TITLE:   GCN CIRCULAR
NUMBER:  28487
SUBJECT: IceCube Alert 200921.80: Global MASTER-Net observations report 
DATE:    20/09/23 21:13:10 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-Tunka robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Applied Physics Institute, Irkutsk State University) was pointed to the IceCube Alert 200921.80 (trigger No 71996695,13h 00m 47.28s , +26d 25m 48.0s, R=0.51) errorbox  1 days 64942 sec after notice time and 1 days 65023 sec after trigger time at 2020-09-23 13:10:56 UT, with upper limit up to  17.4 mag. The observations began at zenith distance = 80 deg. The sun  altitude  is -20.2 deg. 

The galactic latitude b = 87 deg., longitude l = 13 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1445930

We obtain a following upper limits.  

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

  151514 | 2020-09-23 13:10:56 |        MASTER-Tunka | (13h 01m 31.51s , +26d 37m 02.0s) |   C |   180 | 17.1 |        
  151713 | 2020-09-23 13:14:15 |        MASTER-Tunka | (13h 01m 36.54s , +26d 35m 50.5s) |   C |   180 | 17.1 |        
  151913 | 2020-09-23 13:17:35 |        MASTER-Tunka | (13h 01m 30.54s , +26d 34m 42.7s) |   C |   180 | 17.4 |        
  152112 | 2020-09-23 13:20:54 |        MASTER-Tunka | (13h 01m 36.71s , +26d 34m 39.1s) |   C |   180 | 17.4 |        
  152311 | 2020-09-23 13:24:14 |        MASTER-Tunka | (13h 01m 33.97s , +26d 36m 08.7s) |   C |   180 | 16.9 |        
  152511 | 2020-09-23 13:27:33 |        MASTER-Tunka | (13h 01m 34.00s , +26d 34m 54.3s) |   C |   180 | 17.0 |        
  152710 | 2020-09-23 13:30:53 |        MASTER-Tunka | (13h 01m 37.00s , +26d 35m 54.6s) |   C |   180 | 16.9 |        
  152910 | 2020-09-23 13:34:12 |        MASTER-Tunka | (13h 01m 31.81s , +26d 35m 18.6s) |   C |   180 | 16.7 |        
  153109 | 2020-09-23 13:37:31 |        MASTER-Tunka | (13h 01m 31.93s , +26d 36m 14.7s) |   C |   180 | 16.5 |        
  153308 | 2020-09-23 13:40:51 |        MASTER-Tunka | (13h 01m 38.44s , +26d 35m 09.0s) |   C |   180 | 16.5 |        
  153508 | 2020-09-23 13:44:10 |        MASTER-Tunka | (13h 01m 32.31s , +26d 34m 02.6s) |   C |   180 | 16.4 |        
  153707 | 2020-09-23 13:47:30 |        MASTER-Tunka | (13h 01m 38.05s , +26d 34m 17.3s) |   C |   180 | 15.5 |        
Filter C is a clear (unfiltred) band. 


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