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		| Paper: | 
		The XCat-DB: A Multi-wavelength View on the 2XMMi Catalogue | 
	 
	
		| Volume: | 
		411, Astronomical Data Analysis Software and Systems XVIII | 
	 
	
		| Page: | 
		466 | 
	 
	
		| Authors: | 
		Motch, C.; Michel, L.; Pineau, F.-X. | 
	 
	
	
		| Abstract: | 
		The XCat-DB hosts the newly-released 2XMMi catalogue together with many associated products such as X-ray images, spectra, time series and optical finding charts. One of its innovative features is to give access to crosscorrelations with ~ 200 archival catalogues. For the most important ones (SDSS R6, USNOB-1 and 2MASS), a specific likelihood ratio algorithm has been used to compute identification probabilities with entries in these catalogues. The XCat- DB is meant to be a “discovery tool” facilitating the identification of individual X-ray sources, thanks to locally-stored information and to direct VO access. Other important science goals are the creation of large source samples sharing homogeneous multi-wavelength properties and the search for interesting outliers. The current interface offers simple source selection and easy browsing through 2XMMi entries, associated data files and proposed X-ray source counterparts. Based on Saada, correlation information are stored in persistent relationships allowing fast query execution and navigation across the heterogeneous data sets. More complex queries mixing constraints on X-ray properties, on the existence or not of a possible counterpart in an archival catalogue and on the probability of association can also be made. The database can be accessed at XCat-DB1. | 
	 
	
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