TITLE:   GCN CIRCULAR
NUMBER:  29396
SUBJECT: Fermi GRB 210204B: Global MASTER-Net observations report 
DATE:    21/02/05 01:45:22 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(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. Gres, N.M. Budnev, O.Ershova 
(Irkutsk State University, API),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

V. Yurkov, A. Gabovich, Yu. Sergienko 
(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 GRB 210204B ( Fermi GBM team, GCN 29394) errorbox  19603 sec after notice time and 19610 sec after trigger time at 2021-02-05 00:05:50 UT, with upper limit up to  18.1 mag. The observations began at zenith distance = 75 deg. The sun  altitude  is -38.9 deg. 

The galactic latitude b = -17 deg., longitude l = 339 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1540065

We obtain a following upper limits.  

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

   19640 | 2021-02-05 00:05:50 |         MASTER-SAAO | (18h 03m 24.86s , -58d 03m 48.4s) |   C |    60 | 17.7 |        
   20217 | 2021-02-05 00:15:26 |         MASTER-SAAO | (18h 03m 55.82s , -56d 04m 08.1s) |   C |    60 | 17.8 |        
   20555 | 2021-02-05 00:21:04 |         MASTER-SAAO | (18h 03m 18.65s , -58d 02m 16.0s) |   C |    60 | 17.9 |        
   20635 | 2021-02-05 00:22:24 |         MASTER-SAAO | (18h 10m 58.28s , -58d 03m 18.1s) |   C |    60 | 17.9 |        
   20893 | 2021-02-05 00:26:42 |         MASTER-SAAO | (18h 05m 36.28s , -54d 04m 17.6s) |   C |    60 | 17.7 |        
   21132 | 2021-02-05 00:30:41 |         MASTER-SAAO | (18h 03m 50.26s , -56d 04m 25.2s) |   C |    60 | 17.9 |        
   21211 | 2021-02-05 00:32:00 |         MASTER-SAAO | (18h 11m 05.22s , -56d 04m 25.2s) |   C |    60 | 18.0 |        
   21451 | 2021-02-05 00:36:00 |         MASTER-SAAO | (17h 45m 06.55s , -54d 03m 21.5s) |   C |    60 | 17.8 |        
   21530 | 2021-02-05 00:37:19 |         MASTER-SAAO | (18h 03m 17.60s , -58d 02m 28.3s) |   C |    60 | 17.9 |        
   21610 | 2021-02-05 00:38:39 |         MASTER-SAAO | (18h 10m 56.86s , -58d 03m 34.0s) |   C |    60 | 18.1 |        
   21690 | 2021-02-05 00:39:59 |         MASTER-SAAO | (18h 08m 29.00s , -52d 04m 20.4s) |   C |    60 | 17.7 |        
   21769 | 2021-02-05 00:41:19 |         MASTER-SAAO | (18h 32m 31.40s , -56d 04m 30.4s) |   C |    60 | 17.8 |        
   21849 | 2021-02-05 00:42:38 |         MASTER-SAAO | (18h 05m 39.25s , -54d 02m 48.5s) |   C |    60 | 17.9 |        
   21929 | 2021-02-05 00:43:58 |         MASTER-SAAO | (18h 12m 20.73s , -54d 03m 45.5s) |   C |    60 | 17.9 |        
Filter C is a clear (unfiltred) band. 


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