[vsnet-grb-info 522] GRB021004, late-time optical observations

[GCN Circulars <gcncirc@lheawww.gsfc.nasa.gov>]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  1661
SUBJECT: GRB021004, late-time optical observations
DATE:    02/10/29 01:12:31 GMT
FROM:    Peter Garnavich at U of Notre Dame  <pgarnavi@miranda.phys.nd.edu>

P. Garnavich and J. Quinn (Notre Dame)

We observed the optical afterglow of GRB 021004
(Fox et al. GCN 1564) with the 1.8m Vatican Advanced
Technology Telescope beginning 2002 Oct 26.25 (UT).
Seven, 10 minute exposures in the R band were combined
and an unresolved source was detected within 0.2"
of the afterglow position. Assuming the star at
00:26:51.44 18:54:36.3 (2000) has a magnitude of
R=17.142 (Henden GCN 1630) we find the afterglow
brightness to be R=23.39+/-0.12. Combining the
Williams, Lindsay, & Milne (GCN 1652) observation with
the VATT image provides a power-law decay index of -1.7
between one and three weeks after the burst. This is
significantly steeper than the "average" decay index
between 0.4 and 3 days after the burst (Holland et al.
GCN 1597) and may indicate a final break in the light
curve. Although, the odd variability of GRB 021004 makes 
this conclusion uncertain. 

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