TITLE:   GCN CIRCULAR
NUMBER:  26519
SUBJECT: GRB 191220A: SAO RAS possible OT detection
DATE:    19/12/20 17:32:49 GMT
FROM:    Moskvitin Alexander at SAO RAS  <mosk@sao.ru>

A. Moskvitin on behalf of larger GRB follow-up team report.

We observed the field of the GRB 191220A with the SAO RAS
Zeiss-1000 telescope equipped with the MMPP (Multi-Mode
Photometer-Polarimeter). The observations were started since
1.419 hours after the trigger (Laha et al., GCNC #26516).
We obtained 8 x 300 sec. frames in Rc band (14:54:44 -- 15:39:44 UT).

Within the enhanced XRT error circle (Evans, GCNC #26515)
we detect single object, possible OT, with the coordinates
R. A. = 18:45:31.10, Decl. = +26:39:20.8, +/- 0".3, Epoch = 2000.
ftp://ftp.sao.ru/pub/grb/GRB191220A/GRB_possibleOT.jpg

Preliminary brightness of the object is R = 20.46 +/- 0.08
(T_mid - T0 = 1.794 h). Photometry were made against the R2
magnitudes of nearby USNO-B1 stars.