TITLE:   GCN CIRCULAR
NUMBER:  29378
SUBJECT: Fermi  trigger No 633879387: Global MASTER-Net observations report 
DATE:    21/02/01 19:30:09 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 GRB210201.57 (trigger No 633879387,11h 24m 28.80s , -40d 48m 36.0s, R=10.44) errorbox  18778 sec after notice time and 18805 sec after trigger time at 2021-02-01 18:49:48 UT, with upper limit up to  18.1 mag. Observations started at twilight.  The observations began at zenith distance = 75 deg. The sun  altitude  is -14.1 deg. 

The galactic latitude b = 19 deg., longitude l = 286 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1537090

We obtain a following upper limits.  

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

   18836 | 2021-02-01 18:49:48 |         MASTER-SAAO | (11h 27m 09.42s , -39d 57m 35.7s) |   C |    60 | 17.5 |        
   18917 | 2021-02-01 18:51:09 |         MASTER-SAAO | (11h 26m 46.57s , -41d 58m 18.0s) |   C |    60 | 17.8 |        
   18997 | 2021-02-01 18:52:29 |         MASTER-SAAO | (11h 27m 14.43s , -43d 58m 11.0s) |   C |    60 | 17.6 |        
   19080 | 2021-02-01 18:53:52 |         MASTER-SAAO | (11h 05m 10.25s , -41d 58m 00.9s) |   C |    60 | 18.0 |        
   19161 | 2021-02-01 18:55:13 |         MASTER-SAAO | (11h 06m 17.03s , -39d 58m 02.0s) |   C |    60 | 18.0 |        
   19243 | 2021-02-01 18:56:35 |         MASTER-SAAO | (11h 28m 15.87s , -37d 58m 16.7s) |   C |    60 | 17.6 |        
   19645 | 2021-02-01 19:03:17 |         MASTER-SAAO | (11h 07m 53.23s , -37d 58m 13.8s) |   C |    60 | 18.1 |        
   19725 | 2021-02-01 19:04:37 |         MASTER-SAAO | (11h 05m 04.00s , -43d 58m 12.7s) |   C |    60 | 18.1 |        
   19805 | 2021-02-01 19:05:57 |         MASTER-SAAO | (11h 27m 03.50s , -39d 58m 49.6s) |   C |    60 | 17.9 |        
   19885 | 2021-02-01 19:07:17 |         MASTER-SAAO | (11h 32m 21.82s , -39d 58m 27.6s) |   C |    60 | 17.9 |        
   19976 | 2021-02-01 19:08:48 |         MASTER-SAAO | (11h 26m 44.66s , -41d 57m 10.7s) |   C |    60 | 17.8 |        
   20144 | 2021-02-01 19:11:36 |         MASTER-SAAO | (11h 32m 10.35s , -41d 56m 55.1s) |   C |    60 | 17.9 |        
   20232 | 2021-02-01 19:13:04 |         MASTER-SAAO | (11h 27m 11.45s , -43d 57m 50.5s) |   C |    60 | 17.7 |        
Filter C is a clear (unfiltred) band. 


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