TITLE:   GCN CIRCULAR
NUMBER:  29395
SUBJECT: Fermi GRB 210204A: Global MASTER-Net observations report 
DATE:    21/02/05 01:45:09 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 210204A ( Fermi GBM team, GCN 29390) errorbox  60315 sec after notice time and 60380 sec after trigger time at 2021-02-04 23:15:45 UT, with upper limit up to  19.5 mag. The observations began at zenith distance = 53 deg. The sun  altitude  is -41.7 deg. 

The galactic latitude b = 10 deg., longitude l = 207 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1539740

We obtain a following upper limits.  

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

   60410 | 2021-02-04 23:15:45 |         MASTER-SAAO | (07h 36m 18.07s , +12d 00m 15.6s) |   C |    60 | 19.5 |        
   60650 | 2021-02-04 23:19:45 |         MASTER-SAAO | (07h 33m 16.34s , +10d 00m 28.3s) |   C |    60 | 19.4 |        
   61528 | 2021-02-04 23:34:23 |         MASTER-SAAO | (07h 36m 15.36s , +12d 02m 18.2s) |   C |    60 | 19.3 |        
   62007 | 2021-02-04 23:42:22 |         MASTER-SAAO | (07h 33m 06.36s , +10d 00m 56.4s) |   C |    60 | 19.4 |        
   62087 | 2021-02-04 23:43:42 |         MASTER-SAAO | (07h 37m 16.25s , +10d 01m 05.7s) |   C |    60 | 19.4 |        
   62845 | 2021-02-04 23:56:20 |         MASTER-SAAO | (07h 36m 14.47s , +12d 01m 44.5s) |   C |    60 | 19.4 |        
   63325 | 2021-02-05 00:04:21 |         MASTER-SAAO | (07h 33m 07.78s , +10d 02m 43.9s) |   C |    60 | 19.4 |        
   63503 | 2021-02-05 00:07:18 |         MASTER-SAAO | (07h 37m 07.26s , +10d 03m 31.2s) |   C |    60 | 19.4 |        
   64498 | 2021-02-05 00:23:53 |         MASTER-SAAO | (07h 37m 02.39s , +10d 02m 11.3s) |   C |    60 | 19.0 |        
Filter C is a clear (unfiltred) band. 


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