GCN Circular 3443
Subject
GRB 050520: Swift XRT refined analysis
Event
Date
2005-05-20T20:40:49Z (21 years ago)
From
Jamie A. Kennea at PSU/Swift-XRT <kennea@astro.psu.edu>
M. Perri, M. Capalbi, P. Giommi (ASDC), J. A. Kennea, D. N. Burrows (PSU),
J. Norris, N. Gehrels (GSFC) report on behalf of the Swift XRT team:
We have analyzed the Swift XRT data from the GRB 050520 discovered by INTEGRAL
(Gotz et al., GCN 3430). The source identified by Kennea et al. 2005 (GCN 3434)
is clearly fading and is therefore the likely X-ray afterglow of this burst.
The new refined coordinates of the X-ray afterglow are:
RA(J2000) = 12:50:06.2
Dec(J2000) = 30:27:02
This position is 53 arcseconds from the INTEGRAL position given in GCN 3430
(Gotz al. 2005) and 4 arcsec from the preliminary XRT position reported in GCN
3434 (Kennea et al. 2005). We estimate an uncertainty of 5 arcseconds radius
(90% containment). The first and second sources reported in GCN 3438 (Cenko et
al. 2005) are 5.4 and 7 arcseconds from the center of our refined error circle,
respectively.
The total exposure time in Photon Counting (PC) mode is 16860 seconds starting
from 02:13:39 UT to 14:52:09 UT on 20 May 2005. The 0.3-10 keV light curve can
be fitted by a single power law with decay index alpha = -1.4 +/- 0.6.
The average source count rate (0.5-10 keV) is (2.8+/-0.5)e-3 cts/s. Assuming a
Crab-like spectrum and Galactic absorption (1.2e20 cm^-2) the average estimated
unabsorbed 0.5-10 keV flux is 1.0e-13 erg cm^-2 s^-1.