TITLE: GCN CIRCULAR NUMBER: 13909 SUBJECT: GRB 121025A: Swift-XRT observation DATE: 12/10/27 10:34:49 GMT FROM: Kim Page at U.of Leicester K.L. Page, R.L.C. Starling and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team: Swift performed a Target of Opportunity observation of the MAXI-detected GRB 121025A (Asada et al., GCN Circ. 13895), starting 26.1 ks after the trigger. A series of four tiled pointings was performed, in order to cover the MAXI error circle. Within these fields, one > 3 sigma uncatalogued source was detected, at RA, Dec = 248.38182, 27.67189, which is equivalent to: RA(J2000) = 16h 33m 31.64s Dec(J2000) = 27d 40' 18.8" with an uncertainty of 3.8 arcsec (radius, 90% containment). This source has a mean count rate of 0.022 +/- 0.004 count s^-1. A spectrum formed from the 1.8 ks of data can be fitted with an absorbed power-law with a photon spectral index of 2.36 (+0.57,-0.56). The best-fitting absorption column is consistent with the Galactic value of 3.8 x 10^20 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.7 x 10^-11 (4.5 x 10^-11) erg cm^-2 count^-1. It is not possible to determine whether this source is fading at this time and, therefore, whether it is the X-ray afterglow. This circular is an official product of the Swift-XRT team.