[vsnet-grb-info 16490] GRB 150428A: Danish1.56m optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17771
SUBJECT: GRB 150428A: Danish1.56m optical observations
DATE:    15/04/28 07:29:12 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu at nao.cas.cn>

M. I. Andersen (NBI/StarPlan), D. Xu (NAOC/CAS), M. Kuffmeier (StarPlan), and D. Evans (Keele U.) report on behalf of a larger collaboration:

We observed the field of GRB 150428A (Page et al., GCN 17765) using the Danish 1.56m telescope located at La Silla, Chile. Observations started at 01:56:33 UT on 2015-04-28 (i.e., 0.43 hr post-burst) and 12x180s R-band images were obtained.

We marginally detect a source in the stacked image at coordinates

R.A. = 12:34:09.227
Dec. = +6:57:14.07

Error Radius: ~ 1 arcsec,

consistent with the enhanced XRT position (Osborne et al., GCN 17768). Preliminary reduction shows that the source has m(R) = 22.50 +/- 0.43 mag at a median time of 0.887 hr post-burst, calibrated with two nearby SDSS stars. It could be the afterglow of the GRB.

We also detect the source reported by GROND (Knust et al., GCN 17767). It is extended in the northwest-southeast direction. Its position is not consistent with the present enhanced XRT position, as noted by P60 (Perley, GCN 17769).