[vsnet-grb-info 15242] GRB140706A: GROND detection of the Optical/NIR afterglow

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16534
SUBJECT: GRB140706A: GROND detection of the Optical/NIR afterglow
DATE:    14/07/07 10:05:11 GMT
FROM:    Patricia Schady at MPE/Swift  <pschady at mpe.mpg.de>

P. Schady (MPE Garching), S. Klose (TLS Tautenburg) and J.Greiner (MPE Garching) report on behalf of the GROND team:

We observed the field of GRB 140706A (Swift-603587; Marshall et al., GCN #16531) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla Observatory (Chile).

Observations started at 09:01UT on 7th-July, 13.5 hours after the GRB trigger, and are continuing. They were performed at an average seeing of 1.3” and at an average airmass of 1.5.

We found a single point source within the 2.2" Swift-XRT enhanced error circle reported by Beardmore et al. (GCN #16532) consistent with the UVOT position (Marshall et al., GCN #16531).

Based on the first 8 min exposure, we estimate preliminary magnitudes (all in AB system) of

g' = 22.4 +/- 0.1 mag,
r' = 22.1 +/- 0.1 mag,
i' = 21.9 +/- 0.1 mag,
z' = 21.5 +/- 0.1 mag,
J > 20.9 mag,
H > 20.3 mag, and
K > 18.8 mag.

Given magnitudes are calibrated against GROND zeropoints as well as 2MASS field stars and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.02 mag in the direction of the burst (Schlegel et al. 1998).