[AAVSO-HEN] GRB 080905A: optical afterglow

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TITLE:   GCN CIRCULAR
NUMBER:  8195
SUBJECT: GRB 080905A: optical afterglow
DATE:    08/09/07 10:35:30 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani at astro.ku.dk>

A. de Ugarte Postigo (ESO), D. Malesani (DARK/NBI), A. J. Levan (Univ. 
Warwick), J. Hjorth (DARK/NBI), N. R. Tanvir (Univ. Leicester), report 
on behalf of a larger collaboration:

We observed again the field of the short GRB 080905A (Pagani et al., GCN 
8180) with the ESO VLT equipped with FORS2. R-band observations were 
carried out starting on 2008 Sep 7.004 UT (1.50 days after the GRB) and 
the total exposure time was 40 minutes.

The object located inside the XRT error circle visible in our early VLT 
images (Malesani et al., GCN 8190) has clearly faded between the two 
observations, and is thus likely the optical afterglow of GRB 080905A. 
We note that this object is located outside the revised 2.2"-radius 
(90%) UVOT-enhanced XRT error circle (distance from center 4.6"), as 
provided at http://www.swift.ac.uk/xrt_positions/index.php (value of Sep 
7.4 UT).

In our second epoch image, which is deeper and has a better seeing 
(~0.9"), we also note the presence of a bright extended object, possibly 
a spiral galaxy, about 9" S, 3" E of the afterglow (partially covered by 
foreground stars).

Finding charts can be found at

http://www.astro.ku.dk/~malesani/GRB/080905A/#epoch2

We acknowledge significant support from the ESO observing staff at 
Paranal, in particular Elena Mason, Anders Pino and Swetlana Hubrig.