TITLE:   GCN CIRCULAR
NUMBER:  26790
SUBJECT: GRB 200115A: Mondy optical afterglow candidate
DATE:    20/01/16 18:22:00 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

A. Pozanenko (IKI), A. Volnova (IKI),  E. Klunko (ISTP), K. Kamyshnikov 
(HSE), N. Pankov (HSE),  E. Mazaeva (IKI), S. Belkin (IKI)  report   on 
behalf of GRB IKI FuN:

We observed the field of  GRB 200115A (Cenko et al.  GCN 26771) with 
AZT-33IK telescope of Sayan observatory (Mondy) starting on Jan. 15 (UT) 
  11:55:00, i.e. 4.6 minutes after GRB trigger.  Within  BAT 
ground-calculated position (Laha et al. GCN 26780) we   detected the 
only one unidentified object at the coordinates (J2000) 03:45:46.58 
+05:36:36 with uncertainty of 0.5 arcsec in both coordinates. The object 
is absent in SDSS DR12. At this time we cannot confirm variability of 
the object.   We suggest the object is the optical afterglow  of GRB 
200115A. Preliminary photometry of the afterglow candidate is following.

Date       UT start   t-T0       Filter Exp.    OT    Err.  UL(3sigma)
                       (mid, days)        (s)

2020-01-15 11:55:00   0.02455    R      30*120  20.9  0.2   22.1

The photometry is based on the nearby SDSS DR12 stars
SDSS                 R_Lupton
J034551.63+053704.5  17.138  0.016
J034547.51+053555.6  18.214  0.029
J034543.70+053549.4  17.851  0.022