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GCN Circular 3253

GRB 050412: early Swift XRT analysis results
2005-04-12T19:10:35Z (19 years ago)
David Burrows at PSU/Swift <>
V. Mangano (IASF/Palermo), M. Capalbi (ASDC), C. Pagani (INAF-OAB), M. Goad 
(U. Leicester), J. Kennea and D. Burrows (PSU) report on behalf of the 
Swift XRT team:

We have analyzed the Swift XRT data from the first orbit observation of GRB 
050412 (Tamburelli et al., GCN3241). The new refined coordinates are:

RA(J2000) = 12h 04m 25.5s
Dec(J2000) = -01:12:00.2

This position is 65.6 arcseconds from the refined BAT position given in GCN 
3251 (Tueller et al. 2005) and 3.6 arcsec from the preliminary XRT position 
(GCN3241). We estimate an uncertainty of 5 arcseconds radius (90% containment).

The [0.2-10] keV light curve in Windowed Timing (WT) and Photon Counting 
(PC) mode starts ~100 seconds from the BAT trigger (T0). We clearly detect 
a rapidly fading source.

A preliminary spectral fit to the WT data gives a spectral power law photon 
index of 1.35 +/- 0.2 in the [0.5-10] keV band, assuming Galactic 
absorption (2.21E20cm^-2). The average (~10000 seconds from trigger) 
estimated unabsorbed 0.5-10 keV flux is then about 3.9E-12 erg cm^-2 s^-1.
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