TITLE:   GCN CIRCULAR
NUMBER:  19483
SUBJECT: GRB 160601A: Mondy optical observations
DATE:    16/06/01 19:54:08 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

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

We observed the field of the Swift  GRB 160601A (Kocevski et al., GCN 
19478) with AZT-33IK telescope of Sayan observatory (Mondy)  starting on 
June, 01 (UT) 15:00:41.  We obtained several images in R-filter under 
good weather conditions and FWHM of 1.5 arcsec. Using only part of 
images available we marginally detect (S/N ~2) a source at the edge of 
Swift-XRT position (Kocevski et al., GCN  19478).   Coordinates of the 
source are (J2000) 15:39:44.43 +64:32:19.3 with uncertainty of 1 arcsec. 
Preliminary photometry  of  the source is R~22.3, and details of 
observations are   following

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

2016-06-01  15:00:41   0.03026  R      16*60  22.3   21.8

Photometry is based on nearby SDSS-DR9 stars, Lupton transformations into R:
SDSS-DR9_id            R(Lupton)
J153959.67+643325.7    16.72
J153956.37+643102.2    17.00
J153931.88+643247.0    17.02
J153927.50+643304.3    19.23
J153942.70+643016.4    16.27

We will update the results after all the data will be available.