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GCN Circular 27455

GRB 200325B: Mondy, CrAO, AbAO afterglow confirmation and refined photometry of MASTER OT J111012.51+274912.8
2020-03-27T13:14:36Z (4 years ago)
Alexei Pozanenko at IKI, Moscow <>
S. Belkin (IKI),  A. Pozanenko (IKI), E. Klunko (ISTP), A. Sosnovskij 
(CrAO), R. Ya. Inasaridze (AbAO), V. Rumyantsev (CrAO), M. Eselevich 
(ISTP), E. Mazaeva (IKI), A. Volnova (IKI) report on behalf of IKI-GRB-FuN:

We observed the  MASTER OT J111012.51+274912.8  (Lipunov et al., GCN 
27446) as a candidate in afterglow of the Fermi GRB 200325B (Fermi GBM 
team, GCN 27441) with AZT-33VM 1.5-m telescope of Sayan observatory 
(Mondy) starting on  2020-03-26 (UT) 15:08:10,  ZTSh 2.6m telescope of 
CrAO starting on 2020-03-26 (UT) 20:11:20 (Pozanenko et al., GCN 27452), 
and AS-32 0.7m telescope of Abastumani observatory starting on 
2020-03-26 (UT) 20:27:39. Below we present refined photometry of the OT.
Preliminary photometry of the object is following.

Date UT start       t-T0  Filter Exp. OT Err UL(3sigma)   telescope
                         (mid, days) (s)
2020-03-26 15:08:10 1.0263   R 23*120  19.89 0.05  22.6 AZT-33VM
2020-03-26 20:11:20 1.2306   R 14*120  20.07 0.08  22.3 ZTSh
2020-03-26 20:27:39 1.2444   R 35*60    n/d  n/d   20.0 AS-32

the photometry is based on nearby SDSS-DR12 stars
RA DEC               R(Lupton transformations)
167.569191 27.848262 16.015
167.513655 27.832992 16.930
167.510507 27.850424 15.261

We note that coordinates of the OT (Lipunov et al., GCN 27446; Pozanenko 
et al., GCN 27452) coincide with only one XRT source 
( ) found in the error 
localization of GBM/Fermi. Taking into account the XRT source and fading 
OT we suggest the MASTER OT J111012.51+274912.8  is an afterglow GRB 
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