Skip to main content
Testing. You are viewing the public testing version of GCN. For the production version, go to
Introducing Einstein Probe, Astro Flavored Markdown, and Notices Schema v4.0.0. See news and announcements

GCN Circular 3672

GRB 050724: Optical imaging/astrometry
2005-07-25T01:09:43Z (19 years ago)
Josh Bloom at Harvard/CFA <>
J. S. Bloom (UC Berkeley), A. Dupree (Smithsonian Astrophysical
Observatory), H-W. Chen (MIT), & J. X. Prochaska (UC Santa Cruz) report:

"Comparison of the 2MASS catalog with a short exposure with the
unfiltered MIKE (Magellan II/Clay) guider CCD camera beginning on
2005-07-24 23:25:25 UTC shows faint sources near the XRT localizations
(GCNs #3665 & #3669). We find the following positions (systematic
error relative to the ICRS is 0.2" in both RA and DEC):

 A  16:24:44.964 -27:32:23.21 J2000 Source 1 in #3669 error circle
 B  16:24:44.912 -27:32:32.73 J2000 Source 1 in #3665 error circle,
 				    noted by Antonelli et al. #3666
 C  16:24:45.303 -27:32:34.67 J2000 Source 2 in #3665 error circle
 D  16:24:44.398 -27:32:26.85 J2000 Bright galaxy to the West of
			            XRT error circles

Source D appears to be an extended galaxy and, while formally excluded
by the 90% confidence regions of the various positions reported for
the X-ray afterglow, is of interest nonetheless (especially given what
appears to be an emerging trend of low-redshift galaxies associated
with short bursts)."

A finding chart may be found at:

Please email JSB if you would like to make use of the guider FITS image.

This message may be cited.

[GCN OPS NOTE 924jul05): Per author's request, hanged "astronomy" to
"astrometry" in the Subject.]
Looking for U.S. government information and services? Visit