[vsnet-grb-info 14233] GRB 131128A: GROND observations of the afterglow

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15547
SUBJECT: GRB 131128A: GROND observations of the afterglow
DATE:    13/11/29 14:41:34 GMT
FROM:    Sylvio Klose at TLS Tautenburg  <klose at tls-tautenburg.de>

S. Schmidl, S. Klose, A. Nicuesa Guelbenzu (TLS Tautenburg), and J. 
Greiner (MPE Garching) report:

We observed the field of GRB 131128A (Swift trigger 579683; Sonbas et al., 
GCN 15533) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, 
PASP 120, 405) mounted at the 2.2m MPG telescope at ESO La Silla 
Observatory (Chile).

Observations started at 00:27 UT on November 29, about 9.5 hrs after the 
GRB trigger and were performed under moderate seeing conditions (1.6") and 
moderate airmass (2.3). For the optical afterglow discovered by Xu et al. 
(GCN 15535, 15537) we measure

RA, DEC (J2000) = 23:41:13.795, +31:18:22.32 (+/- 0.2"),

and

r'(AB) = 22.6 +/- 0.1,

calibrated against SDSS field stars (mean time 01:12 UT). Photometry in 
the other GROND bands is affected by a bright star very close to the 
afterglow. It might be improved once second-epoch data are obtained.