GCN Circular 4320
V. Mangano, G. Cusumano, V. La Parola (INAF-IASF), D. N. Burrows (PSU), L. Angelini (GSFC-JHU), and N. White (GSFC) report on behalf of the Swift team: We have analyzed the Swift XRT data from the first observation of GRB 051210 (Mangano et al. 2005, GCN 4315) consisting of three orbits (about 5.7 ks exposure). The refined coordinates of the X-ray afterglow are: RA(J2000) = +22h 00m 41.3s Dec(J2000) = -57d 36' 48.2" with an estimated uncertainty of 4.2 arcseconds radius (90% containment). The XRT boresight correction has been applied through the new TELDEF file provided by the Swift Science Data Center (Angelini et al. 2005, GCN 4313). This position is 54.4 arcsec from the revised BAT position given in GCN 4318 (Sato et al. 2005) and 3 arcsec from the XRT position determined on board (Mangano et al. 2005, GCN 4315). The 0.2-10 keV light curve, that starts in Windowed Timing (WT) mode 87.3 seconds after the BAT trigger, shows a fading behaviour with a decaying slope of 2.3+/-0.1 over the first two orbits and is not detectable anymore during the third (the expected count rate at the end of the third orbit would be 7.0e-4 c/s). A preliminary spectral fit to WT and PC data of the first two orbits with an absorbed power law gives a photon index of 1.5+/-0.1 and an absorption column of (7.5 +/- 3) x 1e20 cm^-2. The Galactic absorption in the GRB direction is 2.2e20 cm^-2. Assuming the current steep decay we predict a flux lower than 1.e-16 erg cm^-2 s^-1 at one day from the burst.