TITLE:   GCN CIRCULAR
NUMBER:  8499
SUBJECT: GRB 081028 - PAIRITEL NIR detection
DATE:    08/11/08 23:10:09 GMT
FROM:    Adam Miller at UC Berkeley  <amiller@astro.berkeley.edu>

A. A. Miller, B. E. Cobb, J. S. Bloom, D. A. Perley (UC Berkeley), D. 
Starr (UCB, LCOGT) report:

We observed the optical afterglow of GRB 081028 (Clemens et al., GCN 
8424, Olofsson et al., GCN 8425) with the 1.3-m Peters Automated Infrared 
Imaging Telescope (PAIRITEL). Observations with PAIRITEL began at 11:26:23 
UT on Oct 28, 2008, 11 hours after the GRB trigger. We detect the 
afterglow in a 3727 sec mosaic of 7.8 sec simultaneous exposures in the 
J, H, and Ks filters. Preliminary photometry for the afterglow in these 
mosaics with midtime 12:13:59 Oct 28, 2008 UT yields J = 17.7 +- 0.1, H = 
17.0 +- 0.1, and  Ks = 16.1 +- 0.1 (all magnitudes given in the Vega 
system), calibrated to the 2MASS system. In intermediate mosiacs we find 
that the afterglow gets brighter during our ~1.5 hrs of observations. No 
correction for Galactic extinction (E(B-V) = 0.03; Schlegel et al. 1998) 
has been made to the above reported values.

These measurements indicate that the burst afterglow became 
brighter and redder following the measurements made by Clemens et al. 
(GCN 8424). Schady & Guidorzy (GCN 8431) report an optical brightening of 
the afterglow, consistent with the detected behavior in the NIR, around 
the time of our observations, and further measurements by Clemens et al. 
(GCN 8442) taken roughly 31 hours after the burst trigger show that the 
afterglow is redder than their initial observations.