GCN Circular 30626

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-OAFA robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Argentina (OAFA observatory of San Juan National University) was pointed to the IceCube Alert 210811.09 (trigger No 36044887,18h 05m 41.76s , +25d 22m 01.2s, R=0.51) errorbox  48 sec after notice time and 124 sec after trigger time at 2021-08-11 02:04:48 UT, with upper limit up to  17.9 mag. The observations began at zenith distance = 57 deg. The sun  altitude  is -51.3 deg. 

MASTER-IAC robotic telescope  located in Spain (IAC Teide Observatory) was pointed to the IceCube Alert 210811.09 errorbox  51 sec after notice time and 127 sec after trigger time at 2021-08-11 02:04:51 UT, with upper limit up to  17.5 mag. The observations began at zenith distance = 56 deg. The sun  altitude  is -44.5 deg. 

The galactic latitude b = 20 deg., longitude l = 52 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1687110

We obtain a following upper limits.  

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

     129 | 2021-08-11 02:04:48 |         MASTER-OAFA | (18h 03m 39.02s , +24d 39m 22.3s) |   C |    10 | 17.2 |        
     142 | 2021-08-11 02:04:51 |          MASTER-IAC | (18h 05m 06.46s , +25d 19m 43.1s) |  P| |    30 | 17.5 |        
     142 | 2021-08-11 02:04:51 |          MASTER-IAC | (18h 04m 11.29s , +25d 25m 52.8s) |  P- |    30 | 17.2 |        
     164 | 2021-08-11 02:05:17 |         MASTER-OAFA | (18h 03m 42.19s , +24d 41m 00.0s) |   C |    20 | 17.6 |        
     192 | 2021-08-11 02:05:41 |          MASTER-IAC | (18h 05m 06.92s , +25d 20m 44.0s) |  P| |    30 | 17.5 |        
     204 | 2021-08-11 02:05:57 |         MASTER-OAFA | (18h 03m 35.66s , +24d 40m 23.7s) |   C |    20 | 17.6 |        
     250 | 2021-08-11 02:06:38 |         MASTER-OAFA | (18h 03m 34.86s , +24d 41m 26.7s) |   C |    30 | 17.9 |        
Filter C is a clear (unfiltred) band. 


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