TITLE: GCN CIRCULAR NUMBER: 29815 SUBJECT: Fermi GRB 210415A: Global MASTER-Net observations report DATE: 21/04/15 07:15:08 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 210415A ( Fermi GBM team, GCN 29814) errorbox 183 sec after notice time and 216 sec after trigger time at 2021-04-15 06:51:56 UT, with upper limit up to 17.9 mag. The observations began at zenith distance = 80 deg. The sun altitude is -51.8 deg. The galactic latitude b = 3 deg., longitude l = 259 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1592946 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 246 | 2021-04-15 06:51:56 | MASTER-OAFA | (09h 07m 34.52s , -35d 14m 21.0s) | C | 60 | 17.6 | 326 | 2021-04-15 06:53:15 | MASTER-OAFA | (09h 13m 34.85s , -33d 14m 59.7s) | C | 60 | 17.6 | 405 | 2021-04-15 06:54:35 | MASTER-OAFA | (09h 01m 52.73s , -37d 14m 56.7s) | C | 60 | 17.5 | 485 | 2021-04-15 06:55:54 | MASTER-OAFA | (09h 19m 53.44s , -31d 14m 12.4s) | C | 60 | 17.7 | 564 | 2021-04-15 06:57:14 | MASTER-OAFA | (08h 56m 37.35s , -39d 14m 03.0s) | C | 60 | 17.6 | 644 | 2021-04-15 06:58:34 | MASTER-OAFA | (09h 22m 12.49s , -37d 14m 26.1s) | C | 60 | 17.7 | 724 | 2021-04-15 06:59:53 | MASTER-OAFA | (09h 27m 17.12s , -35d 14m 49.3s) | C | 60 | 17.7 | 803 | 2021-04-15 07:01:12 | MASTER-OAFA | (08h 51m 35.77s , -41d 13m 57.9s) | C | 60 | 17.9 | 882 | 2021-04-15 07:02:32 | MASTER-OAFA | (08h 47m 08.04s , -43d 13m 58.0s) | C | 60 | 17.9 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.