TITLE: GCN CIRCULAR NUMBER: 29928 SUBJECT: Fermi GRB 210503A: Global MASTER-Net observations report DATE: 21/05/03 20:30:21 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 210503A ( Fermi GBM team, GCN 29927) errorbox 553 sec after notice time and 580 sec after trigger time at 2021-05-03 19:43:49 UT, with upper limit up to 18.6 mag. The observations began at zenith distance = 65 deg. The sun altitude is -28.1 deg. The galactic latitude b = 9 deg., longitude l = 107 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1606239 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 640 | 2021-05-03 19:43:49 | MASTER-Kislovodsk | (22h 04m 41.61s , +65d 36m 00.0s) | C | 120 | 17.8 | 795 | 2021-05-03 19:43:49 | MASTER-Kislovodsk | (22h 04m 41.62s , +65d 36m 00.1s) | C | 430 | 18.2 | Coadd 641 | 2021-05-03 19:43:50 | MASTER-Kislovodsk | (21h 55m 16.11s , +66d 01m 20.5s) | C | 120 | 17.4 | 796 | 2021-05-03 19:43:50 | MASTER-Kislovodsk | (21h 55m 16.11s , +66d 01m 20.6s) | C | 430 | 17.9 | Coadd 791 | 2021-05-03 19:46:10 | MASTER-Kislovodsk | (21h 55m 13.86s , +66d 02m 59.4s) | C | 140 | 17.4 | 791 | 2021-05-03 19:46:10 | MASTER-Kislovodsk | (22h 04m 39.81s , +65d 37m 37.1s) | C | 140 | 17.6 | 966 | 2021-05-03 19:48:50 | MASTER-Kislovodsk | (21h 55m 14.30s , +66d 01m 26.2s) | C | 170 | 17.5 | 966 | 2021-05-03 19:48:50 | MASTER-Kislovodsk | (22h 04m 39.77s , +65d 36m 02.5s) | C | 170 | 17.6 | 1161 | 2021-05-03 19:52:00 | MASTER-Kislovodsk | (21h 55m 17.75s , +66d 02m 50.4s) | C | 180 | 16.9 | 1162 | 2021-05-03 19:52:00 | MASTER-Kislovodsk | (22h 04m 43.87s , +65d 37m 25.6s) | C | 180 | 17.0 | 2005 | 2021-05-03 20:07:04 | MASTER-Kislovodsk | (21h 37m 10.39s , +66d 01m 47.0s) | C | 60 | 17.8 | 2005 | 2021-05-03 20:07:04 | MASTER-Kislovodsk | (21h 47m 15.11s , +65d 35m 53.1s) | C | 60 | 18.1 | 2085 | 2021-05-03 20:08:24 | MASTER-Kislovodsk | (22h 02m 55.09s , +68d 00m 35.5s) | C | 60 | 17.3 | 2085 | 2021-05-03 20:08:24 | MASTER-Kislovodsk | (22h 13m 49.89s , +67d 34m 30.0s) | C | 60 | 17.6 | 2165 | 2021-05-03 20:09:44 | MASTER-Kislovodsk | (21h 52m 55.00s , +64d 01m 52.3s) | C | 60 | 17.6 | 2165 | 2021-05-03 20:09:44 | MASTER-Kislovodsk | (22h 02m 14.69s , +63d 36m 02.4s) | C | 60 | 17.9 | 2245 | 2021-05-03 20:11:04 | MASTER-Kislovodsk | (22h 16m 27.15s , +66d 00m 24.9s) | C | 60 | 17.5 | 2245 | 2021-05-03 20:11:04 | MASTER-Kislovodsk | (22h 26m 29.07s , +65d 34m 25.8s) | C | 60 | 17.7 | 2326 | 2021-05-03 20:12:25 | MASTER-Kislovodsk | (21h 20m 16.68s , +68d 00m 22.7s) | C | 60 | 17.7 | 2326 | 2021-05-03 20:12:25 | MASTER-Kislovodsk | (21h 31m 11.18s , +67d 34m 26.7s) | C | 60 | 18.2 | 2406 | 2021-05-03 20:13:45 | MASTER-Kislovodsk | (21h 48m 48.66s , +70d 00m 16.6s) | C | 60 | 17.9 | 2406 | 2021-05-03 20:13:45 | MASTER-Kislovodsk | (22h 00m 44.35s , +69d 34m 04.3s) | C | 60 | 18.4 | 2686 | 2021-05-03 20:18:25 | MASTER-Kislovodsk | (22h 38m 42.00s , +63d 34m 18.9s) | C | 60 | 18.0 | 2686 | 2021-05-03 20:18:25 | MASTER-Kislovodsk | (22h 29m 29.94s , +63d 59m 46.5s) | C | 60 | 17.6 | 2767 | 2021-05-03 20:19:46 | MASTER-Kislovodsk | (22h 08m 18.67s , +62d 01m 27.6s) | C | 60 | 17.7 | 2767 | 2021-05-03 20:19:46 | MASTER-Kislovodsk | (22h 16m 54.68s , +61d 36m 05.7s) | C | 60 | 18.2 | 2847 | 2021-05-03 20:21:06 | MASTER-Kislovodsk | (21h 16m 33.92s , +64d 01m 43.6s) | C | 60 | 18.1 | 2847 | 2021-05-03 20:21:06 | MASTER-Kislovodsk | (21h 25m 48.93s , +63d 36m 22.4s) | C | 60 | 18.6 | 2927 | 2021-05-03 20:22:26 | MASTER-Kislovodsk | (21h 47m 08.96s , +65d 36m 48.0s) | C | 60 | 18.5 | 2927 | 2021-05-03 20:22:26 | MASTER-Kislovodsk | (21h 37m 11.26s , +66d 02m 19.3s) | C | 60 | 18.0 | 3007 | 2021-05-03 20:23:46 | MASTER-Kislovodsk | (22h 03m 09.27s , +68d 00m 46.9s) | C | 60 | 17.7 | 3007 | 2021-05-03 20:23:46 | MASTER-Kislovodsk | (22h 13m 56.78s , +67d 35m 04.6s) | C | 60 | 18.2 | 3087 | 2021-05-03 20:25:06 | MASTER-Kislovodsk | (21h 53m 02.84s , +64d 00m 05.4s) | C | 60 | 17.9 | 3087 | 2021-05-03 20:25:06 | MASTER-Kislovodsk | (22h 02m 15.96s , +63d 34m 40.4s) | C | 60 | 18.3 | 3167 | 2021-05-03 20:26:26 | MASTER-Kislovodsk | (22h 26m 30.72s , +65d 34m 32.3s) | C | 60 | 18.2 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.