TITLE:   GCN CIRCULAR
NUMBER:  33581
SUBJECT: IceCube Alert 230405.56: Global MASTER-Net observations report 
DATE:    23/04/06 17:39:21 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, 
G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov,  D.Cheryasov, Ya.Kechin
(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
(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),

A. Gabovich, V.Yurkov 
(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 230405.56 (trigger No 8756840,07h 55m 59.76s , +10d 19m 37.2s, R=1.16) errorbox  1 days 14165 sec after notice time and 1 days 14211 sec after trigger time at 2023-04-06 17:17:11 UT, with upper limit up to  17.9 mag. Observations started at twilight.  The observations began at zenith distance = 43 deg. The sun  altitude  is -11.0 deg. 

The galactic latitude b = 20 deg., longitude l = 211 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2208828

We obtain a following upper limits.  

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

  100702 | 2023-04-06 17:17:11 |         MASTER-SAAO | (07h 55m 20.19s , +10d 20m 15.0s) |   C |   180 | 16.9 |        
  100702 | 2023-04-06 17:17:11 |         MASTER-SAAO | (07h 56m 10.87s , +10d 20m 40.2s) |   C |   180 | 16.3 |        
  100853 | 2023-04-06 17:20:43 |         MASTER-SAAO | (07h 54m 49.03s , +10d 40m 45.6s) |   C |    60 | 17.7 |        
  100853 | 2023-04-06 17:20:43 |         MASTER-SAAO | (07h 55m 39.89s , +10d 41m 11.0s) |   C |    60 | 17.4 |        
  100933 | 2023-04-06 17:22:03 |         MASTER-SAAO | (08h 03m 01.21s , +10d 41m 11.4s) |   C |    60 | 17.7 |        
  100933 | 2023-04-06 17:22:03 |         MASTER-SAAO | (08h 03m 52.04s , +10d 41m 36.8s) |   C |    60 | 17.5 |        
  101024 | 2023-04-06 17:23:34 |         MASTER-SAAO | (07h 52m 14.56s , +08d 47m 14.1s) |   C |    60 | 17.9 |        
  101024 | 2023-04-06 17:23:34 |         MASTER-SAAO | (07h 53m 05.27s , +08d 47m 39.5s) |   C |    60 | 17.6 |        
  101104 | 2023-04-06 17:24:53 |         MASTER-SAAO | (08h 00m 19.65s , +08d 48m 36.6s) |   C |    60 | 17.9 |        
  101104 | 2023-04-06 17:24:53 |         MASTER-SAAO | (08h 01m 10.45s , +08d 49m 01.9s) |   C |    60 | 17.8 |        
Filter C is a clear (unfiltred) band. 


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