TITLE: GCN CIRCULAR NUMBER: 41569 SUBJECT: Fermi GRB 250827A: Global MASTER-Net observations report DATE: 25/08/27 18:31:07 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 GRB 250827A ( Fermi GBM team, GCN 41565) errorbox 4990 sec after notice time and 5027 sec after trigger time at 2025-08-27 16:58:40 UT, with upper limit up to 18.5 mag. Observations started at twilight. The observations began at zenith distance = 70 deg. The sun altitude is -9.1 deg. The galactic latitude b = -64 deg., longitude l = 348 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2978193 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 5057 | 2025-08-27 16:58:40 | MASTER-SAAO | (22h 53m 00.45s , -44d 30m 29.7s) | C | 60 | 15.0 | 5149 | 2025-08-27 17:00:12 | MASTER-SAAO | (23h 04m 08.41s , -44d 31m 25.0s) | C | 60 | 15.0 | 5247 | 2025-08-27 17:01:50 | MASTER-SAAO | (22h 51m 38.64s , -42d 35m 50.8s) | C | 60 | 15.4 | 5339 | 2025-08-27 17:03:22 | MASTER-SAAO | (23h 02m 31.98s , -42d 37m 28.4s) | C | 60 | 15.8 | 5430 | 2025-08-27 17:04:53 | MASTER-SAAO | (22h 55m 53.26s , -46d 24m 26.9s) | C | 60 | 16.1 | 5522 | 2025-08-27 17:06:25 | MASTER-SAAO | (23h 07m 29.25s , -46d 23m 23.1s) | C | 60 | 16.1 | 5615 | 2025-08-27 17:07:58 | MASTER-SAAO | (23h 12m 16.06s , -42d 37m 26.7s) | C | 60 | 16.2 | 5707 | 2025-08-27 17:09:30 | MASTER-SAAO | (23h 23m 15.11s , -42d 37m 12.2s) | C | 60 | 16.5 | 5800 | 2025-08-27 17:11:03 | MASTER-SAAO | (22h 52m 56.79s , -44d 29m 35.0s) | C | 60 | 16.9 | 5892 | 2025-08-27 17:12:35 | MASTER-SAAO | (23h 06m 32.59s , -44d 46m 11.8s) | C | 60 | 12.6 | 5892 | 2025-08-27 17:12:35 | MASTER-SAAO | (23h 04m 11.39s , -44d 31m 26.0s) | C | 60 | 16.9 | 5984 | 2025-08-27 17:14:07 | MASTER-SAAO | (22h 54m 00.36s , -42d 52m 10.3s) | C | 60 | 12.9 | 5984 | 2025-08-27 17:14:07 | MASTER-SAAO | (22h 51m 40.13s , -42d 36m 08.1s) | C | 60 | 17.4 | 6076 | 2025-08-27 17:15:38 | MASTER-SAAO | (23h 04m 49.74s , -42d 51m 47.2s) | C | 60 | 12.8 | 6076 | 2025-08-27 17:15:38 | MASTER-SAAO | (23h 02m 27.51s , -42d 36m 37.5s) | C | 60 | 17.5 | 6168 | 2025-08-27 17:17:11 | MASTER-SAAO | (22h 58m 24.36s , -46d 38m 32.3s) | C | 60 | 12.5 | 6168 | 2025-08-27 17:17:11 | MASTER-SAAO | (22h 55m 51.24s , -46d 23m 36.1s) | C | 60 | 17.5 | 6260 | 2025-08-27 17:18:43 | MASTER-SAAO | (23h 10m 04.21s , -46d 40m 47.6s) | C | 60 | 12.7 | 6260 | 2025-08-27 17:18:43 | MASTER-SAAO | (23h 07m 33.75s , -46d 24m 34.4s) | C | 60 | 17.7 | 6352 | 2025-08-27 17:20:15 | MASTER-SAAO | (23h 14m 34.57s , -42d 53m 42.5s) | C | 60 | 12.6 | 6352 | 2025-08-27 17:20:15 | MASTER-SAAO | (23h 12m 15.38s , -42d 37m 38.2s) | C | 60 | 17.8 | 6444 | 2025-08-27 17:21:47 | MASTER-SAAO | (23h 23m 15.76s , -42d 37m 11.0s) | C | 60 | 17.6 | 6537 | 2025-08-27 17:23:20 | MASTER-SAAO | (22h 55m 23.42s , -44d 45m 07.7s) | C | 60 | 12.2 | 6537 | 2025-08-27 17:23:20 | MASTER-SAAO | (22h 52m 55.38s , -44d 30m 04.0s) | C | 60 | 18.0 | 6629 | 2025-08-27 17:24:52 | MASTER-SAAO | (23h 06m 30.14s , -44d 47m 09.0s) | C | 60 | 12.7 | 6629 | 2025-08-27 17:24:52 | MASTER-SAAO | (23h 04m 10.07s , -44d 31m 34.5s) | C | 60 | 18.1 | 6721 | 2025-08-27 17:26:23 | MASTER-SAAO | (22h 54m 01.38s , -42d 52m 37.3s) | C | 60 | 12.6 | 6721 | 2025-08-27 17:26:23 | MASTER-SAAO | (22h 51m 39.24s , -42d 36m 10.8s) | C | 60 | 18.1 | 6812 | 2025-08-27 17:27:55 | MASTER-SAAO | (23h 04m 45.97s , -42d 51m 08.1s) | C | 60 | 12.8 | 6812 | 2025-08-27 17:27:55 | MASTER-SAAO | (23h 02m 26.80s , -42d 36m 48.6s) | C | 60 | 17.8 | 6903 | 2025-08-27 17:29:26 | MASTER-SAAO | (22h 58m 24.48s , -46d 39m 04.3s) | C | 60 | 12.2 | 6903 | 2025-08-27 17:29:26 | MASTER-SAAO | (22h 55m 50.57s , -46d 23m 47.2s) | C | 60 | 18.1 | 6995 | 2025-08-27 17:30:57 | MASTER-SAAO | (23h 10m 03.97s , -46d 40m 48.6s) | C | 60 | 13.3 | 6995 | 2025-08-27 17:30:57 | MASTER-SAAO | (23h 07m 33.26s , -46d 24m 46.2s) | C | 60 | 18.2 | 7087 | 2025-08-27 17:32:30 | MASTER-SAAO | (23h 14m 34.41s , -42d 52m 08.5s) | C | 60 | 12.6 | 7087 | 2025-08-27 17:32:30 | MASTER-SAAO | (23h 12m 15.32s , -42d 37m 50.3s) | C | 60 | 18.2 | 7179 | 2025-08-27 17:34:02 | MASTER-SAAO | (23h 25m 37.26s , -42d 52m 57.4s) | C | 60 | 12.9 | 7179 | 2025-08-27 17:34:02 | MASTER-SAAO | (23h 23m 14.32s , -42d 37m 20.3s) | C | 60 | 18.1 | 7272 | 2025-08-27 17:35:34 | MASTER-SAAO | (22h 55m 22.47s , -44d 45m 30.3s) | C | 60 | 13.1 | 7272 | 2025-08-27 17:35:34 | MASTER-SAAO | (22h 52m 54.03s , -44d 30m 06.0s) | C | 60 | 18.3 | 7363 | 2025-08-27 17:37:06 | MASTER-SAAO | (23h 06m 33.59s , -44d 47m 46.3s) | C | 60 | 12.7 | 7363 | 2025-08-27 17:37:06 | MASTER-SAAO | (23h 04m 08.73s , -44d 31m 42.3s) | C | 60 | 18.2 | 7455 | 2025-08-27 17:38:38 | MASTER-SAAO | (22h 53m 58.35s , -42d 52m 13.3s) | C | 60 | 13.4 | 7455 | 2025-08-27 17:38:38 | MASTER-SAAO | (22h 51m 38.67s , -42d 36m 07.8s) | C | 60 | 18.1 | 7547 | 2025-08-27 17:40:10 | MASTER-SAAO | (23h 04m 46.10s , -42d 51m 19.6s) | C | 60 | 12.6 | 7547 | 2025-08-27 17:40:10 | MASTER-SAAO | (23h 02m 26.49s , -42d 37m 00.5s) | C | 60 | 