TITLE:   GCN CIRCULAR
NUMBER:  23947
SUBJECT: GRB 190311A: Mondy optical observations
DATE:    19/03/11 15:49:37 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

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

We observed the field of  GRB 190311A  (Troja et al.  GCN 23946) with 
AZT-33IK telescope of Sayan observatory (Mondy) starting on Mar. 11 (UT) 
  14:39:17.   We  clearly  detected  the candidate in optical afterglow 
(Troja et al.  GCN 23946). Coordinates of the optical transient are 
(J2000) 14:08:15.74 +53:30:03.1 with uncertainty of 0.5 arcsec in both 
coordinates, which correspond to the coordinates obtained in GCN 23946. 
  Preliminary photometry of the afterglow in R-filter is following.

t-T0_mid(d) t-T0_mid(min) R_mag err
0.01111 16.0 19.22 0.11
0.01146 16.5 19.25 0.10
0.01180 17.0 19.50 0.11
0.01215 17.5 19.23 0.10
0.01250 18.0 19.47 0.12
0.01285 18.5 19.46 0.10
0.01348 19.4 19.50 0.08
0.01417 20.4 19.62 0.08
0.01487 21.4 19.55 0.09
0.01556 22.4 19.58 0.08
0.01626 23.4 19.56 0.09
0.01695 24.4 19.62 0.09
0.01765 25.4 19.79 0.10
0.01875 27.0 19.83 0.06
0.02014 29.0 19.83 0.06

Photometry is based on the SDSS-DR12 stars (Lupton transformations)
SDSS-DR12_id	        R
J140819.68+532900.1	17.09
J140818.11+532934.7	15.19
J140809.64+533055.9	16.97
J140807.35+533116.9	16.11

The optical transient is fading and we can confirm the optical afterglow 
of  GRB 190311A.