GCN Circular 45532

Subject
Fermi trigger No 810554827: Global MASTER-Net observations report
Date
2026-09-08T19:30:49Z (7 days ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
D.Buckley (SAAO),

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 (Lomonosov MSU)

A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity)
A.Sosnovskij (CrAO RAS)

A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory)

L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory)

R.Rebolo (The Instituto de Astrofisica de Canarias)

O.Gress, N.Budnev(ISU)

M. Segura,  F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA)


MASTER-SAAO robotic telescope  [1]  located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB260908.42 (trigger No 810554827,18h 50m 00.00s , -27d 54m 00.0s, R=28.3) errorbox  25158 sec after notice time and 25181 sec after trigger time at 2026-09-08 17:06:44 UT, with upper limit up to  18.2 mag. Observations started at twilight.  The observations began at zenith distance = 12 deg. The sun  altitude  is -10.1 deg. 

The galactic latitude b = -13 deg., longitude l =  8 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=3500765

We obtain a following upper limits.  

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

   25212 | 2026-09-08 17:06:44 |         MASTER-SAAO | (17h 46m 35.73s , -20d 28m 36.2s) |   C |    60 | 16.7 |        
   25305 | 2026-09-08 17:08:17 |         MASTER-SAAO | (17h 46m 29.61s , -20d 29m 33.0s) |   C |    60 | 16.2 |        
   25397 | 2026-09-08 17:09:49 |         MASTER-SAAO | (17h 46m 37.21s , -20d 29m 28.7s) |   C |    60 | 17.4 |        
   25491 | 2026-09-08 17:11:23 |         MASTER-SAAO | (17h 46m 33.34s , -20d 27m 55.5s) |   C |    60 | 16.6 |        
   25584 | 2026-09-08 17:12:56 |         MASTER-SAAO | (17h 46m 33.31s , -20d 28m 59.6s) |   C |    60 | 17.7 |        
   25677 | 2026-09-08 17:14:29 |         MASTER-SAAO | (17h 46m 36.62s , -20d 27m 38.3s) |   C |    60 | 17.9 |        
   25771 | 2026-09-08 17:16:03 |         MASTER-SAAO | (17h 46m 30.89s , -20d 28m 20.2s) |   C |    60 | 17.9 |        
   25865 | 2026-09-08 17:17:37 |         MASTER-SAAO | (17h 46m 29.51s , -20d 27m 17.9s) |   C |    60 | 18.0 |        
   26146 | 2026-09-08 17:22:18 |         MASTER-SAAO | (17h 46m 36.44s , -20d 28m 57.2s) |   C |    60 | 18.2 |        
   26801 | 2026-09-08 17:33:13 |         MASTER-SAAO | (17h 46m 31.17s , -20d 28m 52.8s) |   C |    60 | 18.2 |        
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