18.3 | 7639 | 2025-08-27 17:41:41 | MASTER-SAAO | (22h 58m 23.04s , -46d 39m 30.5s) | C | 60 | 13.5 | 7639 | 2025-08-27 17:41:41 | MASTER-SAAO | (22h 55m 49.37s , -46d 23m 58.8s) | C | 60 | 18.2 | 7730 | 2025-08-27 17:43:13 | MASTER-SAAO | (23h 10m 04.09s , -46d 40m 59.5s) | C | 60 | 13.3 | 7730 | 2025-08-27 17:43:13 | MASTER-SAAO | (23h 07m 32.57s , -46d 24m 58.3s) | C | 60 | 18.3 | 7822 | 2025-08-27 17:44:45 | MASTER-SAAO | (23h 14m 34.23s , -42d 54m 05.7s) | C | 60 | 12.9 | 7822 | 2025-08-27 17:44:45 | MASTER-SAAO | (23h 12m 13.06s , -42d 38m 02.3s) | C | 60 | 18.2 | 7914 | 2025-08-27 17:46:17 | MASTER-SAAO | (23h 25m 31.77s , -42d 53m 59.7s) | C | 60 | 12.9 | 7914 | 2025-08-27 17:46:17 | MASTER-SAAO | (23h 23m 11.95s , -42d 37m 54.5s) | C | 60 | 18.3 | 8006 | 2025-08-27 17:47:49 | MASTER-SAAO | (22h 52m 52.65s , -44d 30m 26.9s) | C | 60 | 18.3 | 8098 | 2025-08-27 17:49:21 | MASTER-SAAO | (23h 06m 35.89s , -44d 46m 34.9s) | C | 60 | 12.2 | 8098 | 2025-08-27 17:49:21 | MASTER-SAAO | (23h 04m 07.29s , -44d 31m 42.8s) | C | 60 | 18.2 | 8190 | 2025-08-27 17:50:52 | MASTER-SAAO | (22h 51m 36.87s , -42d 36m 36.2s) | C | 60 | 18.4 | 8281 | 2025-08-27 17:52:24 | MASTER-SAAO | (23h 04m 47.02s , -42d 51m 31.9s) | C | 60 | 12.8 | 8281 | 2025-08-27 17:52:24 | MASTER-SAAO | (23h 02m 24.41s , -42d 37m 11.6s) | C | 60 | 18.1 | 8374 | 2025-08-27 17:53:56 | MASTER-SAAO | (22h 58m 21.84s , -46d 39m 43.1s) | C | 60 | 13.2 | 8374 | 2025-08-27 17:53:56 | MASTER-SAAO | (22h 55m 47.51s , -46d 24m 09.0s) | C | 60 | 18.1 | 8464 | 2025-08-27 17:55:27 | MASTER-SAAO | (23h 10m 03.50s , -46d 41m 10.1s) | C | 60 | 13.5 | 8464 | 2025-08-27 17:55:27 | MASTER-SAAO | (23h 07m 31.49s , -46d 25m 09.3s) | C | 60 | 18.3 | 8556 | 2025-08-27 17:56:59 | MASTER-SAAO | (23h 12m 12.36s , -42d 38m 13.7s) | C | 60 | 18.3 | 8648 | 2025-08-27 17:58:31 | MASTER-SAAO | (23h 25m 31.50s , -42d 54m 10.7s) | C | 60 | 13.3 | 8648 | 2025-08-27 17:58:31 | MASTER-SAAO | (23h 23m 11.42s , -42d 38m 05.6s) | C | 60 | 18.4 | 8741 | 2025-08-27 18:00:04 | MASTER-SAAO | (22h 55m 16.95s , -44d 44m 44.6s) | C | 60 | 12.4 | 8741 | 2025-08-27 18:00:04 | MASTER-SAAO | (22h 52m 51.29s , -44d 30m 30.5s) | C | 60 | 18.5 | 8840 | 2025-08-27 18:01:43 | MASTER-SAAO | (23h 06m 31.53s , -44d 48m 23.1s) | C | 60 | 12.8 | 8840 | 2025-08-27 18:01:43 | MASTER-SAAO | (23h 04m 06.06s , -44d 32m 15.8s) | C | 60 | 18.4 | 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/41569. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...