44)E50 erg/s for the hard template over the 1 keV-10 MeV energy range." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24152 SUBJECT: LIGO/Virgo S190421ar: INTEGRAL prompt observation DATE: 19/04/23 05:40:08 GMT FROM: Alexander Lutovinov at Space Research Inst.,IKI D. Götz (CEA, France), A. 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 combination of INTEGRAL all-sky detectors: SPI/ACS, IBIS/Veto, and IBIS (Savchenko et al. 2017, A&A 603, A46) we have performed a search for a prompt gamma-ray counterpart of S190421ar (GCN 24141). At the time of the event (2019-04-21 21:38:56 UTC, hereafter T0), INTEGRAL was operating in nominal mode. The peak of the event localization probability was at an angle of 49 deg with respect to the spacecraft pointing axis. This orientation implies strongly suppressed (19% of optimal) response of ISGRI, strongly suppressed (40% of optimal) response of IBIS/Veto, and near-optimal (77% of optimal) response of SPI-ACS. For this first report, we use only 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 (Savchenko et al. 2012, A&A 541A, 122S), IBIS, and IBIS/Veto data. We do not detect any significant counterparts and estimate a 3-sigma upper limit on the 75-2000 keV fluence of 1.9e-07 erg/cm^2 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 ~1.6e-07 (5.8e-08) erg/cm^2/s at 1 s (8 s) time scale in 75-2000 keV energy range. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24153 SUBJECT: LIGO/Virgo S190421ar: MAXI/GSC Observations DATE: 19/04/23 05:58:11 GMT FROM: Motoko Serino at RIKEN/MAXI M. Serino, S. Sugita (AGU), H. Negoro (Nihon U.), M. Sugizaki, N. Kawai (Tokyo Tech), M. Nakajima, W. Maruyama, M. Aoki, K. Kobayashi (Nihon U.), S. Nakahira, T. Mihara, T. Tamagawa, M. Matsuoka (RIKEN), T. Sakamoto, H. Nishida, A. Yoshida (AGU), Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai, T. Sato (Chuo U.), M. Shidatsu (Ehime U.), Y. Tachibana, K. Morita, M. Oeda, K. Shiraishi (Tokyo Tech), S. Ueno, H. Tomida, M. Ishikawa, Y. Sugawara, N. Isobe, R. Shimomukai, M. Tominaga (JAXA), Y. Ueda, A. Tanimoto, T. Morita, S. Yamada, S. Ogawa (Kyoto U.), H. Tsunemi, T. Yoneyama, K. Asakura, S. Ide (Osaka U.), M. Yamauchi, S. Iwahori, Y. Kurihara (Miyazaki U.), T. Kawamuro (NAOJ), K. Yamaoka (Nagoya U.), Y. Kawakubo (LSU) report on behalf of the MAXI team: We examined the MAXI/GSC all-sky X-ray images (2-20 keV) obtained in the orbit after the LVC trigger S190421ar at 2019-04-21 21:38:56 UTC (GCN 24141). At the trigger time of S190421ar, the high-voltage of MAXI/GSC was on, and it was turned off at T0+78 sec. The one-orbit (92 min) scan of GSC covered 63% of the 90% error region of the bayestar skymap from 21:38:56 to 23:10:54 UTC (T0 to T0+5518 sec). No significant new source was found in the error region at the one-orbit scan. The 1-sigma averaged upper limit obtained from the scan was 18 mCrab at 4-10 keV. If you require information of X-ray flux by MAXI/GSC at specific coordinates, please contact the submitter of this circular by email. -- Motoko SERINO //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24156 SUBJECT: LIGO/Virgo S190421ar/G330308: ANTARES neutrino search DATE: 19/04/23 14:55:34 GMT FROM: Damien Dornic at CPPM,France M. Ageron (CPPM/CNRS), B. Baret (APC/CNRS), A. Coleiro (APC/Universite Paris Diderot), M. Colomer (APC/Universite Paris Diderot)), D. Dornic (CPPM/CNRS), A. Kouchner (APC/Universite Paris Diderot), T. Pradier (IPHC/Universite de Strasbourg) report on behalf of the ANTARES Collaboration: Using on-line data from the ANTARES detector, we have performed a follow-up analysis of the recently reported LIGO/Virgo G330308/S190421ar event using the 90% contour of the probability map provided by the GW interferometers at event time. The ANTARES visibility at the time of the alert, together with the 50% and 90% contours of the probability map are shown in https://www.cppm.in2p3.fr/~dornic/events_runo3/S190421ar.png . Considering the location probability provided by the LIGO/Virgo collaborations, there is a 52% 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 (2019-04-21 21:38:56 UT) and in the 90% contour of the G330308/S190421ar event. The expected number of atmospheric background events in the region visible by ANTARES is 4.0e-4 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 2.9e-3 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: 24158 SUBJECT: LIGO/Virgo S190421ar: Swift/BAT Counterpart Search DATE: 19/04/23 16:09:11 GMT FROM: Amy Lien at GSFC D. M. Palmer (LANL), S. D. Barthelmy (NASA/GSFC), A. Y. Lien (GSFC/UMBC), T. Sakamoto (AGU), A. A. Breeveld (MSSL-UCL), A. P. Beardmore (U. Leicester), D. N. Burrows (PSU), S. Campana (INAF-OAB), S. B. Cenko (NASA/GSFC),G. Cusumano (INAF-IASF PA), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB), V. D'Elia(ASDC), 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), B. Mingo (U. Leicester), J. A. Nousek (PSU), S. R. Oates (Uni. of Warwick), P. T. O'Brien (U. Leicester), J. P. Osborne (U. Leicester), C. Pagani (U. Leicester), K. L. Page (U.Leicester), M. Perri (ASDC), J. L. Racusin (NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU), M. H. Siegel (PSU), G. Tagliaferri (INAF-OAB), 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 S190421ar (LIGO/VIRGO Collaboration GCN Circ. 24141), where T0 is the LVC trigger time (2019-04-21T21:38:56 UTC). The center of the BAT FOV at T0 is RA = 183.218 deg, DEC = 6.982 deg, ROLL = 313.598 deg. The BAT Field of View (>10% partial coding) covers 23.09% of the integrated LVC localization probability. Within T0 +/- 100 s, no significant detections (signal-to-noise ratio >~ 5 sigma) are found in the BAT raw light curves with time bins of 64 ms, 1 s, and 1.6 s, respectively. Assuming an on-axis (100% coded) short GRB with a typical spectrum in the BAT energy range (i.e., a simple power-law model with a power-law index of -1.32, Lien & Sakamoto et al. 2016), the 5-sigma upper limit in the 1-s binned light curve corresponds to a flux upper limit (15-350 keV) of ~ 8.46 x 10^-8 erg/s/cm^2. BAT retains decreased, but significant, sensitivity to rate increases for gamma-ray events outside of its FOV. About 76.91% 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 of those within the FOV. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24160 SUBJECT: LIGO/Virgo S190421ar: Lick/KAIT Follow-Up Observations DATE: 19/04/23 20:11:52 GMT FROM: Weikang Zheng at UC Berkeley WeiKang Zheng, Keto Zhang, Sergiy Vasylyev, Benjamin Stahl 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 field of the gravitational-wave event S190421ar (GCN 24141) detected by LIGO/Virgo. More than one thousand galaxies were selected from the Glade catalog (http://aquarius.elte.hu/glade/) according to their priority