TITLE:   GCN CIRCULAR
NUMBER:  39358
SUBJECT: Fermi GRB 250217C: Global MASTER-Net observations report
DATE:    25/02/18 00:16:58 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>

V.Lipunov, E.Gorbovskoy, N.Tiurina,  P.Balanutsa, , D.Vlasenko, I.Panchenko,
A.Kuznetsov,  G.Antipov,  A.Sankovich, A.Sosnovskij, Yu.Tselik, M.Gulyaev, Ya.Kechin,
V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU),
O.Gress, N.Budnev (ISU),
C.Francile,  F. Podesta, R.Podesta, E. Gonzalez  (Observatorio Astronomico Felix Aguilar (OAFA),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity)
D.Buckley (SAAO),
R.Rebolo (The Instituto de Astrofisica de Canarias),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) 

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 250217C ( Fermi GBM team, GCN 39357) errorbox  588 sec after notice time and 626 sec after trigger time at 2025-02-18 00:05:08 UT, with upper limit up to  18.5 mag. The observations began at zenith distance = 74 deg. The sun  altitude  is -42.9 deg. 

The galactic latitude b = 38 deg., longitude l = 191 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2781342

We obtain a following upper limits.  

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

     657 | 2025-02-18 00:05:08 |         MASTER-SAAO | (08h 45m 43.52s , +32d 50m 06.0s) |   C |    60 | 17.9 |        
     717 | 2025-02-18 00:05:08 |         MASTER-SAAO | (08h 45m 43.52s , +32d 50m 05.9s) |   C |   180 | 18.5 |  Coadd 
     736 | 2025-02-18 00:06:27 |         MASTER-SAAO | (08h 45m 43.62s , +32d 50m 10.7s) |   C |    60 | 17.6 |        
     815 | 2025-02-18 00:07:46 |         MASTER-SAAO | (08h 45m 43.81s , +32d 50m 10.7s) |   C |    60 | 17.5 |        
     894 | 2025-02-18 00:09:05 |         MASTER-SAAO | (08h 45m 44.00s , +32d 50m 14.7s) |   C |    60 | 17.6 |        
Filter C is a clear (unfiltred) band. 


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