[vsnet-grb-info 2034] GRB 050822: refined XRT analysis

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3873
SUBJECT: GRB 050822: refined XRT analysis
DATE:    05/08/25 09:48:17 GMT
FROM:    Kim Page at U.of Leicester,Swift SDC  <kpa at star.le.ac.uk>

O. Godet, K.L. Page, J.P. Osborne (U. Leicester), D. N. Burrows (PSU),
N. Gehrels (NASA/GSFC), K. Hurley (Berkeley), M. Chester (PSU) report on
behalf of the Swift XRT team:

We have analysed the Swift XRT data taken up to 200 ksec (2.3 days) from
the burst GRB 050822. The refined coordinates are:

RA(J2000) = 03h 24m 26.70s
Dec(J2000) = -46d 02' 01.7"

with an uncertainty of 6 arcseconds radius (90% containment).
This position is consistent with that reported by Blustin et al. (GCN
3849).

Initial data show a rapid decay until ~1000 sec, followed by a shallow
decay (power law decline index ~0.4) until ~20 ksec. After this the flux
declines more steeply, with an index ~1.2.

The X-ray spectrum before and after the ~20 ksec break is well fit
by a power-law with Gamma = 2.17+/-0.28 (90% confidence) and an
absorbing column of ~1.4e21 cm^-2 in excess of Galactic in the observer
frame.

At 200 ksec after the burst the XRT count rate was 0.007 c/s,
corresponding to an unabsorbed 0.3-10 keV flux of 3x10^-13 erg/cm2/s.