||Cross-matching Within the Chandra Source Catalog
||521, Astronomical Data Analysis Software and Systems XXVI
||Rots, A.; Burke, D.; Civano, F.; Hain, R.; Nguyen, D.
||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
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