[vsnet-grb-info 9933] GRB 101030A: GROND optical/NIR afterglow candidate

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  11391
SUBJECT: GRB 101030A: GROND optical/NIR afterglow candidate
DATE:    10/10/31 19:43:07 GMT
FROM:    Thomas Kruehler at MPE/MPI  <kruehler at mpe.mpg.de>

T. Kruehler, P. Schady, and J. Greiner (all MPE Garching)  report on
behalf of the GROND team:

GROND (Greiner et al. 2008, PASP 120, 405), mounted at the 2.2m MPG/ESO
telescope at LaSilla Observatory (Chile), performed automated follow-up
observations of GRB 101030A (Melandri et al., GCN #11386) as soon as the
field rose above the pointing constraints of the telescope. Imaging was
performed simultaneously in g'r'i'z'JHK starting at 08:12 UT on
2010-10-31, which is 16.3 h after the burst. Inside the enhanced XRT error
circle (Evans et al., GCN# 11387), GROND detects a single object at:

RA (J2000)= 11:05:31.68
Dec (J2000)= -16:22:41.1

with uncertainties of 0.3" in each coordinate.

Preliminary AB magnitudes and upper limits in stacked images of 15 min
integration time in each g'r'i'z' and 20 min in JHK at a midtime of 08:46
UT are:

g' = 22.9 +- 0.3
r' = 22.4 +- 0.1
i' = 22.0 +- 0.1
z' = 22.1 +- 0.2
J = 21.7 +- 0.4
H > 21.2
K > 20.5

which have been tied to SDSS and 2MASS field stars. No statement about
variability can be made at this point. No source is reported at this
location in the SDSS, which is somewhat deeper than the object's
magnitudes, and hence we suggest this source is the optical/NIR afterglow
of GRB101030A.

We thank the ESO staff at LaSilla observatory, and in particular P. Arias,
for their excellent support and assistance with the observations.