GCN Circular 38475

V.Lipunov, E.Gorbovskoy, N.Tiurina,  P.Balanutsa, , D.Vlasenko, I.Panchenko,
A.Kuznetsov,  G.Antipov,  A.Sankovich, A.Sosnovskij, Yu.Tselik, M.Gulyaev, Ya.Kechin,
V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU),
O.Gress, N.Budnev (ISU),
C.Francile,  F. Podesta, R.Podesta, E. Gonzalez  (Observatorio Astronomico Felix Aguilar (OAFA),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity)
D.Buckley (SAAO),
R.Rebolo (The Instituto de Astrofisica de Canarias),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) 

MASTER-OAFA robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Argentina (OAFA observatory of San Juan National University) was pointed to the Swift GRB241209.23 (trigger No 1273071,10h 21m 30.24s , +06d 18m 57.6s, R=0.05) errorbox  38 sec after notice time and 236 sec after trigger time at 2024-12-09 05:39:40 UT, with upper limit up to  19.2 mag. The observations began at zenith distance = 69 deg. The sun  altitude  is -33.4 deg. 

The galactic latitude b = 49 deg., longitude l = 237 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2701042

We obtain a following upper limits.  

Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

     261 |         MASTER-OAFA |   C |    50 | 19.3 |        
Filter C is a clear (unfiltred) band. 


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