TITLE: GCN CIRCULAR NUMBER: 22417 SUBJECT: Swift J1658.2-4242 (trigger 810300): Swift-XRT position DATE: 18/02/16 07:47:24 GMT FROM: Paolo D'Avanzo at INAF-OAB P. D’Avanzo, A. Melandri (INAF-OAB) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team: Swift-XRT has performed observations of the probable new Galactic source Swift J1658.2-4242 (trigger=810300; Barthelmy et al. GCN Circ. 22416), collecting 137 s of Photon Counting (PC) mode data between T0+5.9 ks and T0+6.1 ks. Using promptly downlinked data we find an uncatalogued X-ray source located at RA,Dec = 254.5524, -42.6988 which is equivalent to: RA (J2000.0) = 16 58 12.58 DEC (J2000.0) = -42 41 55.7 with an uncertainty of 3.83 arcsec (radius, 90% containment). This location is 41.6 arcsec from the BAT position, inside the BAT error circle. This circular is an official product of the Swift-XRT team