TITLE: GCN CIRCULAR NUMBER: 10802 SUBJECT: GRB 100526B: Swift XRT/UVOT observations DATE: 10/05/26 20:30:55 GMT FROM: Jamie A. Kennea at PSU/Swift-XRT J. A. Kennea, L. Vetere and M. Siegel (PSU) report on behalf of the Swift team: The XRT began observing the field of GRB 100526B at 19:55:21.1 UT, 3282.6 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 0.73552, -37.91195 which is equivalent to: RA(J2000) = 00h 02m 56.52s Dec(J2000) = -37d 54' 43.0" with an uncertainty of 5.6 arcseconds (radius, 90% containment). This location is 107 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper. We cannot determine whether the source is fading at the present time. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 1.12e+20 cm^-2 (Kalberla et al. 2005). UVOT took a finding chart exposure of 150 seconds with the White filter starting 3288 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers none of the XRT error circle. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.01.