TITLE:   GCN CIRCULAR
NUMBER:  29833
SUBJECT: Fermi GRB 210419B: Global MASTER-Net observations report 
DATE:    21/04/20 00:00:07 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-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 210419B ( Fermi GBM team, GCN 29831) errorbox  8248 sec after notice time and 8274 sec after trigger time at 2021-04-19 23:28:23 UT, with upper limit up to  16.1 mag. The observations began at zenith distance = 71 deg. The sun  altitude  is -27.1 deg. 

The galactic latitude b = -22 deg., longitude l = 45 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1596170

We obtain a following upper limits.  

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

    8305 | 2021-04-19 23:28:23 |   MASTER-Kislovodsk | (20h 27m 02.66s , +00d 07m 45.8s) |   C |    60 | 13.7 |        
    8543 | 2021-04-19 23:32:21 |   MASTER-Kislovodsk | (20h 19m 02.82s , +00d 06m 53.2s) |   C |    60 | 16.1 |        
    8860 | 2021-04-19 23:37:38 |   MASTER-Kislovodsk | (20h 19m 55.36s , +02d 08m 29.6s) |   C |    60 | 14.7 |        
    8940 | 2021-04-19 23:38:58 |   MASTER-Kislovodsk | (20h 27m 46.29s , -01d 51m 11.2s) |   C |    60 | 14.2 |        
    9257 | 2021-04-19 23:44:15 |   MASTER-Kislovodsk | (20h 27m 02.09s , +00d 07m 54.1s) |   C |    60 | 15.1 |        
    9337 | 2021-04-19 23:45:35 |   MASTER-Kislovodsk | (20h 35m 01.94s , +00d 08m 45.7s) |   C |    60 | 15.0 |        
    9496 | 2021-04-19 23:48:14 |   MASTER-Kislovodsk | (20h 19m 07.83s , +00d 07m 34.0s) |   C |    60 | 12.6 |        
Filter C is a clear (unfiltred) band. 


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