Skip to main content
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circular 2741

GRB040924: Optical afterglow properties
2004-09-25T05:31:19Z (20 years ago)
Derek Fox at CIT <>
D.B. Fox (Caltech) reports on behalf of a larger collaboration:

"Further analysis of our Robotic P60 observations of the candidate
optical afterglow of GRB040924 (GCNs 2734, 2735) reveals that the
candidate afterglow fades by 0.87 +/- 0.08 mag from our first exposure
(mean epoch 12:07:57 UT) to our last exposure (mean epoch 12:42:09
UT).  Referenced to the time of the burst this corresponds to a decay
with power-law index alpha approximately equal to -0.7.

The coordinates of the candidate referenced to the GSC-2.2 are:

    RA 02:06:22.55, Dec +16:06:48.8 (J2000)

with coordinate uncertainties of approximately 0.2".  

Photometric calibration of the data against the F-emulsion magnitudes
of the GSC-2.2 yields an R-band magnitude of the candidate at our
first epoch (945 sec after the burst) of R=18.0 mag.

Images and a finding chart for the candidate may be found at:
Looking for U.S. government information and services? Visit