Presentation on theme: "Magellanic Clouds Exploration. Motivation VO tools enable quick comparison of catalogs: position, photometry, proper motion, when available Cross match."— Presentation transcript:
Motivation VO tools enable quick comparison of catalogs: position, photometry, proper motion, when available Cross match of Photometric Catalogs with NVO-compatible surveys Assess astrometric and photometric quality when cross-matching databases with different qualities –Good astrometry but bad photometry matched to not so good astrometry but good photometry
Concept Cross correlate published catalogs (TABULARSKYSERVICE) with USNOB, GSC, 2MASS in the Magellanic Clouds By comparison of data, evaluate the reliability of cross matching for proper motion studies of selected stellar populations –Is XMATCH sufficient to safely cross-match extended databases, or is more sophisticated analysis needed?
Demers Photometry USNO Photometry Right Ascension Declination Demers IC catalog USNOB
USNOB: lots of stars with null p.m. in the south –Quantization of p.m.: 2,4,6,8,… mas/yr No p.m. data should be blank or p.m.>>0 P.M. RA P.M. DEC
We want more … but Demers IC GSC2.2 : failed –Query area too large, too many stars 5K rows limitation in Simple Query:
Right Ascension Declination Right Ascension 5000 Rows Limit in XMatch 2dF USNOB, rad=240
Conclusions Promising Idea Ability to draw conclusions limited by statistics and available catalogs Difficulties : importing MyData + 5K rows Richer Catalogs Needed –UCAC2, Tycho-2, SPM3, etc. –Catalogs of the future More Functionality needed –5k row limit is restrictive Good news: this limit to be lifted