TITLE: GCN CIRCULAR NUMBER: 28364 SUBJECT: Fermi GRB 200903C: Global MASTER-Net observations report DATE: 20/09/04 01:30:59 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-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 200903C ( Fermi GBM team, GCN 28361) errorbox 8291 sec after notice time and 8323 sec after trigger time at 2020-09-03 23:57:42 UT, with upper limit up to 17.9 mag. The observations began at zenith distance = 77 deg. The sun altitude is -21.6 deg. MASTER-Tavrida robotic telescope located in Russia (Lomonosov MSU, SAI Crimea astronomical station) started inspect of the Fermi GRB 200903C errorbox 11113 sec after notice time and 11145 sec after trigger time at 2020-09-04 00:44:44 UT, with upper limit up to 16.5 mag. The observations began at zenith distance = 51 deg. The sun altitude is -24.3 deg. The galactic latitude b = -65 deg., longitude l = 117 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1433346 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 8414 | 2020-09-03 23:57:42 | MASTER-OAFA | (23h 45m 43.67s , -12d 49m 48.0s) | C | 180 | 17.9 | 10209 | 2020-09-04 00:27:37 | MASTER-OAFA | (00h 02m 47.84s , -16d 48m 14.1s) | C | 180 | 17.1 | 11236 | 2020-09-04 00:44:44 | MASTER-Tavrida | (00h 44m 08.68s , -04d 02m 46.7s) | C | 180 | 15.4 | 11437 | 2020-09-04 00:48:05 | MASTER-Tavrida | (01h 00m 04.67s , -04d 03m 05.0s) | C | 180 | 14.9 | 11637 | 2020-09-04 00:51:25 | MASTER-Tavrida | (01h 08m 06.78s , -04d 01m 49.9s) | C | 180 | 15.4 | 11838 | 2020-09-04 00:54:46 | MASTER-Tavrida | (00h 44m 09.09s , -04d 04m 10.7s) | C | 180 | 16.5 | 12039 | 2020-09-04 00:58:07 | MASTER-Tavrida | (00h 52m 02.97s , -04d 04m 55.6s) | C | 180 | 16.3 | 12241 | 2020-09-04 01:01:29 | MASTER-Tavrida | (01h 08m 11.79s , -04d 03m 50.0s) | C | 180 | 15.7 | 12441 | 2020-09-04 01:04:50 | MASTER-Tavrida | (00h 44m 29.40s , -08d 05m 45.3s) | C | 180 | 15.8 | 12642 | 2020-09-04 01:08:10 | MASTER-Tavrida | (00h 52m 09.85s , -04d 03m 39.9s) | C | 180 | 15.9 | 13245 | 2020-09-04 01:18:13 | MASTER-Tavrida | (00h 52m 32.44s , -08d 06m 10.8s) | C | 180 | 15.2 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.