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Paper: Cross-matching Within the Chandra Source Catalog
Volume: 521, Astronomical Data Analysis Software and Systems XXVI
Page: 424
Authors: Rots, A.; Burke, D.; Civano, F.; Hain, R.; Nguyen, D.
Abstract: Cross-matching among overlapping source detections in the development of the Chandra Source Catalog (CSC) presents considerable challenges, since the Point Spread Function (PSF) of the Chandra X-ray Observatory varies significantly over the field of view. For the production of the second release of the CSC we have developed a cross-match tool that is based on the Bayesian algorithms by Budavari, Heinis, and Szalay, making use of the error ellipses for the derived positions of the detections. However, calculating match probabilities only on the basis of error ellipses breaks down when the PSFs are significantly different. This is an issue that is not commonly addressed in cross-match tools. We have applied a satisfactory modification to the algorithm that, although not perfect, ameliorates the issue for the vast majority of such cases. A separate issue is that as the number of overlapping detections increases, the number of matches to be considered increases at an alarming rate, requiring procedural adjustments to ensure that the cross-matching finishes within a Hubble time. We intend to make the tool available as a general purpose cross-match engine for calculating match probabilities between sources in multiple catalogs simultaneously.
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