[vsnet-grb-info 5873] GRB080310, late-time photometry with LBT

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  7523
SUBJECT: GRB080310, late-time photometry with LBT
DATE:    08/03/26 16:22:55 GMT
FROM:    Peter Garnavich at U of Notre Dame  <pgarnavi at nd.edu>

J. Hill (LBTO/UAz), R. Ragazzoni, A. Baruffolo (Padova), and
P. Garnavich (Notre Dame) report:

The Large Binocular Telescope (LBT) observed the position of GRB 080310
(Chornock et al. GCN 7381; Cummings et al., GCN 7382) with the
LBC red and blue cameras between March 19.3 and 19.5 (UT). Twenty
200 sec exposures in the Sloan-r filter were obtained in 1.3"
seeing and with a significant sky background from the Moon.

The combined image shows a faint source present at the position
of the afterglow. From stars calibrated in the SDSS we estimate
the brightness of the source to be r=25.4+/-0.2 mag. This is
consistent with an afterglow  power-law decay index of 2.4 between
2 and 9 days after the burst (Wegner et al., GCN 7423). The
true afterglow decay rate could be steeper if host galaxy light
is contributing to the source flux.

A faint galaxy (r~24) is detected 2.1" southeast of the afterglow and
another is 3.0" to the southwest. For a redshift of 2.43 and a standard
cosmology, the projected distances from the afterglow are 17 kpc and
24 kpc. These galaxies may be the source of the two foreground absorption
line systems observed in the afterglow spectrum (Vreeswijk et al., GCN
7391).


The LBT is an international collaboration among institutions in the
United States, Italy and Germany. The LBT Corporation partners are:
*  The University of Arizona on behalf of the Arizona university system
*  Istituto Nazionale di Astrofisica, Italy
*  LBT Beteiligungsgesellschaft, Germany, representing the Max Planck
Society, the Astrophysical Institute Potsdam, and Heidelberg University
*  The Ohio State University
*  The Research Corporation, on behalf of The University of Notre Dame,
University of Minnesota and University of Virginia

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