GCN Circular 3275
Subject
GRB050416: Refined Swift-XRT analysis
Date
2005-04-16T18:37:28Z (19 years ago)
From
Jamie A. Kennea at PSU/Swift-XRT <kennea@astro.psu.edu>
G. Cusumano, V. La Parola, T. Mineo, V. Mangano (IASF/Palermo), G.
Chincarini, S. Campana, G. Tagliaferri, P. Romano, P. Giommi, M. Perri
(INAF-OAB), M. Capalbi (ASDC), D. N. Burrows, J. A. Kennea (PSU), N.
Gehrels (NASA/GSFC)
We have analyzed the Swift-XRT data from the first orbit observation of
GRB050416 (Sakamoto et al. 2005, GCN3264). The new refined coordinates
are:
RA(J2000) = 12:33:54.8
Dec(J2000) = +21:03:25.1
This position is 17.7 arcseconds from the BAT position given in GCN 3273
(Sakamoto et al. 2005) and 1.3 arcsec from the preliminary XRT position
(GCN3268, Kennea et al. 2005). We estimate an uncertainty of 5 arcseconds
radius (90% containment).
The [0.2-10] keV light curve in Photon Counting (PC) mode starts ~90
seconds from the BAT trigger (T0). We clearly detect a rapidly fading
source. The light curve can be fitted with a single power law with alpha=
-0.6 +/- 0.3.
A preliminary spectral fit to the PC data gives a spectral power law
photon index of 2.02+/-0.21 in the [0.2-10] keV band, with a column
density of (0.25+/-0.05)E22 cm^-2 (the Galactic line-of-sight absorption
is 2.06E20 cm^-2). The average estimated unabsorbed 0.2-10 keV flux is
1.7E-11 erg cm^-2 s^-1.