GCN Circular 36904

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) was pointed to the LAT GRB240718.27 (trigger No 742976945,16h 51m 07.20s , -25d 06m 00.0s, R=0.299833) errorbox  20292 sec after notice time and 42709 sec after trigger time at 2024-07-18 18:20:49 UT, with upper limit up to  15.5 mag. The observations began at zenith distance = 19 deg. The sun  altitude  is -30.7 deg. 

The galactic latitude b = 12 deg., longitude l = 357 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2534301

We obtain a following upper limits.  

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

   42725 | 2024-07-18 18:20:49 |         MASTER-SAAO | (16h 49m 33.00s , -25d 18m 29.3s) |   C |    30 | 15.2 |        
   42774 | 2024-07-18 18:21:38 |         MASTER-SAAO | (16h 49m 26.14s , -25d 19m 28.7s) |   C |    30 | 15.5 |        
   42824 | 2024-07-18 18:22:28 |         MASTER-SAAO | (16h 49m 33.34s , -25d 19m 11.5s) |   C |    30 | 15.4 |        
   42877 | 2024-07-18 18:23:22 |         MASTER-SAAO | (16h 49m 29.78s , -25d 17m 44.9s) |   C |    30 | 15.2 |        
   42927 | 2024-07-18 18:24:12 |         MASTER-SAAO | (16h 49m 29.74s , -25d 19m 18.0s) |   C |    30 | 15.3 |        
Filter C is a clear (unfiltred) band. 


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