TITLE:   GCN CIRCULAR
NUMBER:  32871
SUBJECT: Swift GRB 221027B: Global MASTER-Net observations report 
DATE:    22/10/28 07:12:31 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-Tavrida robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the Swift GRB 221027B ( A. Y. Lien et al., GCN 32867) errorbox  21757 sec after notice time and 22094 sec after trigger time at 2022-10-28 01:21:53 UT, with upper limit up to  18.5 mag. The observations began at zenith distance = 79 deg. The sun  altitude  is -31.2 deg. 

The galactic latitude b = 57 deg., longitude l = 80 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2136676

We obtain a following upper limits.  

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

   22185 |      MASTER-Tavrida |   C |   180 | 17.6 |        
   22185 |      MASTER-Tavrida |   C |   180 | 15.2 |        
   22376 |      MASTER-Tavrida |   C |   180 | 17.9 |        
   22376 |      MASTER-Tavrida |   C |   180 | 15.1 |        
   22662 |      MASTER-Tavrida |   C |   180 | 18.3 |        
   22662 |      MASTER-Tavrida |   C |   180 | 15.4 |        
   23028 |      MASTER-Tavrida |   C |   180 | 18.3 |        
   23028 |      MASTER-Tavrida |   C |   180 | 16.0 |        
   23985 |      MASTER-Tavrida |   C |   180 | 18.5 |        
   23985 |      MASTER-Tavrida |   C |   180 | 18.0 |        
Filter C is a clear (unfiltred) band. 


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