GCN Circular 1415
Subject
GRB020531: Observations with the Chandra X-ray Observatory
Date
2002-06-06T21:59:33Z (22 years ago)
From
George Ricker at MIT <grr@space.mit.edu>
GRB020531: Observations with the Chandra X-ray Observatory
N. Butler, A. Dullighan, P. Ford, G. Monnelly, G. Ricker, R. Vanderspek
(MIT); K. Hurley (U.C.- Berkeley); and D. Lamb (U.Chicago)
on behalf of the Chandra GRB ToO Team and the HETE Science Team
write:
On 5 June, 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). The observations, lasting
20 ksec, spanned the interval 04:00-10:04 UT, 5.15 - 5.40 days after
the burst. The refined IPN error region from Hurley et al. (GCN1407)
was completely contained within the field-of-view of the Chandra
ACIS-I array. The ACIS-I data set for the 20 ksec observation was
received at 22:23 UT, 18.4 hours after the observation began.
Within the refined IPN error region, we detect 10 sources in the
0.5-8 keV band:
# Chandra Name RA DEC dR(s) dD(") Cts
28 CXOU J151459.7-192532 15 14 59.74 -19 25 31.91 0.019 1.36 12
36 CXOU J151459.2-192609 15 14 59.18 -19 26 8.50 0.021 1.36 8
41 CXOU J151503.6-192423 15 15 3.59 -19 24 23.49 0.022 1.36 7
47 CXOU J151514.7-192221 15 15 14.69 -19 22 21.42 0.020 1.37 6
48 CXOU J151455.8-192454 15 14 55.76 -19 24 54.02 0.023 1.36 6
51 CXOU J151513.3-192450 15 15 13.30 -19 24 49.94 0.019 1.36 5
52 CXOU J151501.9-192358 15 15 1.86 -19 23 58.48 0.022 1.36 5
55 CXOU J151457.0-192439 15 14 56.96 -19 24 39.26 0.022 1.36 4
56 CXOU J151514.1-192428 15 15 14.14 -19 24 27.58 0.022 1.37 4
58 CXOU J151508.0-192338 15 15 7.96 -19 23 37.69 0.021 1.36 3
The # column refers to the source's relative ranking (in terms of total
counts) among all the sources detected in the entire ACIS-I field-of-view.
In addition, we detect 3 bright sources just outside of the refined IPN
error region:
0 CXOU J151515.3-192511 15 15 15.31 -19 25 10.71 0.019 1.35 67
5 CXOU J151517.8-192102 15 15 17.80 -19 21 2.20 0.020 1.36 44
15 CXOU J151458.3-192322 15 14 58.34 -19 23 22.32 0.020 1.35 19
For these three bright sources, we note that there are conspicuous
optical counterparts visible in an observation carried out with the
Baade 6.5 meter telescope at the Magellan Observatory on 1 June, 1.19
days after the GRB (see Dulligan et al., GCN1411, for observation
details). The three counterparts for #0, #5, and #15 have approximate
R magnitudes of 20.4, 23.6, and 20.8, respectively.
For both the TAROT A and B source locations (Boer et al., GCN1408), no
X-ray counts are detected in excess of the background rate.
The astrometry was calibrated using three USNO A2 catalog stars with
detectable X-ray emission and lying within the ACIS-I field-of-view.
In the above 2 tables, dR, the uncertainty in RA, and dD, the uncertainty
in DEC, were established by summing the following in quadrature for each
coordinate: the error reported by celldetect, the correlation error
between the X-ray and optical positions, and the error estimate from the
star reference catalog.
We gratefully acknowledge the timely assistance of the personnel at the
Chandra Science Center in the acquisition and preliminary processing of
these data.
This message may be cited.