TITLE: GCN CIRCULAR NUMBER: 17634 SUBJECT: GRB 150323B: Swift-XRT observations DATE: 15/03/24 11:07:30 GMT FROM: Phil Evans at U of Leicester P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), M. de Pasquale (INAF-IASFPA), D.N. Burrows (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/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 Swift/BAT-detected burst GRB 150323B (Cummings et al. GCN Circ. 17619), collecting 4.6 ks of Photon Counting (PC) mode data between T0+40.4 ks and T0+63.2 ks. Two uncatalogued X-ray sources have been detected inside or close to the Swift/BAT error region, 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): 260.4534 = 17:21:48.83 Dec (J2000.0): +38.3179 = +38:19:04.6 Error: 4.3 arcsec (radius, 90% conf.) Count-rate: 0.0103 +/- 0.0018 ct s^-1 Flux: (4.62 +/- 0.80)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 2: RA (J2000.0): 260.4598 = 17:21:50.35 Dec (J2000.0): +38.2829 = +38:16:58.5 Error: 6.6 arcsec (radius, 90% conf.) Count-rate: (2.3 +/- 1.0)e-3 ct s^-1 Flux: (9.2 +/- 4.1)e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV) The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at http://www.swift.ac.uk/ToO_GRBs/00020485. This circular is an official product of the Swift-XRT team.