TITLE: GCN CIRCULAR NUMBER: 44637 SUBJECT: Fermi GRB 260516B: Global MASTER-Net observations report DATE: 26/05/16 05:31:19 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-OAGH robotic telescope [1] located in Mexico (OAGH National Institute for Astrophysics, Optics and Electronics) started inspect of the Fermi GRB 260516B ( Fermi GBM team, GCN 44636) errorbox 25 sec after notice time and 66 sec after trigger time at 2026-05-16 05:13:43 UT, with upper limit up to 20.0 mag. The observations began at zenith distance = 33 deg. The sun altitude is -31.9 deg. The galactic latitude b = 62 deg., longitude l = 185 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3317801 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 71 | 2026-05-16 05:13:43 | MASTER-OAGH | (10h 51m 27.92s , +35d 52m 25.3s) | C | 10 | 17.7 | 71 | 2026-05-16 05:13:43 | MASTER-OAGH | (10h 42m 00.53s , +36d 28m 21.0s) | C | 10 | 18.1 | 96 | 2026-05-16 05:14:03 | MASTER-OAGH | (10h 51m 34.28s , +35d 52m 45.8s) | C | 20 | 18.5 | 96 | 2026-05-16 05:14:03 | MASTER-OAGH | (10h 42m 07.12s , +36d 28m 41.3s) | C | 20 | 18.7 | 127 | 2026-05-16 05:14:33 | MASTER-OAGH | (10h 47m 53.89s , +37d 48m 21.6s) | C | 20 | 18.5 | 127 | 2026-05-16 05:14:33 | MASTER-OAGH | (10h 38m 11.43s , +38d 24m 12.2s) | C | 20 | 18.9 | 164 | 2026-05-16 05:15:05 | MASTER-OAGH | (10h 50m 08.55s , +31d 29m 37.4s) | C | 30 | 18.4 | 209 | 2026-05-16 05:15:05 | MASTER-OAGH | (10h 50m 08.53s , +31d 29m 37.5s) | C | 120 | 19.5 | Coadd 164 | 2026-05-16 05:15:05 | MASTER-OAGH | (10h 41m 11.47s , +32d 05m 27.5s) | C | 30 | 19.0 | 209 | 2026-05-16 05:15:05 | MASTER-OAGH | (10h 41m 11.47s , +32d 05m 27.7s) | C | 120 | 19.9 | Coadd 209 | 2026-05-16 05:15:45 | MASTER-OAGH | (10h 50m 12.93s , +31d 31m 17.3s) | C | 40 | 18.6 | 209 | 2026-05-16 05:15:45 | MASTER-OAGH | (10h 41m 15.84s , +32d 07m 06.8s) | C | 40 | 19.2 | 264 | 2026-05-16 05:16:36 | MASTER-OAGH | (10h 50m 05.67s , +31d 30m 35.8s) | C | 50 | 19.0 | 264 | 2026-05-16 05:16:36 | MASTER-OAGH | (10h 41m 08.74s , +32d 06m 25.1s) | C | 50 | 19.4 | 329 | 2026-05-16 05:17:36 | MASTER-OAGH | (10h 50m 05.11s , +31d 31m 37.8s) | C | 60 | 19.0 | 329 | 2026-05-16 05:17:36 | MASTER-OAGH | (10h 41m 08.14s , +32d 07m 26.7s) | C | 60 | 19.5 | 637 | 2026-05-16 05:22:14 | MASTER-OAGH | (10h 49m 47.37s , +36d 49m 59.5s) | C | 120 | 19.7 | 637 | 2026-05-16 05:22:14 | MASTER-OAGH | (10h 40m 14.19s , +37d 25m 42.5s) | C | 120 | 20.0 | 768 | 2026-05-16 05:24:24 | MASTER-OAGH | (10h 49m 47.37s , +36d 48m 29.8s) | C | 120 | 19.7 | 768 | 2026-05-16 05:24:24 | MASTER-OAGH | (10h 40m 14.62s , +37d 24m 14.1s) | C | 120 | 19.8 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/44637. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...