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2 years ago in Astrometry , Astronomy By Akshay R
Which star catalogue is currently the most accurate for astrometry?
I'm planning proper motion studies of star clusters and need the best available baseline data. I've used UCAC4 and Tycho-2 in the past, but I know major new surveys have been released. Is the Gaia Data Release 3 (DR3) now the unequivocal best choice for both accuracy and sky coverage, or are there niche cases where other catalogs might still be preferable?
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By Roopa K Answered 1 year ago
For nearly all modern applications, Gaia Data Release 3 (DR3) is the unequivocal foundation. I have seen it revolutionize proper motion studies, with uncertainties for bright stars at the ~0.02 mas/year level orders of magnitude better than pre-Gaia catalogs. Its completeness to G~20 magnitude is unmatched. The only exceptions might be for very bright stars where Gaia's detectors saturate, in which case you might cross-reference with Hipparcos (though Gaia's early DR4 may address this), or for specialized radio astrometry using VLBI. For your star cluster work, I would recommend starting all your analysis with Gaia DR3 as the reference frame. Just be mindful of its completeness limits in very dense cluster cores.
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