[vsnet-grb-info 17725] GRB 160310A: NOT optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  19164
SUBJECT: GRB 160310A: NOT optical observations
DATE:    16/03/10 21:55:00 GMT
FROM:    Thomas Kruehler at MPE Garching  <kruehler at mpe.mpg.de>

T. Kruehler (MPE Garching), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI),
D. Malesani (DARK/NBI), and T. Kuutma (NOT) report on behalf of a
larger collaboration:

We observed the field of GRB 160310A (Vianello et al., GCN #19158,
Toelge & Hui, GCN #19161) with the NOT equipped with ALFOSC.
Imaging in the i-band filter started at 20:40:57 UT on
2016-03-10, 20.3 hr after the GRB trigger.

In a combined image of 5x120 s exposure time, we detect a single
source in the XRT error circle (Gibson et al. GCN#19162) at a
position of

RA (J2000.0) = 06:35:17.33
Dec. (J2000.0) = -07:12:56.0

with an uncertainty of 0".5 in each coordinate.

Calibrating our image against I-band magnitudes from field stars
of the USNO-B1 catalog, we measure a preliminary brightness of

I = 21.4 +- 0.2 mag

not corrected for the expected foreground extinction corresponding
to a reddening of E_B-V = 0.486 mag (Schlafly & Finkbeiner 2011)

The field is relatively crowded, and chance coincidences in the 5.1"
error circle are not unlikely. No statement about possible variability
can be made at this point.