GCN Circular 36632

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 GRB240606.56 (trigger No 739373591,02h 38m 52.08s , -50d 19m 58.8s, R=7.75) errorbox  46650 sec after notice time and 46655 sec after trigger time at 2024-06-07 02:30:42 UT, with upper limit up to  19.4 mag. The observations began at zenith distance = 63 deg. The sun  altitude  is -38.0 deg. 

The galactic latitude b = -59 deg., longitude l = 268 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2484273

We obtain a following upper limits.  

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

   46686 | 2024-06-07 02:30:42 |         MASTER-SAAO | (02h 35m 58.12s , -50d 10m 57.8s) |   C |    60 | 19.4 |        
   46766 | 2024-06-07 02:32:01 |         MASTER-SAAO | (02h 48m 23.06s , -50d 11m 30.8s) |   C |    60 | 19.1 |        
   46845 | 2024-06-07 02:33:21 |         MASTER-SAAO | (02h 17m 46.96s , -52d 04m 39.7s) |   C |    60 | 18.6 |        
   46925 | 2024-06-07 02:34:41 |         MASTER-SAAO | (02h 30m 50.20s , -52d 06m 10.5s) |   C |    60 | 17.4 |        
   47005 | 2024-06-07 02:36:01 |         MASTER-SAAO | (02h 29m 52.03s , -48d 17m 19.9s) |   C |    60 | 18.7 |        
   47085 | 2024-06-07 02:37:20 |         MASTER-SAAO | (02h 41m 54.38s , -48d 15m 54.7s) |   C |    60 | 18.1 |        
   47165 | 2024-06-07 02:38:40 |         MASTER-SAAO | (02h 42m 31.89s , -52d 05m 50.6s) |   C |    60 | 16.6 |        
   47244 | 2024-06-07 02:40:00 |         MASTER-SAAO | (02h 55m 41.38s , -52d 05m 13.7s) |   C |    60 | 16.1 |        
   47324 | 2024-06-07 02:41:20 |         MASTER-SAAO | (02h 12m 05.06s , -50d 12m 35.9s) |   C |    60 | 13.7 |        
   48084 | 2024-06-07 02:53:59 |         MASTER-SAAO | (02h 35m 55.40s , -50d 11m 22.5s) |   C |    60 | 13.0 |        
   48163 | 2024-06-07 02:55:19 |         MASTER-SAAO | (02h 48m 21.03s , -50d 11m 56.1s) |   C |    60 | 15.4 |        
   48243 | 2024-06-07 02:56:39 |         MASTER-SAAO | (02h 17m 46.02s , -52d 06m 39.8s) |   C |    60 | 14.5 |        
Filter C is a clear (unfiltred) band. 


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