GCN Circular 6323
Subject
GRB 070419B: Swift XRT refined analysis
Date
2007-04-19T22:41:38Z (18 years ago)
From
Giulia Stratta at ASDC <stratta@asdc.asi.it>
We have analyzed the first 3 orbits of Swift-XRT data on GRB 070419B
(Parsons et al. GCN 6305), with a total exposure of 276 s in Windowed
Timing (WT) mode and of 4.5 ks in Photon Counting (PC) mode.
This provides a refined XRT position at RA,DEC=315.70654,-31.26381
which is:
RA(J2000)=21 02 49.57
Dec(J2000)=-31 15 49.7
with an estimated error radius of 3.5 arcseconds (90% confidence).
This position is 32 arcseconds from the BAT position
(Parsons et al. GCN 6305), 1.2 arcseconds from the initial XRT
position (Parsons et al. GCN 6305) and 3.0 arcseconds from the
optical candidate (Tristram et al. GCN 6314).
The 0.3-10 keV X-ray light curve presents a flaring behavior
starting from 88 s up to about 350 s after the burst, with three
flares. The second and third orbits data taken in PC mode show marginal
evidence of a flat decay between 3.8 ks and 6.0 ks after the trigger,
followed by a fading decay behavior that can be fit with a power law
model with decay index 1.3+/-0.1
The X-ray spectrum from the XRT/WT data from 88 s to about 350 s can
be fit by an absorbed power law with a photon index of 1.88+/-0.03
and a total column density of NH=(0.22+/-0.01)e22 cm**-2. We note that
the Galactic column density in the direction of the source is
6.7e20 cm**-2 (Dickey & Lockmann 1990).
Assuming the X-ray emission continues to decline at the same rate,
we predict a 0.3-10.0 keV XRT count rate of 7.5e-2 count/s at T+24h
and 3.1e-2 at T+48h.
This circular is an official product of the Swift Team.