[vsnet-grb-info 14421] GRB 140103A: AAO optical afterglow candidate

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15735
SUBJECT: GRB 140103A: AAO optical afterglow candidate
DATE:    14/01/14 20:23:50 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

A. Volnova (IKI), R. Inasaridze (AAO), G. Inasaridze (AAO), V.
Zhuzhunadze (AAO), Yu. Krugly (IA KhNU), I. Molotov (KIAM), A. Pozanenko 
(IKI) report on behalf of larger GRB follow-up collaboration:

We observed the optical counterpart of the Swift GRB 140103A (Mangano et 
al., GCN 15656) with AS-32 (0.7m) telescope of Abastumani Observatory on 
Jan. 3 and 4. We obtained several unfiltered images of 120 s exposure 
during each observational set. In the refined XRT position (Mangano, GCN 
15666) we do not detect any object in stacked images. However we found a 
fading object which is not present in SDSS catalog. The coordinates of 
the obsjet is (J2000)   RA=15 28 20.73, Dec = +37 45 28.8 with 
uncertainity of  0.3" in each coordinate. The position of the fading 
object is 5.2" from the refined XRT position (Mangano, GCN 15666). Due 
to fading nature of the new object we suggest it as an afterglow of the 
GRB 140103A.

Details of the photometry   is following:

Date        T_start   t-t0,     Filter  Exp.,    OT   err.
               (UT)    mid, d            s
2014-01-03  01:21:18  0.03953  None     5*120  21.14  0.12
2014-01-03  01:34:40  0.05345  None    10*120  21.35  0.12
2014-01-03  02:01:21  0.07662  None    15*120  21.41  0.11
2014-01-04  01:47:48  1.08483  None    34*120  >22.3  (3 sigma)

The photometry is based on SDSS DR9 stars and gri -> R transformations 
(Lupton):

N  SDSS_id              R(Lupton)
1  J152814.09+374706.3  18.20
2  J152819.83+374538.8  15.61

Finding chart and a light curve of the afterglow can be found in
http://grb.rssi.ru/GRB140103A/grb140103A_chart.png
and
http://grb.rssi.ru/GRB140103A/grb140103A_lc.PNG