GCN Circular 36198

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) was pointed to the IceCube Alert 240419.98 (trigger No 27647445,04h 56m 36.72s , +01d 04m 48.0s, R=0.93) errorbox  62953 sec after notice time and 63005 sec after trigger time at 2024-04-20 16:55:46 UT, with upper limit up to  17.8 mag. Observations started at twilight.  The observations began at zenith distance = 59 deg. The sun  altitude  is -10.0 deg. 

MASTER-Kislovodsk robotic telescope  located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the IceCube Alert 240419.98 errorbox  63247 sec after notice time and 63298 sec after trigger time at 2024-04-20 17:00:39 UT, with upper limit up to  14.6 mag. Observations started at twilight.  The observations began at zenith distance = 77 deg. The sun  altitude  is -11.3 deg. 

The galactic latitude b = -24 deg., longitude l = 198 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2428145

We obtain a following upper limits.  

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

   63036 | 2024-04-20 16:55:46 |         MASTER-SAAO | (04h 46m 18.98s , +01d 16m 48.1s) |   C |    60 | 16.5 |        
   63036 | 2024-04-20 16:55:46 |         MASTER-SAAO | (04h 48m 02.63s , +01d 04m 23.4s) |   C |    60 | 16.0 |        
   63389 | 2024-04-20 17:00:39 |   MASTER-Kislovodsk | (04h 49m 31.32s , +01d 55m 29.2s) |   C |   180 | 12.4 |        
   64055 | 2024-04-20 17:12:46 |         MASTER-SAAO | (04h 48m 01.33s , +01d 04m 01.3s) |   C |    60 | 16.1 |        
   64561 | 2024-04-20 17:21:11 |         MASTER-SAAO | (04h 48m 31.66s , +02d 57m 38.3s) |   C |    60 | 17.6 |        
   64940 | 2024-04-20 17:27:30 |   MASTER-Kislovodsk | (05h 04m 41.95s , +01d 08m 28.7s) |   C |    60 | 14.3 |        
   64940 | 2024-04-20 17:27:30 |   MASTER-Kislovodsk | (05h 01m 00.38s , +01d 29m 17.0s) |   C |    60 | 14.6 |        
   65020 | 2024-04-20 17:28:50 |   MASTER-Kislovodsk | (05h 01m 16.88s , +03d 24m 39.7s) |   C |    60 | 14.1 |        
   65020 | 2024-04-20 17:28:50 |   MASTER-Kislovodsk | (05h 04m 59.16s , +03d 03m 48.3s) |   C |    60 | 13.9 |        
   65096 | 2024-04-20 17:30:06 |         MASTER-SAAO | (04h 48m 11.29s , +01d 05m 32.6s) |   C |    60 | 17.8 |        
   65639 | 2024-04-20 17:39:10 |         MASTER-SAAO | (04h 48m 38.09s , +02d 59m 01.1s) |   C |    60 | 16.4 |        
   65732 | 2024-04-20 17:40:42 |         MASTER-SAAO | (05h 03m 11.15s , -00d 49m 58.1s) |   C |    60 | 16.9 |        
   65824 | 2024-04-20 17:42:14 |         MASTER-SAAO | (04h 48m 11.49s , -00d 49m 49.2s) |   C |    60 | 17.0 |        
   66581 | 2024-04-20 17:53:51 |         MASTER-SAAO | (04h 52m 10.45s , +01d 32m 00.0s) |   C |   180 | 15.7 |        
   66734 | 2024-04-20 17:57:25 |         MASTER-SAAO | (05h 03m 17.66s , -00d 49m 18.7s) |   C |    60 | 17.0 |        
   66826 | 2024-04-20 17:58:57 |         MASTER-SAAO | (04h 48m 19.58s , -00d 49m 09.1s) |   C |    60 | 17.1 |        
   67589 | 2024-04-20 18:10:40 |         MASTER-SAAO | (04h 52m 21.99s , +01d 32m 36.8s) |   C |   180 | 15.3 |        
   67742 | 2024-04-20 18:14:13 |         MASTER-SAAO | (05h 03m 25.14s , -00d 48m 42.1s) |   C |    60 | 16.8 |        
   67835 | 2024-04-20 18:15:45 |         MASTER-SAAO | (04h 48m 33.70s , -00d 48m 23.9s) |   C |    60 | 17.0 |        
Filter C is a clear (unfiltred) band. 


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