Magellanic Clouds Exploration

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

US

NO

Pho

tom

etry

Right Ascension

Dec

linat

ion

Demers IC catalog USNOB

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

. D

EC

Demers IC 2MASS

J

J - H

2dF + Rebeirot <=> USNOB

2dF + Rebeirot <=> USNOB

We want more … but

Demers IC GSC2.2 : failed– Query area too large, too many stars

• 5K rows limitation in Simple Query:

Right Ascension

Dec

linat

ion

Dec

linat

ion

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