TITLE: GCN CIRCULAR NUMBER: 40096 SUBJECT: Fermi GRB 250406A: Global MASTER-Net observations report DATE: 25/04/06 18:15:59 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, N.Tiurina, P.Balanutsa, , D.Vlasenko, I.Panchenko, A.Kuznetsov, G.Antipov, A.Sankovich, A.Sosnovskij, Yu.Tselik, M.Gulyaev, 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. 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 250406A ( Fermi GBM team, GCN 40094) errorbox 9143 sec after notice time and 9171 sec after trigger time at 2025-04-06 17:11:03 UT, with upper limit up to 18.1 mag. Observations started at twilight. The observations began at zenith distance = 68 deg. The sun altitude is -9.9 deg. The galactic latitude b = -54 deg., longitude l = 308 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2834949 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 9202 | 2025-04-06 17:11:03 | MASTER-SAAO | (00h 25m 46.55s , -63d 33m 50.2s) | C | 60 | 16.6 | 9281 | 2025-04-06 17:12:22 | MASTER-SAAO | (00h 43m 35.96s , -63d 32m 39.4s) | C | 60 | 16.8 | 9360 | 2025-04-06 17:13:41 | MASTER-SAAO | (00h 24m 01.48s , -61d 38m 12.8s) | C | 60 | 16.8 | 9439 | 2025-04-06 17:15:01 | MASTER-SAAO | (00h 40m 43.37s , -61d 39m 07.2s) | C | 60 | 17.0 | 9519 | 2025-04-06 17:16:20 | MASTER-SAAO | (00h 27m 48.66s , -65d 26m 57.7s) | C | 60 | 17.2 | 9803 | 2025-04-06 17:21:04 | MASTER-SAAO | (00h 09m 41.55s , -63d 33m 51.5s) | C | 60 | 17.6 | 9889 | 2025-04-06 17:22:30 | MASTER-SAAO | (00h 25m 49.55s , -63d 32m 19.4s) | C | 60 | 17.7 | 10129 | 2025-04-06 17:26:30 | MASTER-SAAO | (00h 43m 41.72s , -63d 33m 01.9s) | C | 60 | 17.9 | 10209 | 2025-04-06 17:27:50 | MASTER-SAAO | (00h 23m 59.75s , -61d 39m 57.8s) | C | 60 | 17.7 | 10289 | 2025-04-06 17:29:10 | MASTER-SAAO | (00h 40m 51.41s , -61d 39m 35.0s) | C | 60 | 17.9 | 10368 | 2025-04-06 17:30:29 | MASTER-SAAO | (00h 27m 50.49s , -65d 25m 58.4s) | C | 60 | 17.8 | 10653 | 2025-04-06 17:35:14 | MASTER-SAAO | (00h 09m 43.11s , -63d 32m 50.4s) | C | 60 | 18.0 | 10733 | 2025-04-06 17:36:34 | MASTER-SAAO | (00h 25m 48.42s , -63d 31m 49.8s) | C | 60 | 17.9 | 10812 | 2025-04-06 17:37:53 | MASTER-SAAO | (00h 43m 45.24s , -63d 32m 51.2s) | C | 60 | 18.1 | 10892 | 2025-04-06 17:39:13 | MASTER-SAAO | (00h 24m 03.87s , -61d 39m 50.1s) | C | 60 | 17.9 | 10971 | 2025-04-06 17:40:32 | MASTER-SAAO | (00h 40m 54.53s , -61d 39m 38.8s) | C | 60 | 17.8 | 11051 | 2025-04-06 17:41:52 | MASTER-SAAO | (00h 27m 55.06s , -65d 25m 49.8s) | C | 60 | 17.8 | 11335 | 2025-04-06 17:46:36 | MASTER-SAAO | (00h 09m 48.00s , -63d 32m 47.3s) | C | 60 | 17.8 | 11415 | 2025-04-06 17:47:56 | MASTER-SAAO | (00h 25m 51.70s , -63d 31m 45.0s) | C | 60 | 17.9 | 11494 | 2025-04-06 17:49:15 | MASTER-SAAO | (00h 43m 49.94s , -63d 32m 44.3s) | C | 60 | 17.9 | 11574 | 2025-04-06 17:50:35 | MASTER-SAAO | (00h 24m 06.65s , -61d 39m 45.5s) | C | 60 | 17.9 | 11653 | 2025-04-06 17:51:54 | MASTER-SAAO | (00h 40m 58.05s , -61d 39m 30.5s) | C | 60 | 17.9 | 12144 | 2025-04-06 18:00:05 | MASTER-SAAO | (00h 28m 06.48s , -65d 25m 50.6s) | C | 60 | 17.9 | 12430 | 2025-04-06 18:04:52 | MASTER-SAAO | (00h 10m 03.09s , -63d 32m 45.1s) | C | 60 | 17.8 | 12510 | 2025-04-06 18:06:11 | MASTER-SAAO | (00h 25m 59.78s , -63d 33m 39.9s) | C | 60 | 17.8 | 12589 | 2025-04-06 18:07:30 | MASTER-SAAO | (00h 43m 57.06s , -63d 33m 07.7s) | C | 60 | 17.9 | 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/40096. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...