TITLE:   GCN CIRCULAR
NUMBER:  11743
SUBJECT: GRB 110213B: GROND observations of the optical/NIR afterglow
DATE:    11/02/16 19:35:01 GMT
FROM:    Jonny Elliott at MPE/GROND  <jonnyelliott@mpe.mpg.de>

J. Elliott (MPE Garching), A. Nicuesa Guelbenzu (TLS Tautenburg), T.
Kruehler and J. Greiner (both MPE Garching) report on behalf of the GROND
team:

We observed the afterglow (Cenko et al., GCNs #11732, 11736) of GRB
110213B (Negoro et al., GCN #11716 & Morii et al., GCN #11720)
simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120,
405) mounted at the 2.2m MPI/ESO telescope at La Silla Observatory
(Chile).

Observations started at 01:22 UT on 16.02.2011, 2.45 days after the GRB
trigger and were performed at high airmass.

Based on a stacked image with exposure time of 460 s, we estimate a
preliminary r' band magnitude of r' = 20.8 +/- 0.1 calibrated against SDSS
field stars. This implies a fading with respect to the earlier measurement
of Cenko et al. (#GCN 11732). In addition, the SED of the object is
consistent with a power-law, and hence we confirm the source as the
optical afterglow of GRB 110213B.