//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30071 SUBJECT: GRB 210524A: Fermi GBM Final Real-time Localization DATE: 21/05/24 05:10:21 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM The Fermi GBM team reports the detection of a likely LONG GRB At 04:59:59 UT on 24 May 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210524A (trigger 643525204.091768 / 210524208). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 337.3, Dec = -47.0 (J2000 degrees, equivalent to J2000 22h 29m, -47d 00'), with a statistical uncertainty of 1.5 degrees. The angle from the Fermi LAT boresight is 65.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210524208/quicklook/glg_skymap_all_bn210524208.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/bn210524208/quicklook/glg_healpix_all_bn210524208.fit The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210524208/quicklook/glg_lc_medres34_bn210524208.gif //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30072 SUBJECT: Fermi GRB 210524A: Global MASTER-Net observations report DATE: 21/05/24 05:32:00 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 210524A ( Fermi GBM team, GCN 30071) errorbox 559 sec after notice time and 597 sec after trigger time at 2021-05-24 05:09:56 UT, with upper limit up to 17.0 mag. Observations started at twilight. The observations began at zenith distance = 81 deg. The sun altitude is -12.3 deg. The galactic latitude b = -56 deg., longitude l = 348 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1620119 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 657 | 2021-05-24 05:09:56 | MASTER-IAC | (22h 28m 27.06s , -47d 09m 06.7s) | P| | 120 | 16.8 | 657 | 2021-05-24 05:09:56 | MASTER-IAC | (22h 27m 16.27s , -47d 03m 27.4s) | P- | 120 | 16.4 | 812 | 2021-05-24 05:12:16 | MASTER-IAC | (22h 28m 21.78s , -47d 10m 15.3s) | P| | 150 | 17.0 | 812 | 2021-05-24 05:12:16 | MASTER-IAC | (22h 27m 11.27s , -47d 04m 34.4s) | P- | 150 | 16.6 | 997 | 2021-05-24 05:15:06 | MASTER-IAC | (22h 28m 27.57s , -47d 09m 54.6s) | P| | 180 | 16.9 | 997 | 2021-05-24 05:15:06 | MASTER-IAC | (22h 27m 17.33s , -47d 04m 12.7s) | P- | 180 | 16.5 | 1197 | 2021-05-24 05:18:26 | MASTER-IAC | (22h 28m 24.64s , -47d 08m 43.0s) | P| | 180 | 16.7 | 1197 | 2021-05-24 05:18:26 | MASTER-IAC | (22h 27m 14.65s , -47d 03m 01.0s) | P- | 180 | 16.2 | 1397 | 2021-05-24 05:21:45 | MASTER-IAC | (22h 28m 24.73s , -47d 10m 02.6s) | P| | 180 | 16.4 | 1397 | 2021-05-24 05:21:45 | MASTER-IAC | (22h 27m 14.82s , -47d 04m 19.1s) | P- | 180 | 15.9 | The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30073 SUBJECT: GRB 210524A: BALROG localization (Fermi Trigger 643525204 / GRB 210524208) DATE: 21/05/24 10:13:22 GMT FROM: Jochen Greiner at MPE,Garching B. Biltzinger, F. Kunzweiler, F. Berlato, J. Burgess & J. Greiner (all MPE Garching) report: The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger 643525204 at 04:59:59 on 24 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) = 343.2+/-0.7 deg Decl.(2000.0) = -47.2+/-0.4 deg We estimate an additional systematic error of 2 deg. Further details are available at: https://grb.mpe.mpg.de/grb/GRB210524208/ The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB210524208/healpix The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB210524208/json //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30076 SUBJECT: IPN triangulation of GRB 210524A DATE: 21/05/25 10:03:18 GMT FROM: Dmitry Svinkin at Ioffe Institute K. Hurley, on behalf of the IPN, I. G. Mitrofanov, D. V. Golovin, A. S. Kozyrev, M. L. Litvak, and A. B. Sanin, on behalf of the HEND-Odyssey GRB team, D. Svinkin, S. Golenetskii, D. Frederiks, A. Ridnaia, A. Lysenko, and T. Cline on behalf of the Konus-Wind team, A. Goldstein, M. S. Briggs, and C. Wilson-Hodge on behalf of the Fermi GBM team, A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu on behalf of the Swift-BAT team, and W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on behalf of the GRS-Odyssey GRB team, report: The intense, long-duration GRB 210524A (Fermi-GBM detection: The Fermi GBM team, GCN Circ. 30071; BALROG localization: Biltzinger et al., GCN Circ. 30073) was detected by Fermi (GBM trigger 643525204), Konus-Wind, Mars-Odyssey (HEND), INTEGRAL (SPI-ACS), and Swift-BAT at about 17999 s UT (04:59:59). The burst was outside the coded field of view of the BAT. We have triangulated it to a preliminary, 3 sigma error box whose coordinates are: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 343.564 (22h 54m 15s) -46.672 (-46d 40' 19") Corners: 342.645 (22h 50m 35s) -49.867 (-49d 52' 00") 344.262 (22h 57m 03s) -43.354 (-43d 21' 13") 344.203 (22h 56m 49s) -43.132 (-43d 07' 56") 342.607 (22h 50m 26s) -49.680 (-49d 40' 48") --------------------------------------------- The error box area is 1584 sq. arcmin, and its maximum dimension is 6.8 deg (the minimum one is 4 arcmin). The Sun distance was 95 deg. This box may be improved. The IPN localization is consistent with, but reduces the area of, the Fermi RoboBA and BALROG localizations (GCN Circ. 30071 and 30073). A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB210524_T18010/IPN/ The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30077 SUBJECT: Konus-Wind detection of GRB 210524A DATE: 21/05/25 16:04:23 GMT FROM: Dmitry Svinkin at Ioffe Institute D. Svinkin, S. Golenetskii, D. Frederiks, M. Ulanov, A. Tsvetkova, A. Lysenko, A. Ridnaia, and T. Cline on behalf of the Konus-Wind team, report: The long-duration GRB 210524A (Fermi-GBM detection: The Fermi GBM team, GCN Circ. 30071; IPN triangulation: Hurley et al., GCN Circ. 30076) triggered Konus-Wind at T0=18010.925 s UT (05:00:10.925). The burst light curve shows a multi-peaked structure which starts at ~T0-3.5 s and has a total duration of ~11.5 s. The emission is seen up to ~1 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB210524_T18010/ As observed by Konus-Wind, the burst had a fluence of 8.64(-0.52,+0.56)x10^-6 erg/cm2, and a 64-ms peak flux, measured from T0+2.752 s, of 3.76(-1.00,+1.00)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 2 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -1.33(-0.19,+0.20) and Ep = 99(-10,+11) keV (chi2 = 45/56 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.7 (chi2 = 45/55 dof). All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.