GCN Circular 36648

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-Amur robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Blagoveshchensk State Pedagogical University) started inspect of the Fermi GRB240609.56 (trigger No 739632045,23h 16m 38.40s , +58d 14m 24.0s, R=1) errorbox  101 sec after notice time and 134 sec after trigger time at 2024-06-09 13:22:54 UT, with upper limit up to  17.0 mag. Observations started at twilight.  The observations began at zenith distance = 62 deg. The sun  altitude  is -11.8 deg. 

The galactic latitude b = -2 deg., longitude l = 111 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2487085

We obtain a following upper limits.  

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

     150 | 2024-06-09 13:22:54 |         MASTER-Amur | (23h 15m 30.99s , +57d 46m 01.7s) |   C |    30 | 17.0 |        
     218 | 2024-06-09 13:23:58 |         MASTER-Amur | (23h 15m 06.53s , +58d 22m 27.7s) |  P\ |    40 | 15.2 |        
     297 | 2024-06-09 13:25:12 |         MASTER-Amur | (23h 14m 58.88s , +58d 21m 26.5s) |  P\ |    50 | 14.6 |        
     390 | 2024-06-09 13:26:35 |         MASTER-Amur | (23h 15m 04.44s , +58d 21m 31.0s) |  P\ |    70 | 15.0 |        
Filter C is a clear (unfiltred) band. 


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