TITLE: GCN CIRCULAR NUMBER: 41125 SUBJECT: Fermi trigger No 774730635: Global MASTER-Net observations report DATE: 25/07/20 22:16:48 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-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB250720.79 (trigger No 774730635,06h 08m 09.60s , -80d 39m 00.0s, R=5.52) errorbox 8747 sec after notice time and 8781 sec after trigger time at 2025-07-20 21:23:31 UT, with upper limit up to 19.7 mag. The observations began at zenith distance = 67 deg. The sun altitude is -68.5 deg.

The galactic latitude b = -29 deg., longitude l = 293 deg.

Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2942376

We obtain a following upper limits.

Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________

8811 | 2025-07-20 21:23:31 | MASTER-SAAO | (06h 02m 59.30s , -80d 27m 46.8s) | C | 60 | 18.8 | 8871 | 2025-07-20 21:23:31 | MASTER-SAAO | (06h 02m 59.34s , -80d 27m 46.6s) | C | 180 | 19.6 | Coadd 8811 | 2025-07-20 21:23:31 | MASTER-SAAO | (06h 13m 30.89s , -80d 42m 49.8s) | C | 60 | 18.8 | 8871 | 2025-07-20 21:23:31 | MASTER-SAAO | (06h 13m 30.90s , -80d 42m 49.8s) | C | 180 | 19.7 | Coadd 8891 | 2025-07-20 21:24:50 | MASTER-SAAO | (06h 02m 59.31s , -80d 27m 43.2s) | C | 60 | 19.0 | 8891 | 2025-07-20 21:24:50 | MASTER-SAAO | (06h 13m 30.67s , -80d 42m 46.5s) | C | 60 | 19.0 | 8970 | 2025-07-20 21:26:09 | MASTER-SAAO | (06h 02m 59.58s , -80d 27m 41.8s) | C | 60 | 19.0 | 8970 | 2025-07-20 21:26:09 | MASTER-SAAO | (06h 13m 30.80s , -80d 42m 44.5s) | C | 60 | 19.0 | 9048 | 2025-07-20 21:27:28 | MASTER-SAAO | (06h 02m 59.74s , -80d 27m 41.8s) | C | 60 | 18.9 | 9048 | 2025-07-20 21:27:28 | MASTER-SAAO | (06h 13m 30.95s , -80d 42m 43.7s) | C | 60 | 19.0 | Filter C is a clear (unfiltred) band.

The observation and reduction will continue. The message may be cited.

View this GCN Circular online at https://gcn.nasa.gov/circulars/41125. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...