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GCN Circular 2975

GRB050124: Updated Swift XRT Position and Fluxes
2005-01-24T23:18:00Z (19 years ago)
David Burrows at PSU/Swift <>
J. P. Osborne, K. Page, M. Goad (UL), A. Beardmore, A. F. Abbey, A. A. 
Wells (U. Leicester), S. Campana, A. Moretti, C. Pagani,  P. Romano, G. 
Tagliaferri, G. Chincarini (OAB), L. Angelini, F. Marshall, N. Gehrels 
(NASA/GSFC), J. E. Hill, J. Kennea, D. N. Burrows, J. A. Nousek, P. Roming, 
P. Meszaros (PSU), G. Cusumano, V. Mangano (IFSFC), P. Schady (MSSL), and 
S. Piranomonte (ASDC) report on behalf of the Swift XRT team:

We have obtained a refined XRT position, using the ground-based pipeline 
processing software, including stellar aberration correction.  The refined 
position for the X-ray afterglow is: RA(J2000) = 12:51:30.4, Dec(J2000) = 
+13:02:39.0.  We estimate a remaining uncertainty of about 8 arcseconds, 
including a systematic error of about 5 arcseconds due to residual 
alignment offsets that have not been fully calibrated yet.

We now have data from 3 orbits.  Data were collected between 14:35:15 and 
15:17:12 UT, between 16:11:35 and 16:53:41 UT, and between 17:48:02 and 
18:30:03.  The point source is clearly fading, with average observed count 
rates 0.20 cps, 0.14 cps, and 0.09 cps in the three observations.

A preliminary spectral fit to data from the first orbit gives a spectral 
power law photon index of  1.3 +/- 0.1, assuming Galactic absorption (2E20 
cm^-2).  The average estimated unabsorbed 1-5 keV flux is then about 6E-12 
erg cm^-2 s^-1 at about 3.5 hours post-burst.
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