TITLE: GCN CIRCULAR NUMBER: 17405 SUBJECT: GRB 150202B: Swift XRT/UVOT observations DATE: 15/02/04 19:37:11 GMT FROM: Boris Sbarufatti at INAF-OAB/IASFPA B. Sbarufatti (INAF-OAB/PSU), F. E. Marshall (NASA/GSFC), A. Maselli (INAF-IASFPA), A. Melandri (INAF-OAB), V. Mangano (PSU), M.C. Stroh (PSU), D.N. Burrows (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), C. Pagani (U. Leicester) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the Fermi/LAT-detected burst GRB 150202B (Axelsson et al. GCN Circ. 17385) in a series of observations tiled on the sky. The total exposure time is 4.2 ks, distributed over 2 tiles; the maximum exposure at a single sky location was 4.7 ks. The data were collected between T0+95.4 ks and T0+107.3 ks, and are entirely in Photon Counting (PC) mode. Four uncatalogued X-ray sources have been detected, however none of them is above the RASS limit or shows definitive signs of fading. Therefore, at the present time we cannot identify which, if any, is the afterglow. Details of these sources are given below: Source 1: RA (J2000.0): 86.9565 = 05:47:49.57 Dec (J2000.0): +58.8301 = +58:49:48.2 Error: 4.1 arcsec (radius, 90% conf.) Count-rate: 0.0183 +/- 0.0030 ct s^-1 Flux: (6.1 +/- 1.0)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 2: RA (J2000.0): 86.5922 = 05:46:22.14 Dec (J2000.0): +58.9223 = +58:55:20.5 Error: 5.7 arcsec (radius, 90% conf.) Count-rate: (5.9 +/- 1.9) -3 ct s^-1 Flux: (3.2 +/- 1.0)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 3: RA (J2000.0): 86.7927 = 05:47:10.25 Dec (J2000.0): +58.7852 = +58:47:06.8 Error: 6.4 arcsec (radius, 90% conf.) Count-rate: (4.0 +/- 1.7) -3 ct s^-1 Flux: (1.60 +/- 0.67)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 4: RA (J2000.0): 86.8219 = 05:47:17.25 Dec (J2000.0): +58.9746 = +58:58:28.7 Error: 5.5 arcsec (radius, 90% conf.) Count-rate: (3.03 +/- 0.99) -3 ct s^-1 Flux: (6.5 +/- 2.1)e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV) Sources 3 and 4 are positionally coincident with stars from the USNO B1 catalogue. The results of the XRT-team automatic analysis of the tiled XRT observations, including a position-specific upper limit calculator, are available at http://www.swift.ac.uk/xrt_products/TILED_GRB00039. The UVOT observation covers sources 1 and 3 in the UVW1 filter. There is nothing at the position of source 1; source 3 is bright as expected from the catalogued source. This circular is an official product of the Swift-XRT team.