[vsnet-grb-info 13777] GRB 130812A: GROND upper limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15091
SUBJECT: GRB 130812A: GROND upper limits
DATE:    13/08/13 13:19:03 GMT
FROM:    Jochen Greiner at MPI  <jcg at mpe.mpg.de>

K. Varela (MPE Garching), D.A. Kann (TLS Tautenburg), J. Greiner 
(MPE Garching) report on behalf of the GROND team:

We observed the field of GRB 130812A (Swift trigger 566228; 
D'Elia et al. 2013, GCN #15088) simultaneously in g'r'i'z'JHK with 
GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 
2.2 m MPG/ESO telescope at La Silla Observatory (Chile).

Observations started at 10:13 UT on 13 Aug. 2013, 11.8 hrs after the 
GRB trigger. They were performed at an average seeing of 2.5" and at 
an average airmass of 1.4.

In 212 sec exposure in g'r'i'z' and 360 sec exposure in JHK 
we do not detect a source within the 1.8 arcsec Swift-XRT error 
circle reported by Evans et al. (2013; GCN #15089) down to
(all in the AB system)

g' > 22.4,

r' > 22.6,

i' > 21.9,

z' > 21.7,

J > 20.3,

H > 19.4 and

K > 18.8

The given limits are derived based on calibrating the images against 
GROND zeropoints and 2MASS field stars and are not corrected for the 
Galactic foreground extinction corresponding to a reddening of 
E_(B-V)= 0.23 in the direction of the burst (Schlegel et al. 1998).