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GCN Circular 7010

Subject
GRB 071003: Infrared Photometry with Keck Adaptive Optics
Date
2007-10-26T22:51:07Z (17 years ago)
From
Daniel Perley at U.C. Berkeley <dperley@astro.berkeley.edu>
L. K. Pollack (UC Santa Cruz), M. A. van Dam (WM Keck Observatory), D. 
Le Mignant (WM Keck Observatory, UC Santa Cruz), E. M. Johansson (WM 
Keck Observatory), D. A. Perley (UC Berkeley), and J. S. Bloom (UC 
Berkeley) report:

On October 19 at UT 05:14:04 we observed the afterglow of GRB 071003 
(Schady et al., GCN 6837; Li, GCN 6838; Cenko et al. GCN 6839) with the 
NIRC2 narrow-field camera (0.01 arcsec/pixel) on Keck II using natural 
guide star adaptive optics (NGS AO).  We took 15 exposures, each of 60 
seconds and 2 coadds, resulting in a total integration time of 30 
minutes.  The natural guide star is located 6.5 arcseconds west of the 
afterglow position, and has R=11 mag.

The K=12.011 +/- 0.024 mag 2MASS star located 7.8 arcseconds east of the 
afterglow position was used as a photometric calibrator. Assuming no 
changes in the AO-corrected PSF over these distances, we measure the 
afterglow to have K' = 21.58 +/- 0.03.  We find no host galaxy at the 
position of the afterglow.

We detect the galaxy previously reported by Perley et al. (GCN 6874) at 
a position 2.07 arcseconds southwest of the afterglow position. 
Photometry on this extended object is difficult in the presence of the 
bright nearby star; however, we measure the galaxy to have an 
approximate brightness of K'=19.1 +/- 0.1 mags within an aperture of a 
0.5 arcsecond radius.

An image of the observations has been posted to:
http://www.ucolick.org/~pollack/071003.jpg .

We thank the Keck staff for performing these observations.  In 
particular, we would like to acknowledge the help of Al Conrad.
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