TITLE: GCN CIRCULAR NUMBER: 6255 SUBJECT: GRB 070406: Swift XRT Team analysis - Possible X-ray counterpart DATE: 07/04/07 19:36:58 GMT FROM: Eleonora Troja at INAF-IASFPA E. Troja (U. Leicester/INAF-IASFPa), Kim Page (U. Leicester) and S. McBreen (MPE) report on behalf of the Swift XRT team: We analysed the first 13 orbits of Swift XRT data for GRB 070406 (Cummings et al., GCN Circ. 6247), taken between 20.6 hr and 35.5 hr after the BAT trigger. Swift did not autonomously slew because the burst was below the trigger threshold. In the Photon Counting mode image (13 ks of exposure) no source is detected at the position of the optical candidate, proposed by Xin et al. (GCN Circ. 6253), with a 3-sigma upper limit of 1.5E-03 cts/s. A faint uncatalogued X-ray source is detected within the BAT error circle. The source is located at: RA(J2000)= 13h 15m 51.35s Dec(J2000)=+16d 30' 46.9" with an error radius of 5" (90% containment). This lies 68 arcsec from the BAT position given in GCN Circ. 6247. We note that the projected offset of the source from the bright galaxy quoted in Ofek et al. (GCN Circ. 6249) is 45". At a redshift of z=0.11 it corresponds to 89 kpc. With the data so far available we can not tell if the source is fading. Further Swift observations are ongoing. This circular is an official product of the Swift XRT Team. [GCN OPS NOTE(09apr07): Per author's request, the word 'counterpart' was added to the Subject line, and the Instituitional trailer signifying it is virus-free was removed.]