GCN Circular 36438

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 GRB240512.10 (trigger No 737173236,11h 08m 40.08s , -43d 19m 01.2s, R=4.88) errorbox  98 sec after notice time and 132 sec after trigger time at 2024-05-12 02:22:43 UT, with upper limit up to  17.2 mag. The observations began at zenith distance = 85 deg. The sun  altitude  is -37.2 deg. 

The galactic latitude b = 16 deg., longitude l = 284 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2452952

We obtain a following upper limits.  

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

     147 | 2024-05-12 02:22:43 |         MASTER-SAAO | (11h 09m 01.06s , -44d 37m 43.1s) |   C |    30 | 16.7 |        
     182 | 2024-05-12 02:22:43 |         MASTER-SAAO | (11h 09m 01.11s , -44d 37m 43.4s) |   C |   100 | 17.2 |  Coadd 
     197 | 2024-05-12 02:23:32 |         MASTER-SAAO | (11h 09m 00.97s , -44d 37m 38.6s) |   C |    30 | 16.7 |        
     251 | 2024-05-12 02:24:21 |         MASTER-SAAO | (11h 09m 00.69s , -44d 37m 32.1s) |   C |    40 | 16.8 |        
     315 | 2024-05-12 02:25:21 |         MASTER-SAAO | (11h 09m 00.39s , -44d 37m 26.1s) |   C |    50 | 16.8 |        
     390 | 2024-05-12 02:26:30 |         MASTER-SAAO | (11h 08m 60.00s , -44d 37m 18.4s) |   C |    60 | 16.8 |        
     808 | 2024-05-12 02:33:29 |         MASTER-SAAO | (11h 37m 51.72s , -47d 51m 01.6s) |   C |    60 | 17.0 |        
Filter C is a clear (unfiltred) band. 


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