GCN Circular 36926

V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik,  D. Vlasenko,
G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra
(The Instituto de Astrofisica de Canarias),

D. Buckley
(South African Astronomical Observatory),

O.A. Gress, N.M. Budnev, O.Ershova
(Irkutsk State University, API),

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

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

V. Yurkov, A. Gabovich
(Blagoveschensk Educational State University)

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 GRB240723.38 (trigger No 743418632,09h 02m 28.08s , +02d 19m 01.2s, R=36.23) errorbox  27246 sec after notice time and 27281 sec after trigger time at 2024-07-23 16:45:08 UT, with upper limit up to  18.0 mag. Observations started at twilight.  The observations began at zenith distance = 52 deg. The sun  altitude  is -10.4 deg. 

The galactic latitude b = 30 deg., longitude l = 228 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2538802

We obtain a following upper limits.  

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

   27311 | 2024-07-23 16:45:08 |         MASTER-SAAO | (11h 28m 21.09s , +03d 06m 47.8s) |   C |    60 | 17.0 |        
   27590 | 2024-07-23 16:49:47 |         MASTER-SAAO | (11h 20m 20.35s , +03d 07m 15.5s) |   C |    60 | 17.7 |        
   27670 | 2024-07-23 16:51:07 |         MASTER-SAAO | (11h 28m 15.58s , +03d 06m 12.9s) |   C |    60 | 18.0 |        
   28577 | 2024-07-23 17:05:14 |         MASTER-SAAO | (09h 25m 23.76s , -11d 27m 13.0s) |   C |   180 | 16.9 |        
Filter C is a clear (unfiltred) band. 


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