TITLE: GCN CIRCULAR NUMBER: 6286 SUBJECT: GRB 070411: Swift-XRT refined analysis DATE: 07/04/12 10:58:22 GMT FROM: Alberto Moretti at Obs Brera Merate A. Moretti (INAF-OAB), P. Romano (Univ. Bicocca & INAF-OAB), C. Guidorzi (Univ. Bicocca & INAF-OAB) report on behalf of the Swift-XRT team: We have analysed the first 4 orbits of Swift-XRT data obtained for GRB 070411 (trigger=275087, GCN 6267). At the moment the 1st orbit dataset is not complete. The currently available data consist of 4.2 ks in Photon Counting (PC) starting 500 seconds after the BAT trigger. Using PC data we obtain a refined position of: RA(J2000) = 07h 09m 19.96s Dec(J2000)= +01d 03' 51.8" with an estimated uncertainty radius of 3.7 arcsec (90% containment). This location is 1.2 arcseconds from the UVOT position (GCN 6267). The afterglow shows a decay which can be fitted well by a single power law (alpha=0.87+/-0.08) up to the end of the fourth orbit (t=17.0 ks). At this point the observed count rate was 6.8E-2 counts per second, corresponding to an unabsorbed flux of 5.2E-12 erg/cm2/sec. At 24 hours from the burst the expected afterglow unabsorbed flux is 1.1E-12 erg/cm2/sec (1.4E-2 counts per second). The spectrum formed from the PC data can be modelled with a an absobed power-law of photon index Gamma = 2.1 +/- 0.2 and and an absorption column density consistent with the Galactic value (2.9+/-0.9 E21 cm^-2; Dickey & Lockman, 1990). All errors are quoted at 90% confidence level. This circular is an official product of the Swift-XRT team.