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GCN Circular 36212

Subject
Fermi GRB 240421A: Global MASTER-Net observations report
Date
2024-04-21T18:16:47Z (12 days 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-SAAO robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 240421A ( Fermi GBM team, GCN 36204Not found
 
 
) errorbox  42622 sec after notice time and 42658 sec after trigger time at 2024-04-21 17:12:58 UT, with upper limit up to  16.7 mag. Observations started at twilight.  The observations began at zenith distance = 66 deg. The sun  altitude  is -13.9 deg. 

The galactic latitude b = -32 deg., longitude l = 313 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2430011

We obtain a following upper limits.  

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

   42689 | 2024-04-21 17:12:58 |         MASTER-SAAO | (20h 50m 46.74s , -82d 18m 27.9s) |   C |    60 | 14.2 |        
   42689 | 2024-04-21 17:12:58 |         MASTER-SAAO | (21h 03m 23.96s , -82d 31m 37.4s) |   C |    60 | 14.4 |        
   42768 | 2024-04-21 17:14:18 |         MASTER-SAAO | (20h 29m 07.64s , -78d 43m 31.0s) |   C |    60 | 14.5 |        
   42768 | 2024-04-21 17:14:18 |         MASTER-SAAO | (20h 20m 41.90s , -78d 30m 17.8s) |   C |    60 | 14.2 |        
   43087 | 2024-04-21 17:19:37 |         MASTER-SAAO | (20h 24m 07.82s , -84d 24m 28.5s) |   C |    60 | 16.7 |        
   43087 | 2024-04-21 17:19:37 |         MASTER-SAAO | (20h 07m 14.94s , -84d 11m 11.3s) |   C |    60 | 16.6 |        
   43167 | 2024-04-21 17:20:56 |         MASTER-SAAO | (19h 08m 34.69s , -82d 29m 18.5s) |   C |    60 | 15.9 |        
   43167 | 2024-04-21 17:20:56 |         MASTER-SAAO | (18h 55m 46.97s , -82d 15m 59.6s) |   C |    60 | 15.8 |        
Filter C is a clear (unfiltred) band. 


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