[vsnet-grb-info 17468] GRB 160119A: NOT and GTC afterglow candidate

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  18895
SUBJECT: GRB 160119A: NOT and GTC afterglow candidate
DATE:    16/01/19 05:06:13 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani at dark-cosmology.dk>

D. Malesani (DARK/NBI), A. de Ugarte Postigo (IAA-CSIC and DARK/NBI), D. 
Xu (NAO/CAS), C.E. Martinez-Vazquez (IAC-ULL), A. Tejero (GTC), S. Geier 
(GTC), C.C. Thoene (IAA-CSIC), P. Jakobsson (Univ. Iceland) report on 
behalf of a larger collaboration.

We observed the field of GRB 160119A (Marshall et al., GCN 18893) with 
the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. 
Observations were carried out in the SDSS r and i bands, starting on 
2015 Jan 19.151 UT (31 min after the GRB trigger).

We also observed the same field using the Gran Telescopio Canarias 
(GTC), equipped with OSIRIS, starting on Jan 19.164 UT (50 min after the 
GRB trigger), also in the r and i bands.

Compatible with the current XRT localization (3.6" radius, SPER-based; 
http://www.swift.ac.uk/xrt_positions/), we detect a single, faint 
optical source, at coordinates (J2000):

RA = 14:07:41.35
Dec = +20:27:40.1

with an uncertainty of <0.5".

Using nearby stars from the SDSS catalog, we measure from the NOT image 
a magnitude r = 22.75 +- 0.15 (AB). This magnitude measurement is 
affected by the extended glare of a nearby bright star, making 
background subtraction less accurate than normal. This object is also 
seen, faintly, in the short GTC images (30-60 s exposure).

The object seems marginally brighter than the SDSS detection limit. 
However, despite ~20 min time difference between the NOT and GTC data, 
we do not measure obvious variability between the two epochs, as it is 
common among GRB afterglows close to the trigger. Further observations 
will be necessary to ascertain the relation of this object with the GRB.