GCN Circular 36268

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 IceCube Alert 240424.08 (trigger No 50057906,21h 46m 07.20s , +03d 09m 43.2s, R=1.27) errorbox  24 sec after notice time and 62 sec after trigger time at 2024-04-24 01:50:28 UT, with upper limit up to  16.4 mag. The observations began at zenith distance = 71 deg. The sun  altitude  is -41.8 deg. 

The galactic latitude b = -36 deg., longitude l = 60 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2433992

We obtain a following upper limits.  

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

      68 | 2024-04-24 01:50:28 |         MASTER-SAAO | (21h 44m 16.95s , +02d 50m 02.1s) |   C |    10 | 15.6 |        
      68 | 2024-04-24 01:50:28 |         MASTER-SAAO | (21h 42m 29.64s , +03d 03m 19.8s) |   C |    10 | 16.1 |        
      97 | 2024-04-24 01:50:58 |         MASTER-SAAO | (21h 44m 16.99s , +02d 50m 02.0s) |   C |    10 | 15.7 |        
      97 | 2024-04-24 01:50:58 |         MASTER-SAAO | (21h 42m 29.67s , +03d 03m 19.2s) |   C |    10 | 16.0 |        
     131 | 2024-04-24 01:51:27 |         MASTER-SAAO | (21h 44m 17.02s , +02d 50m 02.2s) |   C |    20 | 15.9 |        
     131 | 2024-04-24 01:51:27 |         MASTER-SAAO | (21h 42m 29.67s , +03d 03m 19.2s) |   C |    20 | 16.3 |        
     176 | 2024-04-24 01:52:07 |         MASTER-SAAO | (21h 44m 17.05s , +02d 50m 02.2s) |   C |    30 | 15.9 |        
     176 | 2024-04-24 01:52:07 |         MASTER-SAAO | (21h 42m 29.69s , +03d 03m 19.0s) |   C |    30 | 16.3 |        
     230 | 2024-04-24 01:52:56 |         MASTER-SAAO | (21h 44m 17.08s , +02d 50m 02.0s) |   C |    40 | 15.8 |        
     230 | 2024-04-24 01:52:56 |         MASTER-SAAO | (21h 42m 29.69s , +03d 03m 18.5s) |   C |    40 | 16.0 |        
     295 | 2024-04-24 01:53:55 |         MASTER-SAAO | (21h 44m 17.11s , +02d 50m 01.9s) |   C |    50 | 15.9 |        
     295 | 2024-04-24 01:53:55 |         MASTER-SAAO | (21h 42m 29.68s , +03d 03m 18.3s) |   C |    50 | 16.1 |        
     369 | 2024-04-24 01:55:05 |         MASTER-SAAO | (21h 44m 17.12s , +02d 50m 01.6s) |   C |    60 | 16.0 |        
     369 | 2024-04-24 01:55:05 |         MASTER-SAAO | (21h 42m 29.65s , +03d 03m 17.9s) |   C |    60 | 16.2 |        
     448 | 2024-04-24 01:56:24 |         MASTER-SAAO | (21h 44m 17.11s , +02d 50m 01.4s) |   C |    60 | 16.0 |        
     448 | 2024-04-24 01:56:24 |         MASTER-SAAO | (21h 42m 29.58s , +03d 03m 17.5s) |   C |    60 | 16.0 |        
     528 | 2024-04-24 01:57:44 |         MASTER-SAAO | (21h 44m 17.11s , +02d 50m 01.4s) |   C |    60 | 16.0 |        
     528 | 2024-04-24 01:57:44 |         MASTER-SAAO | (21h 42m 29.53s , +03d 03m 17.3s) |   C |    60 | 16.3 |        
     607 | 2024-04-24 01:59:03 |         MASTER-SAAO | (21h 44m 17.09s , +02d 50m 01.1s) |   C |    60 | 16.2 |        
     607 | 2024-04-24 01:59:03 |         MASTER-SAAO | (21h 42m 29.48s , +03d 03m 17.0s) |   C |    60 | 16.4 |        
     687 | 2024-04-24 02:00:22 |         MASTER-SAAO | (21h 44m 17.07s , +02d 50m 00.7s) |   C |    60 | 16.2 |        
     687 | 2024-04-24 02:00:22 |         MASTER-SAAO | (21h 42m 29.44s , +03d 03m 16.7s) |   C |    60 | 16.3 |        
Filter C is a clear (unfiltred) band. 


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