GCN Circular 2597
Subject
GRB040511: Candidate optical/NIR afterglow
Date
2004-05-14T01:51:23Z (20 years ago)
From
Derek Fox at CIT <derekfox@astro.caltech.edu>
D.B. Fox, E. Berger and D. Moon (Caltech), with K. von Braun and
B. Lee (Carnegie), report:
"We have imaged the SXC localization region for GRB040511 (Dulligan et
al., GCN 2588) in the J-band with the Dupont telescope + WIRC imager
at Las Campanas Observatory, on two occasions. Our first-night
imaging consists of 21 minutes' exposure at mean epoch May 12.05 UT
(12.2 hours post-burst) in 1" seeing; our second-night imaging
consists of 15 minutes' exposure at mean epoch May 13.35 UT (43.4
hours post-burst) in 0.75" seeing.
PSF-matched image subtraction of the combined images from these two
nights reveals a single source within the SXC region that fades
significantly between the two epochs, from J~19.0 mag to J~20.9 mag as
referenced to 2MASS photometry of the field. Since the source is also
observed to fade (by ~1.3 mag) in the contemporaneous (t+11 hour and
t+36 hour, respectively) R-band imaging of Morrell et al. (GCN 2594)
and Chen et al. (GCN 2591), we conclude that it is a likely afterglow
candidate. The source coordinates are:
RA 14:47:49.33, Dec -44:14:21.8 (J2000)
as referenced to 2MASS catalog astrometry; the uncertainty in this
position is < 0.5". The image-pixel coordinate position of the
candidate on the first-epoch imaging of Chen et al. (see
http://www.graasp.org/, "DATA" section, file "grb040511_R1.fits") is
X=1214.6, Y=1463.8.
The authors would like to express their gratitude to the the Carnegie
Supernova Program for this allocation of time, and to the GRAASP
collaboration for the public release of their data in FITS format.