score. KAIT observed 159 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 03:52:11, Apr. 23 UT, about 30.2 hrs after the trigger, and the last image at 08:22:03 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(Apr. 23) RA (J2000) Dec G0799947 03:52:11 10:54:51.770 +16:44:52.30 G0777765 03:53:27 11:36:36.370 +13:34:26.90 G1614050 03:54:37 11:31:25.220 +09:02:54.50 G0662161 03:55:53 12:23:41.600 +05:31:46.10 G0670167 03:57:04 12:43:12.360 -02:15:10.40 G0569866 03:58:23 13:22:59.920 -27:44:31.80 G0791468 03:59:42 12:36:47.150 +03:05:42.70 G1851120 04:00:56 12:18:55.660 +00:19:43.20 G0895821 04:02:05 12:22:16.060 +04:31:33.30 G0783735 04:03:26 11:04:00.650 +17:13:36.30 G0729367 04:20:19 10:44:27.730 +18:57:32.10 G0003201 04:21:38 11:41:44.730 +22:20:22.20 G0705729 04:23:05 13:27:54.820 -31:29:40.90 G0748624 04:35:47 12:16:40.240 +08:01:36.90 G0750982 04:37:01 13:05:43.400 -12:54:42.70 G0694610 04:38:27 10:49:12.360 +19:50:19.20 G0704658 04:39:56 13:34:40.370 -31:46:12.20 G0685127 04:41:15 12:16:12.140 +04:27:24.80 G0623925 04:42:38 10:29:08.400 +20:40:19.80 G0707742 04:44:01 12:32:43.950 -01:07:01.70 G0745190 04:45:15 13:02:06.340 -08:16:15.40 G0679095 04:46:26 12:56:30.090 -13:44:37.80 G0830299 04:47:37 12:46:29.040 -05:12:22.80 G0707185 04:48:49 13:11:17.330 -14:38:04.60 G0745128 04:50:05 12:20:46.740 +12:18:53.30 G0571301 04:51:18 12:35:37.390 -02:25:40.20 G0594576 04:52:40 11:08:18.590 +15:45:30.50 G0584223 04:53:49 11:13:19.340 +16:29:39.00 G0824991 04:56:40 11:13:32.460 +15:58:13.30 G0671792 04:57:49 11:10:53.670 +13:33:34.70 G0807427 04:59:01 10:53:52.320 +16:52:55.50 G0592304 05:00:12 11:20:44.630 +13:51:29.30 G1377354 05:01:25 11:43:59.630 +12:58:40.30 G0398790 05:02:46 13:04:52.160 -16:39:23.90 G0949356 05:04:09 11:08:05.740 +18:11:46.70 G0697369 05:05:31 12:36:10.090 -00:19:38.50 G0632479 05:06:40 12:35:36.070 +01:48:20.80 G1285927 05:07:54 13:00:57.930 -12:05:43.80 G0715500 05:09:07 13:21:43.230 -26:45:59.60 G0752413 05:11:43 11:49:53.440 +11:08:12.10 G0615964 05:13:01 10:57:23.620 +16:29:20.40 G0793836 05:44:49 11:52:32.440 +04:59:38.90 G1299111 05:46:08 13:00:35.680 -16:03:57.40 G1002056 05:47:30 11:33:26.660 +13:53:39.30 G0751169 05:48:47 10:36:47.600 +20:36:18.50 G0549931 05:50:07 11:43:06.150 +08:52:23.30 G0552033 05:51:26 12:56:29.870 -07:52:21.40 G0700845 05:52:39 12:20:15.130 +05:09:47.10 G0648779 05:54:02 10:56:48.610 +14:45:44.70 G0677192 05:56:42 13:27:53.080 -27:14:38.30 G0642481 05:57:55 13:02:38.560 -13:47:46.40 G0765485 05:59:09 13:34:10.570 -22:41:53.20 G0652477 06:00:37 11:00:37.720 +16:28:17.80 G0637511 06:02:00 12:45:56.710 -00:08:55.00 G1257022 06:03:21 11:15:57.220 +16:43:57.60 G0699404 06:04:37 10:48:53.300 +19:47:28.90 G0802935 06:05:57 12:04:27.470 +08:15:45.70 G0798113 06:07:13 12:36:06.330 -00:57:54.90 G0689268 06:08:31 13:22:31.160 -30:48:31.80 G0283238 06:09:40 13:13:16.230 -29:27:48.50 G1884552 06:11:01 12:28:29.520 +08:43:06.50 G0747346 06:12:14 12:48:54.700 -03:43:57.30 G0008302 06:13:23 12:44:53.230 +00:03:40.50 G1183363 06:14:48 11:11:57.520 +13:33:45.70 G0586559 06:16:03 11:49:48.240 +09:53:18.60 G0486241 06:17:20 12:30:12.110 +00:42:40.40 G0822058 06:18:39 11:18:45.400 +14:49:20.30 G1226448 06:19:56 11:58:46.710 +08:12:05.60 G0659898 06:21:11 12:39:40.780 -03:04:20.30 G0398739 06:22:25 12:13:04.500 +13:05:53.40 G0847413 06:24:08 10:55:56.830 +17:36:17.60 G0572104 06:25:25 10:31:51.710 +19:37:36.30 G0667230 06:26:44 11:22:47.310 +11:37:57.20 G0807454 06:28:05 12:52:17.600 -05:35:46.10 G0751534 06:29:22 12:10:15.470 +05:29:04.70 G0620788 06:30:45 13:15:12.190 -33:52:27.60 G0704596 06:31:57 13:28:34.900 -31:29:23.50 G0773860 06:33:24 10:59:06.700 +17:01:17.60 G0623612 06:34:47 12:39:37.830 +01:22:02.30 G0711053 06:36:05 13:22:35.440 -26:44:58.10 G0704591 06:37:26 12:36:01.190 +01:41:32.40 G0560656 06:38:48 10:45:25.210 +18:23:09.10 G0767272 06:40:18 13:32:37.260 -33:02:07.80 G1383828 06:41:41 12:00:43.010 +08:31:29.30 G0695335 06:42:58 12:46:51.830 -08:31:54.40 G0642730 06:44:09 12:53:58.760 -02:35:01.20 G0775517 06:45:29 11:22:01.510 +15:22:34.80 G0610251 06:46:47 12:17:54.630 +08:15:07.80 G0714185 06:48:04 12:45:36.610 -12:05:58.30 G0783442 06:49:27 11:04:04.880 +17:05:04.30 G0470847 06:50:52 13:29:00.620 -25:57:19.90 G0801447 06:52:12 12:20:36.100 +05:17:27.50 G1444829 06:54:41 11:47:18.900 +11:04:15.10 G0681551 06:55:52 12:03:42.030 +09:47:48.40 G1075426 06:57:09 11:07:27.310 +14:15:32.60 G1860164 06:58:37 13:28:54.340 -34:06:05.90 G0597443 07:00:03 11:10:52.110 +14:57:43.10 G0654232 07:01:12 11:07:52.050 +14:05:55.60 G0762634 07:02:37 13:35:35.590 -22:16:29.10 G1178329 07:04:20 11:20:46.690 +15:43:27.60 G0779980 07:05:42 12:51:03.280 -01:38:43.10 G0837893 07:07:04 11:05:36.650 +17:45:13.70 G0557210 07:08:27 12:45:39.650 -05:32:38.70 G0589937 07:09:42 12:07:56.570 +10:10:34.70 G0680269 07:11:03 10:47:26.470 +18:25:46.10 G0717254 07:12:12 10:46:40.650 +20:03:46.00 G0743648 07:13:29 11:33:07.120 +11:36:11.60 G0738566 07:14:45 12:13:11.610 +05:26:04.70 G0791862 07:16:01 11:36:53.980 +13:35:49.40 G0623238 07:17:10 11:44:51.920 +12:21:33.50 G0568487 07:18:28 12:49:59.340 -01:15:53.60 G0756486 07:19:38 12:46:08.660 -02:04:47.70 G0734272 07:21:04 10:36:48.090 +19:56:44.60 G0707456 07:22:30 12:53:07.570 -09:35:34.60 G0567747 07:23:57 10:32:31.270 +19:36:24.40 G0679832 07:25:29 13:32:14.340 -33:37:45.20 G0797243 07:26:51 12:15:38.570 +05:21:37.70 G0768732 07:28:10 12:56:19.110 -22:57:29.40 G0644499 07:29:29 11:42:44.000 +09:35:07.00 G0603111 07:30:48 10:50:04.830 +18:16:52.00 G0612708 07:32:09 12:17:44.810 +04:06:30.70 G0403675 07:33:21 12:37:04.400 +00:49:12.20 G0706192 07:34:32 12:27:03.250 -00:25:14.90 G1060259 07:35:46 11:47:45.470 +07:31:34.40 G0589723 07:37:09 13:29:15.460 -34:08:22.80 G1307108 07:38:30 12:25:41.090 +04:09:51.20 G0737025 07:39:55 10:36:50.970 +19:57:32.70 G0756551 07:41:21 12:47:31.420 -00:44:55.80 G0782549 07:42:49 10:23:40.920 +19:17:55.70 G0586829 07:44:44 12:44:29.730 -04:50:13.40 G0785594 07:45:55 12:39:14.470 +01:01:52.90 G0592705 07:47:11 13:04:03.230 -17:52:33.80 G1108585 07:48:30 11:58:27.440 +08:34:10.30 G0621576 07:49:47 12:47:17.380 -05:24:05.00 G0625796 07:51:03 11:57:04.190 +05:24:42.50 G0604805 07:52:14 11:53:12.530 +10:15:23.80 G0780552 07:53:30 11:29:00.590 +12:25:25.80 G0768066 07:54:39 11:30:01.510 +14:52:17.30 G0827712 07:55:49 11:34:17.830 +14:40:50.50 G0612666 07:57:04 12:02:13.270 +09:37:12.60 G0812028 07:58:23 10:55:02.400 +16:42:31.10 G0650680 07:59:52 13:25:59.840 -28:59:15.70 G0773184 08:01:16 11:58:02.910 +09:58:47.80 G0770039 08:02:36 13:19:33.230 -21:32:32.90 G0719344 08:03:49 12:54:50.530 -09:56:11.00 G0685552 08:05:07 12:22:26.060 -03:19:35.90 G0747374 08:06:32 10:43:38.120 +15:38:52.20 G0744444 08:07:49 11:44:08.240 +09:20:42.60 G0643448 08:09:09 12:50:51.000 -04:44:59.30 G0524127 08:10:24 12:16:10.070 +07:25:38.70 G1286055 08:11:44 11:15:57.230 +16:43:08.50 G0770930 08:12:59 11:50:06.660 +10:56:13.30 G0763265 08:14:16 12:34:49.710 +01:46:23.90 G0710642 08:15:27 12:49:20.750 -05:19:59.80 G0749738 08:16:44 11:37:30.140 +13:07:21.50 G0792334 08:18:08 13:30:53.300 -31:24:45.10 G0459407 08:19:32 11:42:01.600 +12:06:11.70 G0717476 08:20:44 11:30:27.800 +13:06:48.00 G0755671 08:22:03 12:39:16.330 -04:52:51.00 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24162 SUBJECT: LIGO/Virgo S190421ar: TAROT-GRANDMA observation report. DATE: 19/04/24 09:57:13 GMT FROM: Martin Blazek at HETH/IAA-CSIC M. Blazek (IAA/CSIC), M. Boer (Artemis), N. Christensen (Artemis), L. Eymar (Artemis), A. Klotz (IRAP), R. Laugier (Artemis), K. Noysena (Artemis, IRAP), S. Antier (APC), S. Basa (LAM), D. Corre (LAL), M. Coughlin (Caltech), D. Coward (OzGrav-UWA), J.G. Ducoin (LAL), B. Gendre (OzGrav-UWA), P. Hello (LAL), C. Lachaud (APC), N. Leroy (LAL), D. Turpin (NAOC), X. Wang (THU) Report on behalf of the TAROT network and GRANDMA collaborations. We performed tiled observations of LIGO/VIRGO event S190421ar (GCN #24141) with the TAROT-Reunion (Les Makes Observatory, La Réunion Island, France) telescope operating in clear filter. The observation started on 04/22/19 17:19:22 UTC which corresponds approximately to 19.7 hours after the GW trigger time. We performed the following tiled observations : +---------------------+---------------------+---------+---------+-------+ | Tstart | Tend | RA | DEC | Proba | | [UTC] | [UTC] | [deg] | [deg] | [%] | |---------------------+---------------------+---------+---------+-------| | 2019-04-22 17:19:22 | 2019-04-23 01:37:03 | 205.714 | -60 | 2.6 | | 2019-04-22 17:32:30 | 2019-04-23 01:05:10 | 204.179 | -38.571 | 2.5 | | 2019-04-22 17:44:37 | 2019-04-23 01:18:28 | 203.774 | -51.429 | 2.4 | | 2019-04-22 18:00:09 | 2019-04-22 20:18:14 | 204.828 | -47.143 | 2.8 | | 2019-04-22 19:39:33 | 2019-04-23 00:11:50 | 210 | -55.714 | 2.6 | | 2019-04-22 19:52:45 | 2019-04-22 22:12:51 | 203.226 | -42.857 | 2.5 | | 2019-04-22 20:50:10 | 2019-04-22 22:26:08 | 210.566 | -51.429 | 2.3 | +---------------------+---------------------+---------+---------+-------+ The Probability refers to the 2D spatial probability of the GW skymap enclosed in a given tile. Each tile is 4.2x4.2 degrees. These observations cover about 17% of the cumulative probability of the skymap. The typical 3-sigma limiting magnitude for a two minutes exposure is 17 mag. The coverage map is available at: grandma-owncloud.lal.in2p3.fr/index.php/s/0O3ZreoLvm7VIOD Optical transient candidates will be sent through another GCN circular depending on our data 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: 24165 SUBJECT: LIGO-Virgo S190421ar:Insight-HXMT/HE observation DATE: 19/04/25 02:56:19 GMT FROM: Shuo Xiao at IHEP S. Xiao, C. K. Li, X. B. Li, G. 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: In response to the LIGO-Virgo GW event S190421ar T0 = 2019-04-21 21:38:56 (UTC; GCN #24141), analysis of HXMT/HE data shows that the satellite at T0 was in the South Atlantic Anomaly (SAA). 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 telescope. Insight-HXMT is the first Chinese space X-ray telescope, which was funded jointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information could be found at: http://www.hxmt.org.