TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  2741
SUBJECT: GRB040924:  Optical afterglow properties
DATE:    04/09/25 05:31:19 GMT
FROM:    Derek Fox at CIT  <derekfox@astro.caltech.edu>

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:
 <http://www.astro.caltech.edu/~derekfox/grb040924/>."