TITLE: GCN CIRCULAR NUMBER: 29648 SUBJECT: Fermi GRB 210312A: Global MASTER-Net observations report DATE: 21/03/12 19:30:55 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-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 210312A ( Fermi GBM team, GCN 29646) errorbox 49542 sec after notice time and 49580 sec after trigger time at 2021-03-12 17:50:25 UT, with upper limit up to 20.1 mag. Observations started at twilight. The observations began at zenith distance = 33 deg. The sun altitude is -11.4 deg. MASTER-Kislovodsk robotic telescope located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 210312A errorbox 52229 sec after notice time and 52267 sec after trigger time at 2021-03-12 18:35:12 UT, with upper limit up to 18.3 mag. The observations began at zenith distance = 71 deg. The sun altitude is -35.8 deg. The galactic latitude b = -37 deg., longitude l = 213 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1566766 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 49610 | 2021-03-12 17:50:25 | MASTER-SAAO | (04h 22m 26.21s , -17d 08m 14.9s) | C | 60 | 18.7 | 49770 | 2021-03-12 17:53:04 | MASTER-SAAO | (04h 25m 15.76s , -19d 08m 04.1s) | C | 60 | 18.8 | 49849 | 2021-03-12 17:54:24 | MASTER-SAAO | (04h 39m 05.34s , -17d 07m 13.4s) | C | 60 | 19.0 | 49929 | 2021-03-12 17:55:44 | MASTER-SAAO | (04h 36m 36.02s , -15d 07m 09.6s) | C | 60 | 19.2 | 50089 | 2021-03-12 17:58:23 | MASTER-SAAO | (04h 19m 59.21s , -15d 06m 06.2s) | C | 60 | 19.0 | 50168 | 2021-03-12 17:59:43 | MASTER-SAAO | (04h 42m 08.63s , -19d 06m 29.9s) | C | 60 | 19.4 | 50254 | 2021-03-12 18:01:09 | MASTER-SAAO | (04h 28m 23.74s , -21d 05m 55.2s) | C | 60 | 19.4 | 50334 | 2021-03-12 18:02:28 | MASTER-SAAO | (04h 34m 14.90s , -13d 07m 55.1s) | C | 60 | 19.2 | 50414 | 2021-03-12 18:03:48 | MASTER-SAAO | (04h 17m 52.38s , -13d 06m 08.9s) | C | 60 | 19.2 | 50493 | 2021-03-12 18:05:08 | MASTER-SAAO | (04h 08m 24.35s , -19d 06m 02.3s) | C | 60 | 19.4 | 50573 | 2021-03-12 18:06:27 | MASTER-SAAO | (04h 22m 20.34s , -17d 06m 41.6s) | C | 60 | 19.3 | 50653 | 2021-03-12 18:07:47 | MASTER-SAAO | (04h 30m 41.15s , -17d 05m 41.5s) | C | 60 | 19.4 | 50733 | 2021-03-12 18:09:07 | MASTER-SAAO | (04h 25m 15.70s , -19d 06m 37.1s) | C | 60 | 19.5 | 50812 | 2021-03-12 18:10:27 | MASTER-SAAO | (04h 33m 36.32s , -19d 07m 37.3s) | C | 60 | 19.5 | 50892 | 2021-03-12 18:11:47 | MASTER-SAAO | (04h 45m 28.99s , -21d 05m 47.0s) | C | 60 | 19.6 | 50972 | 2021-03-12 18:13:06 | MASTER-SAAO | (04h 05m 43.83s , -17d 05m 49.0s) | C | 60 | 19.4 | 51052 | 2021-03-12 18:14:26 | MASTER-SAAO | (04h 11m 17.39s , -21d 05m 19.2s) | C | 60 | 19.4 | 51131 | 2021-03-12 18:15:46 | MASTER-SAAO | (04h 31m 58.67s , -23d 07m 24.2s) | C | 60 | 19.7 | 51371 | 2021-03-12 18:19:45 | MASTER-SAAO | (04h 39m 03.41s , -17d 07m 17.2s) | C | 60 | 19.6 | 51451 | 2021-03-12 18:21:05 | MASTER-SAAO | (04h 47m 27.90s , -17d 05m 38.3s) | C | 60 | 19.6 | 51530 | 2021-03-12 18:22:25 | MASTER-SAAO | (04h 36m 23.44s , -15d 06m 11.5s) | C | 60 | 19.6 | 51610 | 2021-03-12 18:23:45 | MASTER-SAAO | (04h 44m 40.21s , -15d 05m 10.5s) | C | 60 | 19.5 | 51690 | 2021-03-12 18:25:04 | MASTER-SAAO | (04h 19m 55.83s , -15d 05m 56.8s) | C | 60 | 19.5 | 51783 | 2021-03-12 18:26:38 | MASTER-SAAO | (04h 28m 05.21s , -15d 06m 57.2s) | C | 60 | 19.6 | 51863 | 2021-03-12 18:27:57 | MASTER-SAAO | (04h 42m 03.68s , -19d 06m 45.4s) | C | 60 | 19.8 | 51942 | 2021-03-12 18:29:17 | MASTER-SAAO | (04h 50m 27.68s , -19d 05m 28.1s) | C | 60 | 20.1 | 52022 | 2021-03-12 18:30:37 | MASTER-SAAO | (04h 28m 21.20s , -21d 06m 44.3s) | C | 60 | 19.6 | 52102 | 2021-03-12 18:31:56 | MASTER-SAAO | (04h 36m 55.61s , -21d 05m 02.1s) | C | 60 | 19.6 | 52181 | 2021-03-12 18:33:16 | MASTER-SAAO | (04h 34m 07.95s , -13d 05m 44.7s) | C | 60 | 19.4 | 52261 | 2021-03-12 18:34:36 | MASTER-SAAO | (04h 42m 19.44s , -13d 04m 45.1s) | C | 60 | 19.0 | 52297 | 2021-03-12 18:35:12 | MASTER-Kislovodsk | (05h 07m 39.65s , -08d 00m 12.7s) | C | 60 | 17.5 | 52297 | 2021-03-12 18:35:12 | MASTER-Kislovodsk | (05h 03m 51.59s , -07d 36m 33.1s) | C | 60 | 18.3 | 53353 | 2021-03-12 18:52:47 | MASTER-Kislovodsk | (05h 07m 38.52s , -08d 00m 53.3s) | C | 60 | 15.2 | 53353 | 2021-03-12 18:52:47 | MASTER-Kislovodsk | (05h 03m 51.06s , -07d 37m 50.0s) | C | 60 | 15.7 | 54362 | 2021-03-12 19:09:36 | MASTER-Kislovodsk | (05h 07m 38.90s , -08d 02m 01.0s) | C | 60 | 15.9 | 54362 | 2021-03-12 19:09:36 | MASTER-Kislovodsk | (05h 03m 53.22s , -07d 38m 45.8s) | C | 60 | 16.6 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.