[vsnet-grb-info 9613] GRB 100802A: further NOT observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  11082
SUBJECT: GRB 100802A: further NOT observation
DATE:    10/08/12 10:37:13 GMT
FROM:    Dong Xu at DARK,NBI  <dong at astro.ku.dk>

Nis B. Andreasen, Louise Dyregaard Nielsen, Christopher Groenbech,
Simone J. Jakobsen, Jonatan Selsing, Lasse Oedegaard (Niels Bohr
Inst.), Johan P.U. Fynbo, Daniele Malesani (DARK/NBI), Dong Xu
(Weizmann Inst.), and Pall Jakobsson (Univ. Iceland), report on behalf
of a larger collaboration:

We observed the field of GRB 100802A (Troja et al., GCN 11031, Siegel
& Troja, GCN 11032) with the NOT equipped with ALFOSC. Observations
were carried out with mean time Aug 11.10 UT (212.7 hr after the GRB).

The object seen in our early-time NOT image (Xu et al., GCN 11042) is
barely detected in the new stacked image, and has decayed by 1.3 +/-
0.4 mag between the two epochs.

We note that the NOT object is slightly offset (by ~1.1" W) with
respect to the UVOT position (GCN 11032; also confirmed by P60
imaging; B. Cenko, priv. comm.). Coupled to the slow decay, this may
indicate the presence of an underlying constant source of light, which
could be the host galaxy or a foreground, unrelated object.

An image showing the two epochs is available at the following URL:

http://www.astro.ku.dk/~malesani/GRB/100802A/GRB100802A_epoch2.jpg

Given the relative brightness of the underlying source (R ~ 23.7), we
encourage further photometric and spectroscopic observations.