TITLE: GCN CIRCULAR NUMBER: 29922 SUBJECT: Fermi trigger No 641601187: Global MASTER-Net observations report DATE: 21/05/01 23:00:10 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 GRB210501.94 (trigger No 641601187,13h 03m 36.00s , +46d 15m 36.0s, R=7.58) errorbox 208 sec after notice time and 234 sec after trigger time at 2021-05-01 22:36:57 UT, with upper limit up to 19.0 mag. The observations began at zenith distance = 32 deg. The sun altitude is -28.2 deg. MASTER-Tavrida robotic telescope located in Russia (Lomonosov MSU, SAI Crimea astronomical station) started inspect of the Fermi GRB210501.94 errorbox 212 sec after notice time and 238 sec after trigger time at 2021-05-01 22:37:00 UT, with upper limit up to 18.7 mag. The observations began at zenith distance = 26 deg. The sun altitude is -29.3 deg. The galactic latitude b = 71 deg., longitude l = 115 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1605248 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 265 | 2021-05-01 22:36:57 | MASTER-Kislovodsk | (13h 03m 28.07s , +46d 00m 21.4s) | C | 60 | 18.2 | 265 | 2021-05-01 22:36:57 | MASTER-Kislovodsk | (12h 57m 17.97s , +46d 22m 52.9s) | C | 60 | 18.8 | 269 | 2021-05-01 22:37:00 | MASTER-Tavrida | (13h 04m 14.39s , +48d 03m 20.7s) | C | 60 | 18.3 | 345 | 2021-05-01 22:38:17 | MASTER-Kislovodsk | (12h 52m 53.92s , +44d 21m 14.1s) | C | 60 | 18.9 | 348 | 2021-05-01 22:38:20 | MASTER-Tavrida | (13h 16m 14.50s , +48d 04m 39.6s) | C | 60 | 18.6 | 425 | 2021-05-01 22:39:37 | MASTER-Kislovodsk | (12h 45m 32.47s , +47d 59m 53.1s) | C | 60 | 18.4 | 425 | 2021-05-01 22:39:37 | MASTER-Kislovodsk | (12h 39m 09.62s , +48d 22m 22.9s) | C | 60 | 19.0 | 428 | 2021-05-01 22:39:40 | MASTER-Tavrida | (13h 16m 12.56s , +44d 02m 30.2s) | C | 60 | 16.6 | 505 | 2021-05-01 22:40:57 | MASTER-Kislovodsk | (13h 26m 28.32s , +45d 59m 51.4s) | C | 60 | 18.1 | 505 | 2021-05-01 22:40:57 | MASTER-Kislovodsk | (13h 20m 15.06s , +46d 22m 25.2s) | C | 60 | 18.7 | 507 | 2021-05-01 22:40:59 | MASTER-Tavrida | (13h 27m 26.63s , +44d 02m 45.8s) | C | 60 | 18.5 | 586 | 2021-05-01 22:42:17 | MASTER-Kislovodsk | (12h 40m 21.77s , +46d 00m 09.3s) | C | 60 | 18.3 | 586 | 2021-05-01 22:42:17 | MASTER-Kislovodsk | (12h 34m 13.64s , +46d 22m 35.8s) | C | 60 | 18.9 | 587 | 2021-05-01 22:42:18 | MASTER-Tavrida | (13h 11m 35.39s , +50d 02m 40.9s) | C | 60 | 17.6 | 666 | 2021-05-01 22:43:38 | MASTER-Kislovodsk | (12h 52m 03.97s , +49d 59m 12.9s) | C | 60 | 18.3 | 666 | 2021-05-01 22:43:38 | MASTER-Kislovodsk | (12h 45m 23.32s , +50d 21m 38.9s) | C | 60 | 18.9 | 746 | 2021-05-01 22:44:58 | MASTER-Kislovodsk | (13h 33m 21.76s , +47d 58m 55.8s) | C | 60 | 18.1 | 746 | 2021-05-01 22:44:58 | MASTER-Kislovodsk | (13h 26m 52.82s , +48d 21m 29.3s) | C | 60 | 18.8 | 819 | 2021-05-01 22:46:11 | MASTER-Tavrida | (13h 24m 05.25s , +50d 04m 31.3s) | C | 60 | 18.7 | 826 | 2021-05-01 22:46:18 | MASTER-Kislovodsk | (12h 36m 37.69s , +43d 58m 26.2s) | C | 60 | 18.2 | 826 | 2021-05-01 22:46:18 | MASTER-Kislovodsk | (12h 30m 44.01s , +44d 20m 52.3s) | C | 60 | 18.8 | 899 | 2021-05-01 22:47:31 | MASTER-Tavrida | (13h 23m 09.72s , +42d 03m 15.8s) | C | 60 | 18.5 | 906 | 2021-05-01 22:47:37 | MASTER-Kislovodsk | (13h 00m 01.13s , +51d 59m 53.9s) | C | 60 | 18.3 | 906 | 2021-05-01 22:47:38 | MASTER-Kislovodsk | (12h 53m 00.96s , +52d 22m 15.5s) | C | 60 | 19.0 | 978 | 2021-05-01 22:48:50 | MASTER-Tavrida | (12h 48m 35.84s , +40d 01m 30.9s) | C | 60 | 18.2 | 1258 | 2021-05-01 22:53:30 | MASTER-Tavrida | (12h 58m 58.75s , +40d 01m 33.4s) | C | 60 | 18.6 | 1338 | 2021-05-01 22:54:49 | MASTER-Tavrida | (13h 04m 19.98s , +48d 03m 41.6s) | C | 60 | 18.7 | 1417 | 2021-05-01 22:56:09 | MASTER-Tavrida | (13h 16m 13.51s , +48d 03m 04.5s) | C | 60 | 18.5 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.