GCN Circular 7490
Subject
GRB 080319D: Swift XRT refined analysis
Date
2008-03-20T20:01:09Z (16 years ago)
From
Dirk Grupe at PSU/Swift-XRT <grupe@astro.psu.edu>
Dirk Grupe and Peter Brown (PSU) report on behalf of the Swift-XRT team:
The Swift-XRT started observing GRB 080319D (trigger=306793, Brown et
al. GCN
7453) at 17:07:37 UT, 148 seconds after the BAT trigger.
The astrometrically corrected X-ray position (using the XRT-UVOT
alignment and
matching UVOT field sources to the USNO-B1 catalogue) is: RA, Dec =
99.47254,
+23.94275 which is equivalent to:
RA (J2000): 06 37 53.41
Dec (J2000): +23 56 33.9
with an uncertainty of 1.7 arcsec (radius, 90% confidence).
The 0.3-10 keV X-ray light curve starts with three flares up to 20
counts/s. The
afterglow decays very fast and started to flatten at about 1000 s after the
burst. The light curves shows another break at about 5 ks after the
burst and is
currently decaying with a decay slope of 1.3.
The spectrum of the PC data can be well fit by an absorbed single
powerlaw with photon index 2.12 � 0.27 and column density of
(3.8 � 1.4)e21 cm-2. This is in excess of
the Galactic column density of 2.17e21 cm-2 in this direction.
Using this spectrum we estimated a count rate to flux conversion of
1 count/s converts to 6.28e-11 ergs/cm2/s.
If the underlying powerlaw decay continues as is, we predict an XRT
count rate
of 1.6e-3 counts/s at T+24 hours and 6.5e-4 counts/s at T+48 hours
after the burst, or 1.0e-13 ergs/s/cm2 and 4.1e-14 ergs/s/cm2,
respectively.
This circular is an official product of the Swift-XRT team.