2006/11/30 by N. R. Butler, N. Butler · 2 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Gamma-ray bursts and supernovae #astro-ph
paper · pdf · doi:10.1086/510836
published as Astron.J.133:1027-1033,2007 · 8 pages, 5 figures, 3 tables, Accepted to AJ
arxiv created 2006/12/22 · openalex publication_date 2007/02/06 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/30
We present a refined catalog for the positions of 179 gamma-ray burst (GRB) X-ray afterglows observed by the X-Ray Telescope (XRT) on Swift prior to 2006 November 1. The positions are determined by detecting X-ray field sources in the deep X-ray images and comparing the centroids to those of optical sources in the Digitized Sky Survey red2 catalog or the Sloan Digital Sky Survey Data Release 5 catalog. Half of the 90% confidence error region radii are <2.2''. The error regions areas are typically ∼4 times smaller than the best XRT team error regions, although the positions require deep X-ray integration (>20 ks) and cannot be generated nearly as rapidly after the GRB. The positions derived for >90% of 77 bursts with optical afterglows are consistent with the optical transient positions, without the need for systematic error. About 20% of the afterglow positions require a sizable shift in the Swift satellite aspect. We discuss the optical/X-ray properties of the field sources and discuss the implications of the frame offsets for studies of optically dark GRBs.