//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30671 SUBJECT: GRB 210821A: Fermi GBM Final Real-time Localization DATE: 21/08/21 07:51:40 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM The Fermi GBM team reports the detection of a likely LONG GRB At 07:40:28 UT on 21 Aug 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210821A (trigger 651224433.594692 / 210821320). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 49.3, Dec = -6.9 (J2000 degrees, equivalent to J2000 03h 17m, -6d 54'), with a statistical uncertainty of 2.0 degrees. The angle from the Fermi LAT boresight is 87.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210821320/quicklook/glg_skymap_all_bn210821320.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/bn210821320/quicklook/glg_healpix_all_bn210821320.fit The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210821320/quicklook/glg_lc_medres34_bn210821320.gif //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30676 SUBJECT: Fermi GRB 210821A: Global MASTER-Net observations report DATE: 21/08/21 23:19:57 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-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 210821A ( Fermi GBM team, GCN 30671) errorbox 50201 sec after notice time and 50230 sec after trigger time at 2021-08-21 21:37:39 UT, with upper limit up to 12.6 mag. The observations began at zenith distance = 80 deg. The sun altitude is -34.8 deg. MASTER-Tavrida robotic telescope located in Russia (Lomonosov MSU, SAI Crimea astronomical station) started inspect of the Fermi GRB 210821A errorbox 54267 sec after notice time and 54295 sec after trigger time at 2021-08-21 22:45:24 UT, with upper limit up to 16.8 mag. The observations began at zenith distance = 76 deg. The sun altitude is -32.5 deg. The galactic latitude b = -49 deg., longitude l = 190 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1696282 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 50261 | 2021-08-21 21:37:39 | MASTER-Kislovodsk | (03h 06m 09.35s , -06d 43m 00.6s) | C | 60 | 12.0 | 50421 | 2021-08-21 21:40:19 | MASTER-Kislovodsk | (03h 05m 37.89s , -04d 47m 03.2s) | C | 60 | 12.6 | 50742 | 2021-08-21 21:45:40 | MASTER-Kislovodsk | (03h 06m 55.76s , -08d 34m 58.7s) | C | 60 | 12.6 | 54326 | 2021-08-21 22:45:24 | MASTER-Tavrida | (03h 20m 05.86s , -06d 10m 34.8s) | C | 60 | 16.2 | 54815 | 2021-08-21 22:53:33 | MASTER-Tavrida | (03h 12m 55.02s , -08d 06m 16.1s) | C | 60 | 16.3 | 55229 | 2021-08-21 23:00:27 | MASTER-Tavrida | (03h 21m 00.76s , -08d 04m 15.3s) | C | 60 | 16.3 | 55410 | 2021-08-21 23:03:28 | MASTER-Tavrida | (03h 12m 06.09s , -06d 12m 19.0s) | C | 60 | 16.8 | 55661 | 2021-08-21 23:07:39 | MASTER-Tavrida | (03h 20m 05.24s , -06d 10m 15.9s) | C | 60 | 16.6 | 56075 | 2021-08-21 23:14:33 | MASTER-Tavrida | (03h 12m 54.77s , -08d 04m 12.7s) | C | 60 | 16.8 | 56154 | 2021-08-21 23:15:52 | MASTER-Tavrida | (03h 21m 06.28s , -08d 05m 06.5s) | C | 60 | 16.5 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.