[AAVSO-HEN] GRB 080120: GROND confirmation of the optical afterglow

[grb at aavso.org]

The following is a GCN Circular circulated via the AAVSO network.
For an archive and more information on circulars visit:
http://lheawww.gsfc.nasa.gov/docs/gamcosray/legr/bacodine/gcn3_archive.html

TITLE:   GCN CIRCULAR
NUMBER:  7202
SUBJECT: GRB 080120: GROND confirmation of the optical afterglow
DATE:    08/01/22 09:10:16 GMT
FROM:    Thomas Kruehler at MPE/MPI  <kruehler at mpe.mpg.de>

T. Kruehler, J. Greiner, S. McBreen, S. Loew, A. Kuepcue-Yoldas, C. Clemens, A. Yoldas 
(all MPE Garching) report on behalf of the GROND team:

We observed the field of the INTEGRAL burst GRB 080120 (Mereghetti et al. 2008, GCN #7194) with the 2.2 m MPI/ESO telescope equipped with the multi-channel imager GROND. 
Observations started at 07:04 UTC on the 22nd of January at an airmass of 2.5 and seeing around 1.0". 

The optical/NIR source (Kruehler et al. 2008, GCN #7197, P. Schady et al. 2008, GCN #7198) inside the XRT-error circle (Sbarufatti et al. 2008, GCN #7195) is still detected, and clearly fading. Fitting a power-law to the two epochs yields a slope around 1.5.

A finding chart will be posted at: www.mpe.mpg.de/~jcg/grb080120.html