Determining the Absolute Astrometric Error in Chandra Source Catalog Positions

Abstract

Although relative errors can readily be calculated, the absolute astrometric accuracy of the source positions in the Chandra Source Catalog (CSC), Version 1.0, is a priori unknown. However, the cross-match with stellar objects from the Sloan Digital Sky Survey (SDSS) offers the opportunity to compare the apparent separations of the cross-matched pairs with the formally calculated errors. The analysis of these data allowed us to derive a value of 0.16" for the residual absolute astrometric error in CSC positions. This error will be added to the published position errors in the CSC from now on, starting with CSC, Version 1.1.

18 pages, 6 figures, accepted for publication in ApJSuppl

References in corpus (6)

• The Sloan Digital Sky Survey: Technical Summary
• The Seventh Data Release of the Sloan Digital Sky Survey
• The Chandra Source Catalog
• Probabilistic Cross-Identification of Astronomical Sources
• GALEX-SDSS Catalogs for Statistical Studies
• Cross-Identification Performance from Simulated Detections: GALEX and SDSS

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