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[vsnet-grb-info 454] GRB 021004: Optical Photometry at 2.5 Days
TITLE: GCN GRB OBSERVATION REPORT
NUMBER: 1597
SUBJECT: GRB 021004: Optical Photometry at 2.5 Days
DATE: 02/10/07 19:16:17 GMT
FROM: Stephen Holland at U. of Notre Dame <sholland@nd.edu>
GRB 021004: Optical Photometry at 2.5 Days
S. T. Holland (Notre Dame), J. P. U. Fynbo, M. Weidinger (Aarhus)
M. P. Egholm (NOT), A. Levan (Leicester),
J. Hjorth and H. Pedersen (Copenhagen)
on behalf of a larger collaboration report:
We have obtained deep Rc-band images of the field containing
GRB 021004 using the 2.56-meter Nordic Optical Telescope on La Palma
on the evening of Oct. 6 UT. The optical afterglow of GRB 021004
is visible in our images. Using the comparison star from
Fox et al. (2002, GCN 1564) and the calibration of
Henden (2002, GNC 1583) we find the following preliminary magnitudes:
Date UT t(days) Rc Err
-------------------------------------
Oct. 6 19:57:07 2.327 20.12 0.10
Oct. 6 20:37:26 2.355 20.08 0.01
Oct. 6 21:56:38 2.410 20.16 0.03
Oct. 6 22:08:09 2.418 20.15 0.03
These magnitudes, and those of Holland et al. (2002, GCN 2002),
imply that the optical afterglow faded at a rate a rate of alpha =
-0.9 between 32 and 58 hours after the burst. We note that that the
optical afterglow appears to be fading less slowly than it did between
12 and 17 hours after the burst. A deep Rc image constructed from all
of our data shows no evidence for a host galaxy. A plot of our
preliminary Rc-band light curve is available at
<http://www.nd.edu/~sholland/grb/grb021004/lightcurve2.eps>.
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