GCN Circular 35315

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-Kislovodsk robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB231210.55 (trigger No 723906955,09h 11m 38.40s , +10d 20m 24.0s, R=14.38) errorbox  26943 sec after notice time and 27055 sec after trigger time at 2023-12-10 20:46:45 UT, with upper limit up to  19.6 mag. The observations began at zenith distance = 57 deg. The sun  altitude  is -69.6 deg. 

MASTER-SAAO robotic telescope  located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB231210.55 errorbox  29290 sec after notice time and 29401 sec after trigger time at 2023-12-10 21:25:51 UT, with upper limit up to  19.2 mag. The observations began at zenith distance = 79 deg. The sun  altitude  is -32.9 deg. 

The galactic latitude b = 36 deg., longitude l = 220 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2328937

We obtain a following upper limits.  

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

   27145 | 2023-12-10 20:46:45 |   MASTER-Kislovodsk | (08h 59m 31.68s , +18d 04m 42.0s) |   C |   180 | 19.2 |        
   27346 | 2023-12-10 20:50:06 |   MASTER-Kislovodsk | (09h 07m 50.50s , +18d 03m 47.1s) |   C |   180 | 19.5 |        
   28358 | 2023-12-10 21:06:58 |   MASTER-Kislovodsk | (08h 59m 28.83s , +18d 05m 01.2s) |   C |   180 | 19.6 |        
   28559 | 2023-12-10 21:10:19 |   MASTER-Kislovodsk | (09h 07m 54.64s , +18d 03m 27.1s) |   C |   180 | 19.3 |        
   29491 | 2023-12-10 21:25:51 |         MASTER-SAAO | (09h 11m 03.56s , +00d 13m 21.3s) |   C |   180 | 19.2 |        
Filter C is a clear (unfiltred) band. 


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