GCN Circular 2716
Subject
GRB040912(=H3557): Observations with the Chandra X-ray Observatory
Date
2004-09-16T18:21:46Z (20 years ago)
From
Roland Vanderspek at MIT <roland@space.mit.edu>
GRB040912(=H3557): Observations with the Chandra X-ray Observatory
N. Butler, P. Ford, G. Ricker, R. Vanderspek, J. Villasenor,
P. Csatorday (MIT); D. Lamb (U. Chicago); and J.G. Jernigan (UCB), on
behalf of a Chandra GRB ToO Team,
write:
On 15 September 2004, the Chandra Observatory targeted the field of
GRB040912, an X-ray flash localized by the HETE satellite (=H3557;
Butler et al, GCN 2701). The 20 ksec observation spanned the
interval 21:57 UT on 15 September to 3:48 UT on 16 September, 3.32 - 3.57
days after the burst. The WXM error circle from Butler et al. was completely
contained within the field-of-view of the Chandra ACIS-I array.
Within the WXM error region, we detect 22 sources with more than 6
source counts in the 0.5-8 keV band:
# Chandra Name RA DEC Cts HR
1 CXOU J235631.0-005946 23 56 30.96 -0 59 46.1 55 -0.5
2 CXOU J235700.0-010009 23 56 59.96 -1 0 9.7 40 -0.3
3 CXOU J235712.2-005942 23 57 12.17 -0 59 42.1 33 -0.3
4 CXOU J235642.9-005520 23 56 42.91 -0 55 20.4 32 -0.7
5 CXOU J235645.7-005655 23 56 46.71 -0 56 54.9 32 -0.3
6 CXOU J235707.6-005713 23 57 7.57 -0 57 12.6 31 0.8
7 CXOU J235716.4-010109 23 57 16.37 -1 1 8.7 27 -0.2
8 CXOU J235639.1-005556 23 56 39.10 -0 55 55.8 20 0.9
9 CXOU J235651.2-005513 23 56 51.17 -0 55 12.5 17 -0.3
10 CXOU J235636.7-005431 23 56 36.74 -0 54 31.2 15 -0.6
11 CXOU J235711.1-005637 23 57 11.12 -0 56 37.1 12 -0.2
12 CXOU J235637.3-010160 23 56 37.26 -1 1 59.9 12 -0.6
13 CXOU J235656.4-005839 23 56 56.42 -0 58 39.2 11 -0.1
14 CXOU J235700.1-005713 23 57 0.09 -0 57 12.6 11 -1.0
15 CXOU J235659.8-005903 23 56 59.83 -0 59 2.8 10 -0.6
16 CXOU J235649.1-010344 23 56 49.07 -1 3 44.2 9 0.4
17 CXOU J235700.4-010018 23 57 0.36 -1 0 17.6 9 -0.7
18 CXOU J235646.4_005621 23 56 46.45 -0 56 21.4 8 1.1
19 CXOU J235647.0-010045 23 56 46.97 -1 0 45.1 8 0.0
20 CXOU J235648.8-010319 23 56 48.81 -1 3 18.6 8 -1.0
21 CXOU J235704.0-005859 23 57 4.03 -0 58 58.8 8 -0.2
22 CXOU J235707.2-010420 23 57 7.18 -1 4 19.6 7 0.4
We estimate a position uncertainty of 1.0" for the Chandra sources.
Astrometry was performed using five stars from the USNO-A2 catalog.
The column labeled HR in the table above refers to the hardness
ratio ( Cts_2-8keV - Cts_0.5-2keV )/ Cts_0.5-8 keV. This quantity is
typically in the range -0.5 to -0.1 for GRBs at high Galactic latitude
and attenuated by the Galactic absorption only.
An image of the Chandra data, with the detected sources overlaid, can
be found at http://space.mit.edu/HETE/Bursts/GRB040912.
We gratefully acknowledge the timely assistance of the observatory staff
at the Chandra Science Center in arranging for the acquisition and
preliminary processing of these data.
This message may be cited.