astro-ph更新

考，连blogger都不能访问了。看来以后只有从邮件发送了，但看怎么办呢？

今天更新了一篇grb的文章。

 

astro-ph/0611031 [abs, ps, pdf, other] :

Title: Refined Astrometry and Positions for 179 Swift X-ray Afterglows
Authors: N.R. Butler
Comments: 8 pages, 5 figures, 3 tables, Submitted to AJ Sept. 11, 2006

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 November 1, 2006. 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 (DSS) red2 catalog or the Sloan Digital Sky Survey (SDSS) DR-5 catalog. Half of the 90% confidence error region radii are < 2.2 arcseconds. 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 ksec) 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 afterglows positions require a sizable shift in the Swift satellite aspect. We discuss the optical/X-ray properties of the field sources and discuss implications of the frame offsets for studies of optically dark GRBs.