TITLE:   GCN CIRCULAR
NUMBER:  28018
SUBJECT: Fermi GRB 200623B: Global MASTER-Net observations report 
DATE:    20/06/23 18:30:18 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),

H.Levato 
(Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE),

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 200623B ( Fermi GBM team, GCN 28017) errorbox  552 sec after notice time and 590 sec after trigger time at 2020-06-23 18:12:39 UT, with upper limit up to  18.9 mag. The observations began at zenith distance = 74 deg. The sun  altitude  is -30.9 deg. 

The galactic latitude b = -43 deg., longitude l = 328 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1388895

We obtain a following upper limits.  

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

     620 | 2020-06-23 18:12:39 |         MASTER-SAAO | (21h 51m 50.01s , -64d 03m 54.4s) |   C |    60 | 18.6 |        
     713 | 2020-06-23 18:14:12 |         MASTER-SAAO | (22h 08m 29.53s , -66d 03m 58.4s) |   C |    60 | 18.9 |        
     713 | 2020-06-23 18:14:12 |         MASTER-SAAO | (22h 25m 14.90s , -66d 03m 19.6s) |   C |    60 | 18.6 |        
     793 | 2020-06-23 18:15:32 |         MASTER-SAAO | (22h 37m 18.63s , -68d 05m 13.2s) |   C |    60 | 18.9 |        
     793 | 2020-06-23 18:15:32 |         MASTER-SAAO | (22h 55m 31.23s , -68d 04m 31.7s) |   C |    60 | 18.7 |        
Filter C is a clear (unfiltred) band. 


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