[vsnet-grb-info 19237] GRB 170317A: Mondy optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  20924
SUBJECT: GRB 170317A: Mondy optical observations
DATE:    17/03/20 15:19:06 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

E. Mazaeva (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), A. Volnova (IKI) 
  report on behalf of larger GRB follow-up collaboration:

We observed the field of  GRB 170317A (LaPorte et al., GCN  20885) with 
AZT-33IK telescope of Sayan observatory (Mondy) starting on  March, 18 
(UT) 14:57:48. We several images in R-filter.
The optical afterglow (LaPorte et al., GCN 20885; Mazaeva et al., GCN 
20886; Xin et al., GCN 20888; Mao  et al., GCN 20889) is visible in 
stacked images. Preliminary photometry of the afterglow is following

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

2017-03-18 14:57:48  1.23738  R       30*120   23.25  0.22  23.6

The photometry is based on nearby USNO-B.10 stars
Ref.stars
USNO_B1_id   R2

1405-0167631 15.69
1404-0169027 16.03
1405-0167512 16.85
1404-0169128 16.25