TITLE:   GCN CIRCULAR
NUMBER:  34858
SUBJECT: Fermi GRB 231020A: Global MASTER-Net observations report
DATE:    23/10/20 19:30:48 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>

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 GRB 231020A ( Fermi GBM team, GCN 34856) errorbox  510 sec after notice time and 519 sec after trigger time at 2023-10-20 19:05:37 UT, with upper limit up to  16.7 mag. The observations began at zenith distance = 80 deg. The sun  altitude  is -49.5 deg. 

The galactic latitude b = -42 deg., longitude l = 18 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2289661

We obtain a following upper limits.  

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

     569 | 2023-10-20 19:05:37 |   MASTER-Kislovodsk | (21h 11m 20.75s , -28d 16m 42.1s) |  P| |   100 | 16.5 |        
     705 | 2023-10-20 19:07:37 |   MASTER-Kislovodsk | (21h 11m 26.12s , -28d 17m 47.5s) |  P| |   130 | 16.7 |        
     870 | 2023-10-20 19:10:08 |   MASTER-Kislovodsk | (21h 11m 20.36s , -28d 18m 56.3s) |  P| |   160 | 16.7 |        


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