GCN Circular 836
Subject
GRB 000926 Chandra Observation
Event
Date
2000-10-06T21:27:15Z (26 years ago)
From
Gordon Garmire at Penn State U <garmire@astro.psu.edu>
TITLE: GCN GRB OBSERVATION REPORT
NUMBER: GCN 836
SUBJECT: GRB000926: X-ray afterglow by Chandra X-ray Observatory
DATE: 00/10/06 22:29:00 GMT
FROM: G. Garmire at Penn State University <garmire@astro.psu.edu>
G. Garmire and A. Garmire (Penn State U), L. Piro (IAS/CNR Roma) and M. R. Garcia (CfA)
A Chandra X-ray Observatory TOO observation of the afterglow from GRB000926
began September 29.67375 and ended on 29.85125, but with a total good time
of observation of 9979s. The source position determined by CXO is:
RA(2000)=17h 04m 09.6s Decl. (2000)= +51 47' 8.6"
with an uncertainty of ~2", consistant with the optical position
by Gorosabel et al. GCN 803, Dall et al. GCN 804, Halpern et al. GCN 806.
The average flux of the source is (3.08+/-.017) 10^-2 cts/s, corresponding to a
flux F(1.6-10 keV)=(9.4+/-0.95)10^-14 erg/cm2/s.
The spectrum is found to fit a powerlaw with powerlaw index =(1.76+/-0.2)
consistant with the slope of Piro et al. GCN 832, and the absorption
by our Galaxy (NH=2.7 10^20 cm-2).
This very large decrease in flux in such a short time is unprecedented,
decreasing by a factor of ~3 in only ~12 hours from the BeppoSAX measurement!
To obtain a better measure of the slope with time for a law of the
form F=c(T-T0)^d_X with T0=26.99 will require a more refined analysis,
since taking average values leads to a slope of -5!