[AAVSO-HEN] GRB 090823: Swift XRT confirmation of the X-ray afterglow

[grb at aavso.org]

The following is a GCN Circular circulated via the AAVSO network.
For an archive and more information on circulars visit:
http://lheawww.gsfc.nasa.gov/docs/gamcosray/legr/bacodine/gcn3_archive.html

TITLE:   GCN CIRCULAR
NUMBER:  9902
SUBJECT: GRB 090823: Swift XRT confirmation of the X-ray afterglow 
DATE:    09/09/08 17:33:53 GMT
FROM:    Dirk Grupe at PSU/Swift-XRT  <grupe at astro.psu.edu>

D. Grupe (PSU)  reports on behalf  of the Swift XRT team:

Swift has observed the field of IPN burst GRB090823 (Cummings et
al. GCN Circ. 9835) twice after the initial 4.7 ks observation
on 2009-08-24 (Grupe et al., GCN Circ. 9840) for 9.5 ks on
2009-08-27 and 7.5 ks on 2009-09-05. During the 2009-08-27
observation the X-ray source was clearly detected again at a level
of (2.3+/-0.6)e-3 counts s-1 (about 1.1e-13 ergs s-1 cm-2), roughly
half of the flux during the first observation. During the
2009-09-05 observation however, the X-ray source is definitely
gone and we can only derive a 3-sigma upper limit at a level of
1.9e-3 counts s-1 (9.4e-14 ergs s-1 cm-2). We can confirm that the
source listed in GCN circ. 9840 is the X-ray afterglow of
GRB 090823.