//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30090 SUBJECT: GRB 210528A: Fermi GBM Final Real-time Localization DATE: 21/05/28 14:14:06 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM The Fermi GBM team reports the detection of a likely LONG GRB At 14:03:46 UT on 28 May 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210528A (trigger 643903431.162588 / 210528586). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 134.1, Dec = -16.3 (J2000 degrees, equivalent to J2000 08h 56m, -16d 18'), with a statistical uncertainty of 1.9 degrees. The angle from the Fermi LAT boresight is 55.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210528586/quicklook/glg_skymap_all_bn210528586.png The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210528586/quicklook/glg_healpix_all_bn210528586.fit The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210528586/quicklook/glg_lc_medres34_bn210528586.gif //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30091 SUBJECT: GRB 210528A: BALROG localization (Fermi Trigger 643903431 / GRB 210528586) DATE: 21/05/28 14:24:25 GMT FROM: Jochen Greiner at MPE,Garching F. Kunzweiler, B. Biltzinger, F. Berlato, J. Burgess & J. Greiner (all MPE Garching) report: The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger 643903431 at 14:03:46 on 28 May 2021 were automatically fitted for spectrum and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427; Berlato et al. 2019, ApJ 873, 60). The best-fit position (1 sigma statistical errors) is: RA(2000.0) = 137.1+/-2.2 deg Decl.(2000.0) = -14.0+/-2.4 deg We estimate an additional systematic error of 2 deg. Further details are available at: https://grb.mpe.mpg.de/grb/GRB210528586/ The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB210528586/healpix The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB210528586/json //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30093 SUBJECT: Fermi GRB 210528A: Global MASTER-Net observations report DATE: 21/05/28 23:15:13 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, D. Cheryasov (Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA), 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-IAC robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Spain (IAC Teide Observatory) started inspect of the Fermi GRB 210528A ( Fermi GBM team, GCN 30090) errorbox 23846 sec after notice time and 23874 sec after trigger time at 2021-05-28 20:41:40 UT, with upper limit up to 18.1 mag. Observations started at twilight. The observations began at zenith distance = 61 deg. The sun altitude is -10.4 deg. The galactic latitude b = 19 deg., longitude l = 244 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1623301 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 23904 | 2021-05-28 20:41:40 | MASTER-IAC | (09h 02m 44.74s , -13d 49m 49.9s) | C | 60 | 16.3 | 24064 | 2021-05-28 20:44:20 | MASTER-IAC | (09h 07m 35.44s , -15d 45m 51.5s) | C | 60 | 16.7 | 24224 | 2021-05-28 20:46:59 | MASTER-IAC | (09h 00m 12.10s , -15d 50m 05.1s) | C | 60 | 17.2 | 24224 | 2021-05-28 20:46:59 | MASTER-IAC | (08h 51m 50.12s , -15d 44m 39.9s) | C | 60 | 16.6 | 24463 | 2021-05-28 20:50:59 | MASTER-IAC | (08h 55m 21.79s , -13d 57m 05.7s) | C | 60 | 17.5 | 24463 | 2021-05-28 20:50:59 | MASTER-IAC | (08h 47m 03.96s , -13d 51m 40.4s) | C | 60 | 17.0 | 24623 | 2021-05-28 20:53:38 | MASTER-IAC | (09h 05m 43.99s , -17d 44m 47.2s) | C | 60 | 17.8 | 24623 | 2021-05-28 20:53:38 | MASTER-IAC | (08h 57m 16.72s , -17d 39m 23.2s) | C | 60 | 17.4 | 24863 | 2021-05-28 20:57:39 | MASTER-IAC | (09h 02m 46.24s , -13d 50m 39.8s) | C | 60 | 17.5 | 25423 | 2021-05-28 21:06:59 | MASTER-IAC | (09h 07m 34.43s , -15d 44m 11.1s) | C | 60 | 17.9 | 28711 | 2021-05-28 22:01:46 | MASTER-IAC | (09h 00m 07.99s , -15d 52m 31.3s) | C | 60 | 18.1 | 28950 | 2021-05-28 22:05:46 | MASTER-IAC | (08h 55m 24.26s , -13d 58m 30.1s) | C | 60 | 18.1 | 29110 | 2021-05-28 22:08:26 | MASTER-IAC | (09h 05m 38.03s , -17d 45m 24.2s) | C | 60 | 18.1 | 29670 | 2021-05-28 22:17:46 | MASTER-IAC | (09h 00m 15.02s , -15d 50m 52.6s) | C | 60 | 18.0 | 29910 | 2021-05-28 22:21:45 | MASTER-IAC | (08h 55m 27.00s , -13d 57m 44.5s) | C | 60 | 17.9 | 30070 | 2021-05-28 22:24:25 | MASTER-IAC | (09h 05m 44.96s , -17d 46m 24.8s) | C | 60 | 18.0 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30095 SUBJECT: MAXI GRB210528.95: Global MASTER-Net observations report DATE: 21/05/29 00:51:13 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, D. Cheryasov (Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA), 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-IAC robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Spain (IAC Teide Observatory) started inspect of the MAXI GRB210528.95 (trigger No 362758075,15h 58m 09.36s , +05d 58m 58.8s, R=1) errorbox 10 sec after notice time and 4707 sec after trigger time at 2021-05-29 00:10:22 UT, with upper limit up to 18.8 mag. The observations began at zenith distance = 23 deg. The sun altitude is -39.0 deg. The galactic latitude b = 40 deg., longitude l = 16 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1623577 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 4798 | 2021-05-29 00:10:22 | MASTER-IAC | (15h 57m 01.56s , +06d 02m 14.3s) | P| | 180 | 18.5 | 4798 | 2021-05-29 00:10:22 | MASTER-IAC | (15h 56m 10.28s , +06d 08m 43.9s) | P- | 180 | 18.3 | 4998 | 2021-05-29 00:13:42 | MASTER-IAC | (15h 57m 09.19s , +06d 02m 16.4s) | P| | 180 | 18.7 | 4998 | 2021-05-29 00:13:42 | MASTER-IAC | (15h 56m 17.67s , +06d 08m 46.0s) | P- | 180 | 18.3 | 5198 | 2021-05-29 00:17:02 | MASTER-IAC | (15h 57m 06.12s , +06d 03m 54.3s) | P| | 180 | 18.7 | 5198 | 2021-05-29 00:17:02 | MASTER-IAC | (15h 56m 14.54s , +06d 10m 23.3s) | P- | 180 | 18.4 | 5398 | 2021-05-29 00:20:22 | MASTER-IAC | (15h 57m 06.18s , +06d 02m 37.0s) | P| | 180 | 18.8 | 5398 | 2021-05-29 00:20:22 | MASTER-IAC | (15h 56m 14.59s , +06d 09m 05.6s) | P- | 180 | 18.4 | The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30098 SUBJECT: GRB 210528A: AstroSat CZTI detection DATE: 21/05/29 14:46:52 GMT FROM: Gaurav Waratkar at IIT,Bombay P. Sawant (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), S. Gupta (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al, 2020, arxiv:2011.07067) showed detection of a short GRB 210528A, which was also detected by Fermi-GBM (GCN #30090). The source was clearly detected in the 20 - 200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2021-05-28 14:03:45.5 UT. The measured peak count rate associated with the burst is 682 (+186, -164) cts/s above the background in the combined data of all four quadrants, with a total of 307 (+69, -65) cts. The local mean background count rate was 547 (+9, -11) cts/s. Using cumulative rates, we measure a T90 of 0.89 (+0.2, -0.3) s. It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100 - 500 keV energy range. CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb [1]. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project. Links: ------ [1] http://astrosat.iucaa.in/czti/?q=grb //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30099 SUBJECT: GRB 210528A: Fermi GBM detection DATE: 21/05/29 15:34:40 GMT FROM: Peter Veres at UAH P. Veres and C. Meegan (both UAH) report on behalf of the Fermi GBM Team: "At 14:03:46.16 UT on 28 May 2021, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 210528A (trigger 643903431 / 210528586). The on-ground calculated location, using the GBM trigger data, is reported in GCN #30090. The GBM light curve consists of a strong pulse with some overlapping structure and a duration (T90) of about 1 s (50-300 keV). The time-averaged spectrum from T0-0.3 s to T0+1.3 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.47 +/- 0.06 and the cutoff energy, parameterized as Epeak, is 210 +/- 9 keV. The event fluence (10-1000 keV) in this time interval is (3.90 +/- 0.12)E-6 erg/cm^2. The 64ms peak photon flux measured starting from T0 + 0.256 s in the 10-1000 keV band is 31.7 +/- 2.0 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"