TITLE: GCN CIRCULAR NUMBER: 6187 SUBJECT: GRB070309: Swift/XRT possible afterglow detection DATE: 07/03/10 00:14:35 GMT FROM: Pat Romano at OAB-Swift S.D. Vergani (Dunsink observatory-DIAS, DCU), P. Romano (INAF-OAB, Univ. Bicocca), C. Guidorzi (INAF-OAB, Univ. Bicocca) report on behalf of the Swift-XRT team: We have analyzed the Swift XRT data from the first 11ks observations of INTEGRAL GRB 070309 (Paizis, et al. 2007, GCN Circ. 6182). Inside the INTEGRAL error circle we find one source at the position RA(J2000) = 17h 34m 39.1s Dec(J2000) = -37d 55' 48.2" with an estimated error radius of ~5 arcsec (90% confidence). This is 81 arcseconds from the INTEGRAL position. The source has a count rate of (2.0+-0.6)E-3 counts/s and, assuming a crab spectrum, a flux of 5E-14 erg/cm2/s. We collected a total of 15 counts. More data are being collected that will be used to determine whether the source is fading and to perform a spectral analysis. This Circular is an official product of the Swift XRT Team.