GCN Circular 36453

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 GRB240513.09 (trigger No 737258655,11h 24m 04.80s , -44d 18m 36.0s, R=6.1) errorbox  969 sec after notice time and 1026 sec after trigger time at 2024-05-13 02:21:16 UT, with upper limit up to  17.7 mag. The observations began at zenith distance = 81 deg. The sun  altitude  is -37.6 deg. 

The galactic latitude b = 16 deg., longitude l = 287 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2454134

We obtain a following upper limits.  

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

    1056 | 2024-05-13 02:21:16 |         MASTER-SAAO | (11h 20m 46.24s , -49d 57m 42.4s) |   C |    60 | 17.5 |        
    1056 | 2024-05-13 02:21:16 |         MASTER-SAAO | (11h 17m 56.14s , -49d 44m 08.6s) |   C |    60 | 17.0 |        
    1136 | 2024-05-13 02:22:36 |         MASTER-SAAO | (11h 33m 16.23s , -49d 58m 43.1s) |   C |    60 | 17.6 |        
    1136 | 2024-05-13 02:22:36 |         MASTER-SAAO | (11h 30m 26.14s , -49d 45m 10.4s) |   C |    60 | 17.3 |        
    1437 | 2024-05-13 02:27:37 |         MASTER-SAAO | (11h 57m 16.97s , -44d 16m 10.7s) |   C |    60 | 17.6 |        
    1437 | 2024-05-13 02:27:37 |         MASTER-SAAO | (11h 54m 43.94s , -44d 02m 38.5s) |   C |    60 | 16.9 |        
    1517 | 2024-05-13 02:28:57 |         MASTER-SAAO | (12h 08m 25.43s , -44d 17m 28.2s) |   C |    60 | 17.7 |        
    1517 | 2024-05-13 02:28:57 |         MASTER-SAAO | (12h 05m 52.41s , -44d 03m 56.5s) |   C |    60 | 17.3 |        
Filter C is a clear (unfiltred) band. 


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