[vsnet-grb-info 20219] GRB 180103A: LCO Sutherland 1-m telescope observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22315
SUBJECT: GRB 180103A: LCO Sutherland 1-m telescope observations
DATE:    18/01/10 18:59:27 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi at fe.infn.it>

C. Guidorzi (U. Ferrara), S. Kobayashi (LJMU), C.G. Mundell (U. Bath), A. Gomboc (U. Nova Gorica), I.A. Steele (LJMU) on behalf of a large collaboration report:

We observed the field of Swift GRB180103A (Beardmore et al. GCN 22305) on January 06, from 22:12 to 22:35 UT (3.9 days post burst) with one of the 1-m LCO telescopes in Sutherland in the SDSS-I filter. Within the XRT error circle of the source mentioned by Melandri et al. (GCN 22308) we see two sources, for which we measure the following magnitudes:

RA(J2000.0)  DEC(J2000.0)     Exposure       Filter       Magnitude (AB)
                                (s)
-------------------------------------------------------------------------
10:38:24.24  -53:33:17.3     9x120          SDSS-I        19.68 +- 0.07
10:38:24.64  -53:33:21.3     9x120          SDSS-I        19.19 +- 0.05
-------------------------------------------------------------------------

as calibrated against USNO UCAC4 field stars. Although we presently cannot make any statement about possible variability, the crowded field suggests that both sources are likely to be unrelated to the GRB. No other sources down to i<20.8 mag are seen within the same XRT error circle.