GCN Circular 9550
A.P. Beardmore, K.L. Page (U. Leicester) and P.A. Curran (UCL-MSSL) report on behalf of the Swift-XRT team: We have analysed five orbits of Swift-XRT photon counting (PC) mode data from GRB 090621B (Curran et al., GCN Circ. 9545), spanning the interval T+80 s to T+19.5 ks after the trigger. In 10.0 ks we find a refined XRT position of RA, Dec = 313.47049, 69.02845, which is equivalent to RA (J2000) = 20:53:52.92 Dec(J2000) = +69:01:42.4 with an uncertainty of 4.0 arcsec (90% containment). This position is 1.2 arcsec from the XRT position quoted in GCN Circ. 9545. The X-ray light-curve shows a faint, fading source with a decay index of 0.61 +/- 0.19. If the source continues to decay at the same rate we predict an XRT count rate of 8.6e-4 count s^-1 at T+24 hours. The PC mode spectrum from T+80 s to T+17.1 ks can be fit by an absorbed powerlaw with a photon index of 1.47+/-0.66, assuming a Galactic column density of 1.9e21cm^-2 in the direction of the burst. The observed (unabsorbed) 0.3-10keV flux for this model is 3.8e-13 (4.5e-13) erg cm^-2 s^-1. This circular is an official product of the Swift-XRT team.