GCN Circular 7494
Dirk Grupe reports on behalf of the Swift-XRT team: The XRT began observing the field of GRB 080320 (trigger=306858; Grupe et al., GCN Circ 7473) at 04:40:29.4 UT, 171.0 seconds after the BAT trigger. The astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue) is: RA, Dec = 177.7353, +57.1574 which is equivalent to: RA (J2000): 11 50 56.46 Dec (J2000): +57 09 26.8 with an uncertainty of 1.4 arcsec (radius, 90% confidence). The 0.3-10 keV X-ray light curve starts with three flares up to 12 counts/s. The afterglow decays very fast and started to flatten at the end of the first orbit about 1000 s after the burst. The light curve is currently decaying with a shallow decay slope of 0.63 +/- 0.05. The spectrum of the Photon Counting data of the first three orbits can be well fitted by an absorbed single powerlaw with a photon index Gamma = 1.96 +/- 0.20 and column density of (6.9 +/- 4.0)e20 cm-2 This is slightly in excess of the Galactic column density of 1.35e20 cm-2 in this direction. Using this spectrum we estimated a count rate to flux conversion of 1 count/s converts to 4.22e-11 ergs/cm2/s. If the underlying powerlaw decay continues as is, we predict an XRT count rate of 0.026 counts/s at T+24 hours or 1.1e-12 ergs/s/cm2.