TITLE:   GCN CIRCULAR
NUMBER:  33844
SUBJECT: Fermi  trigger No 706328428: Global MASTER-Net observations report
DATE:    23/05/21 18:30:44 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>

V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, 
G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov,  D.Cheryasov, Ya.Kechin
(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
(Irkutsk State University, API),

L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez 
(INAOE, Guillermo Haro Astrophysics Observatory),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

A. Gabovich, V.Yurkov 
(Blagoveschensk Educational State University)


MASTER-Amur robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Blagoveshchensk State Pedagogical University) started inspect of the Fermi GRB230521.10 (trigger No 706328428,03h 09m 24.00s , +22d 24m 00.0s, R=20.7833) errorbox  51447 sec after notice time and 51478 sec after trigger time at 2023-05-21 16:38:22 UT, with upper limit up to  15.7 mag. The observations began at zenith distance = 85 deg. The sun  altitude  is -18.1 deg. 

The galactic latitude b = -30 deg., longitude l = 161 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2217885

We obtain a following upper limits.  

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

   51569 | 2023-05-21 16:38:22 |         MASTER-Amur | (02h 10m 05.21s , +37d 24m 21.1s) |   C |   180 | 13.8 |        
   53309 | 2023-05-21 17:07:22 |         MASTER-Amur | (02h 06m 58.70s , +35d 30m 02.6s) |   C |   180 | 15.7 |        
   53521 | 2023-05-21 17:10:54 |         MASTER-Amur | (02h 04m 11.90s , +33d 37m 56.1s) |   C |   180 | 15.6 |        
   54413 | 2023-05-21 17:25:46 |         MASTER-Amur | (02h 01m 42.41s , +31d 42m 14.7s) |   C |   180 | 15.6 |        
   56418 | 2023-05-21 17:59:11 |         MASTER-Amur | (02h 01m 40.50s , +31d 42m 16.9s) |   C |   180 | 14.6 |        
Filter C is a clear (unfiltred) band. 


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