TITLE: GCN CIRCULAR NUMBER: 10300 SUBJECT: GRB 091230: Swift-XRT observation DATE: 09/12/31 01:45:38 GMT FROM: Andy Beardmore at U Leicester A. P. Beardmore (U. Leicester) and H. A. Krimm (CRESST/GSFC/USRA) report on behalf of the Swift-XRT team: At 2009-12-30 15:25UT Swift performed a TOO observation of the INTEGRAL discovered long GRB 091230 (Gotz et al., GCN Circ. 10298). In 3.7 ks of XRT Photon Counting (PC) mode data, taken from 32.3 ks to 39.4 ks after the INTEGRAL trigger, we find an X-ray source within the INTEGRAL error circle, with a 0.3-10 keV count rate of 0.01 count/s. Using 1096 s of PC mode data and 1 UVOT image, the enhanced XRT position for this source (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue, as described by Goad et al., 2007, A&A, 476, 1401 and Evans et al., 2009, MNRAS, 397, 1177) is: RA, Dec = 132.91150, -53.89780, which is equivalent to: RA (J2000): 08 51 38.77 Dec(J2000): -53 53 52.0 with an uncertainty of 2.7 arcsec (radius, 90% confidence). This position lies 3.8 arcsec from the location of the Grond optical/NIR afterglow candidate (Filgas et al., GCN Circ. 10299). At this stage, we cannot tell whether the X-ray source is fading, but its coincidence with the Grond candidate suggests it is likely the X-ray counterpart to GRB 091230. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00020124. This circular is an official product of the Swift-XRT team.