GCN Circular 1426
Subject
GRB020531: Second epoch Chandra observations
Date
2002-06-11T22:11:28Z (22 years ago)
From
Roland Vanderspek at MIT <roland@space.mit.edu>
GRB020531: Results of a Second Epoch Observation with the Chandra X-ray
Observatory
N. Butler, A. Dullighan, P. Ford, G. Monnelly, G. Ricker, R. Vanderspek
(MIT); and D. Lamb (U.Chicago)
on behalf of the Chandra GRB ToO Team and the HETE Science Team
write:
Between 10 June 20:59 UT to 11 June 00:13 UT, the Chandra Observatory
targeted the field of the short duration gamma-ray burst GRB020531 that
was initially localized by the HETE satellite (Ricker et al., GCN1399).
This observation began 10.86 days after the GRB. This was a 10 ksec
observation with ACIS-I, following up the 20 ksec observation
performed with ACIS-I on 5 June (Butler et al., GCN 1415).
Of the 10 sources reported in GCN1415 lying within the refined IPN
error region (Hurley et al. GCN1407), only one source declined in
brightness with a significance greater than 2 sigma:
# Chandra Name RA DEC E1 Cnts E2 Cnts
48 CXOU J151455.8-192454 15 14 55.76 -19 24 54.02 6 ~0
This source faded in a manner that is consistent with the power-law behavior
that is characteristic of (long duration) gamma-ray burst afterglows. (A
power law index of -1.3 implies a decline in brightness by a factor of 2.6
between our 1st and 2nd epoch observations.)
We note that source #0 declined in brightness with a significance of 2.0
sigma, but remained ~2x brighter than would be expected based on a t^-1.3
extrapolation.
0 CXOU J151515.3-192511 15 15 15.31 -19 25 10.71 67 21
Here "E1 Cnts" and "E2 Cnts" denote, respectively, the epoch 1 and epoch 2
net counts for the source.
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