TITLE:   GCN CIRCULAR
NUMBER:  27257
SUBJECT: GRB 200227A: Mondy optical upper limit
DATE:    20/02/28 14:30:50 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Belkin (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), E. Mazaeva (IKI), 
A. Volnova (IKI) report on behalf of IKI-GRB-FuN:

We observed the field of GRB 200227A (Fermi GBM Team et al., GCN 27233; 
Laha et al., GCN 27234) with AZT-33IK telescope of Sayan observatory 
(Mondy) starting on Feb. 27 (UT) 12:47:07.  Within enhanced Swift-XRT 
position of afterglow (Beardmore et al., GCN 27243) we did not detect 
optical
  afterglow in agreement with previously reported non-detection (Oeda et 
al., GCN 27236;  Oates et al., GCN 27244). Preliminary photometry of the 
field is following.

Date UT start,      t-T0    Filter Exp.   OT UL(3sigma)
                      (mid, days)    (s)
2020-02-27 12:47:07 0.24582  R   27*120 n/d 23.2

Photometry is based on the SDSS-DR12 nearby stars (Lupton’s transformation)
SDSS-DR12_id        R(Lupton)
J034542.04+092727.3 18.56
J034546.87+092955.7 17.19
J034534.13+092646.2 17.32