GRB 210619.99

V. Lipunov, E. Gorbovskoy, V.Kornilov, D.Kuvshinov, N.Tyurina, P.Balanutsa,
A.Kuznetsov, D. Vlasenko, F. Balakin, I. Gorbunov
Lomonosov Moscow State University,
Sternberg Astronomical Institute, Moscow State University

D. Buckley, S. Potter, A. Kniazev, M. Kotze
South African Astronomical Observatory

K. Ivanov, O. Gres, N.M. Budnev, S. Yazev, O. Chuvalaev, V. Poleshchuk
Irkutsk State University

A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory

V. Yurkov, A. Gabovich, Yu. Sergienko
Blagoveschensk Educational State University, Blagoveschensk

R. Podesta, Carlos Lopez and F. Podesta
Observatorio Astronomico Felix Aguilar (OAFA)

R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias

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) was pointed to the  GRB210619.99 22 sec after notice time and 36 sec after trigger time at 2021-06-20 00:00:02 UT. On our first (10s exposure)  set we  found 1 optical transient within Swift error-box (ra=319.708 dec=33.86 r=0.05) brighter than  15.3.


 T-Tmid      Date      Time       Expt.        Ra                Dec           Mag
---------|---------------------|-------|-----------------|-----------------|-------
      41   2021-06-20 00:00:02      10   (21h 18m 52.35s , +33d 51m 01.4s)     10.4

The 5-sigma upper limit has been about  15.3mag
The message may be cited.

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) was pointed to the Swift GRB210619.99 (trigger No 1056757,21h 18m 51.12s , +33d 51m 36.0s, R=0.05) errorbox  0 sec after notice time and 36 sec after trigger time at 2021-06-20 00:00:02 UT, with upper limit up to  16.7 mag. The observations began at zenith distance = 72 deg. The sun  altitude  is -70.4 deg. 

The galactic latitude b = -11 deg., longitude l = 81 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1640637

We obtain a following upper limits.  

Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

      42 |         MASTER-SAAO | P\  |    10 | 15.8 |        
      57 |         MASTER-SAAO | P\  |    40 | 16.5 |  Coadd 
      71 |         MASTER-SAAO | P\  |    10 | 15.6 |        
     106 |         MASTER-SAAO | P\  |    20 | 16.2 |        
     150 |         MASTER-SAAO | P\  |    30 | 16.5 |        
     205 |         MASTER-SAAO | P\  |    40 | 16.4 |        
     269 |         MASTER-SAAO | P\  |    50 | 16.7 |        
     344 |         MASTER-SAAO | P\  |    60 | 16.7 |        


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

V. Lipunov, E. Gorbovskoy, V.Kornilov, D.Kuvshinov, N.Tyurina, P.Balanutsa,
A.Kuznetsov, D. Vlasenko, F. Balakin, I. Gorbunov
Lomonosov Moscow State University,
Sternberg Astronomical Institute, Moscow State University

R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias

K. Ivanov, O. Gres, N.M. Budnev, S. Yazev, O. Chuvalaev, V. Poleshchuk
Irkutsk State University

A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory

V. Yurkov, A. Gabovich, Yu. Sergienko
Blagoveschensk Educational State University, Blagoveschensk


D. Buckley, S. Potter, A. Kniazev, M. Kotze
South African Astronomical Observatory

R. Podesta, Carlos Lopez and F. Podesta
Observatorio Astronomico Felix Aguilar (OAFA)

MASTER-IAC robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Spain (IAC Teide Observatory) was pointed to the  GRB210619.99 23 sec after notice time and 37 sec after trigger time at 2021-06-20 00:00:03 UT. On our first (10s exposure)  set we  found 1 optical transient within Swift error-box (ra=319.713 dec=33.86 r=0.05) brighter than  15.6.


 T-Tmid      Date      Time       Expt.        Ra                Dec           Mag
---------|---------------------|-------|-----------------|-----------------|-------
      42   2021-06-20 00:00:03      10   (21h 18m 52.38s , +33d 51m 01.4s)     10.7

The 5-sigma upper limit has been about  15.6mag
The message may be cited.