GCN Circular 9091
K.L. Page (U. Leicester) & H. Ziaeepour (UCL-MSSL) report on behalf of the Swift-XRT team: We have analysed the first 3 orbits of XRT data obtained for GRB 090404 (Ziaeepour et al. 2009, GCN Circ. 9086), comprising 129 s in Windowed Timing mode and 5.4 ks in Photon Counting (PC) mode. The UVOT-enhanced position was given by Beardmore et al. (GCN Circ. 9088). The X-ray afterglow was initially very bright, starting at a count rate of ~1200 count s^-1. The light-curve can be approximately modelled with a doubley broken power-law: alpha1 = 3.2 +/- 0.3 until around 120 s after the burst, at which point the decay steepened to a slope of alpha2 = 9.3 +/- 0.3. After 265 s, the decay is much more gradual, with alpha3 = 0.17 +/- 0.06. The data show significant softening until at least 150 s after the trigger. A spectrum extracted from the first orbit of PC data can be fitted with a power-law of Gamma = 3.0 +/- 0.5 and a total absorbing column of 5.1x10^21 cm^-2, which is in excess of the Galactic value of 2.0x10^20 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.1x10^-11 (1.4x10^-10) erg cm^-2 count^-1. If the light-curve continues to decay with alpha ~ 0.17, the predicted count rate at 24 hours is 0.14 count s^-1, corresponding to an observed (unabsorbed) flux of 4.3x10^-12 (2.0x10^-11) erg cm^-2 s^-1. However, we note that it is unlikely that the light-curve decay will still be this flat at 24 hours. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00348428. This circular is an official product of the Swift-XRT team.