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GCN 45186: Fermi trigger No 806104130: Global MASTER-Net observations report

2026-07-18T22:31:13.890Z | rev 0 | event: Fermi trigger No 806104130
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),
M. Segura,  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  [1]  located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB260718.91 (trigger No 806104130,00h 29m 02.40s , -00d 33m 00.0s, R=11.89) errorbox  792 sec after notice time and 803 sec after trigger time at 2026-07-18 22:02:09 UT, with upper limit up to  17.1 mag. The observations began at zenith distance = 72 deg. The sun  altitude  is -75.6 deg. 

The galactic latitude b = -63 deg., longitude l = 112 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=3433519

We obtain a following upper limits.  

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

     834 | 2026-07-18 22:02:09 |         MASTER-SAAO | (23h 54m 05.72s , -03d 01m 04.2s) |   C |    60 | 15.0 |        
    1139 | 2026-07-18 22:07:14 |         MASTER-SAAO | (00h 09m 13.60s , -01d 06m 25.9s) |   C |    60 | 14.8 |        
    1244 | 2026-07-18 22:08:59 |         MASTER-SAAO | (00h 09m 20.07s , -01d 07m 24.0s) |   C |    60 | 14.8 |        
    1350 | 2026-07-18 22:10:46 |         MASTER-SAAO | (00h 09m 13.69s , -01d 06m 25.2s) |   C |    60 | 13.2 |        
    1459 | 2026-07-18 22:12:34 |         MASTER-SAAO | (00h 09m 19.04s , -01d 07m 06.4s) |   C |    60 | 15.4 |        
    1565 | 2026-07-18 22:14:20 |         MASTER-SAAO | (00h 09m 12.41s , -01d 06m 25.3s) |   C |    60 | 15.6 |        
    1666 | 2026-07-18 22:16:01 |         MASTER-SAAO | (00h 24m 32.56s , -03d 01m 04.1s) |   C |    60 | 12.2 |        
    2184 | 2026-07-18 22:24:39 |         MASTER-SAAO | (00h 09m 13.55s , -03d 00m 26.1s) |   C |    60 | 16.4 |        
    2282 | 2026-07-18 22:26:17 |         MASTER-SAAO | (00h 09m 15.33s , -04d 55m 25.9s) |   C |    60 | 17.1 |        
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