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GCN Circular 35766

Subject
Swift GRB240221.92: Global MASTER-Net observations report
Date
2024-02-21T22:56:27Z (2 months ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
legacy email
V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik,  D. Vlasenko,
G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij
(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. Gress, N.M. Budnev, O.Ershova
(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),

V. Yurkov, A. Gabovich
(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 Swift GRB240221.92 (trigger No 1216743,16h 21m 22.32s , -15d 40m 33.6s, R=0.00130556) errorbox  2112 sec after notice time and 2135 sec after trigger time at 2024-02-21 22:44:39 UT, with upper limit up to  17.9 mag. Observations started at twilight.  The observations began at zenith distance = 67 deg. The sun  altitude  is -13.8 deg. 

The galactic latitude b = 23 deg., longitude l = 360 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2383502

We obtain a following upper limits.  

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

    2146 |        MASTER-Tunka |   C |    20 | 17.4 |        
    2166 |        MASTER-Tunka |   C |    60 | 17.9 |  Coadd 
    2176 |        MASTER-Tunka |   C |    20 | 17.2 |        
    2208 |        MASTER-Tunka |   C |    20 | 17.2 |        
    2239 |        MASTER-Tunka |   C |    20 | 17.4 |        
    2268 |        MASTER-Tunka |   C |    15 | 17.2 |        
    2292 |        MASTER-Tunka |   C |    15 | 16.9 |        
    2319 |        MASTER-Tunka |   C |    15 | 17.2 |        
    2343 |        MASTER-Tunka |   C |    15 | 17.1 |        
    2461 |        MASTER-Tunka |   C |    15 | 17.2 |        
    2485 |        MASTER-Tunka |   C |    15 | 17.0 |        
    2596 |        MASTER-Tunka |   C |    15 | 17.2 |        
Filter C is a clear (unfiltred) band. 


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