TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  2328
SUBJECT: XRF030723(=H2777): Chandra Observations
DATE:    03/07/26 17:38:58 GMT
FROM:    George Ricker at MIT  <grr@space.mit.edu>

XRF030723(=H2777): Observations with the Chandra X-ray Observatory

N. Butler, P. Ford, G. Ricker, R. Vanderspek, J. Villasenor (MIT); D.
Lamb (U. Chicago); G. Garmire (PSU); L. Piro (CNR); and J.G. Jernigan
(UCB), on behalf of a Chandra GRB ToO Team,

write:

On 25 July 2003, the Chandra Observatory targeted the field of 
XRF030723, an X-ray flash localized by the HETE satellite (=H2777; 
Prigozhin et al, GCN 2313). The 25 ksec observation spanned the 
interval 09:52-17:05 UT on 25 July, 51.4 - 59.0 hours after the 
burst. The SXC error circle from Prigozhin et al. was completely 
contained within the field-of-view of the Chandra ACIS-I array.

Within the SXC error circle, we detect 3 sources in the 0.5-8 keV band:

#      Chandra Name           RA           DEC         Cts
1 CXOU J214924.4-274248   21 49 24.421  -27 42 48.00   78
3 CXOU J214926.9-274146   21 49 26.891  -27 41 45.92   19
4 CXOU J214928.7-274211   21 49 28.724  -27 42 11.47   16

The brightest object within the SXC error circle, Chandra Source #1, 
lies 62" from the center of the SXC error circle, and is within 0.7" 
of the optical transient reported by Fox et al. (GCN 2323). We 
estimate a position uncertainty of 1.4" for the Chandra sources. 
Astrometry was performed using six stars from the USNO-A2 catalog.

The Chandra results provide further evidence that the optical 
transient reported by Fox et al. (GCN 2323; see also Wood-Vasey et 
al., GCN 2325) and confirmed by Dullighan et al. (GCN 2326) is indeed 
the counterpart and afterglow of XRF030723.

We gratefully acknowledge the timely assistance of Roger Brissenden 
and the observatory staff at the Chandra Science Center in arranging 
for the acquisition and preliminary processing of these data.

This message may be cited.