1 trigonometric parallaxes william van altena yale university basic astrometric methods yale...
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1
Trigonometric Parallaxes
William van Altena
Yale UniversityBasic Astrometric Methods
Yale University
July 18-22, 2005
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The Geometry
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More Geometry
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Yes, the Earth moves around the Sun!
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Parallactic motion in Ecliptic Coords
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The Parallactic Ellipse
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Parallax in RA and Dec
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Parallax in RA and Dec (cont.)
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Observational Techniques
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Maximum Parallax Factor
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Ecliptic Latitude Dependence
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Determination of π & µ
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Typical analysis “pipeline”
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Typical analysis “pipeline” (cont.)
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Solving for a single π
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Errors and weights
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Errors and weights (cont.)
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Errors and weights (cont.)
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Reference stars
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Atmospheric Refraction
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Effective wavelength of each star
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Refraction versus star color
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Correction to Absolute π
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Systematic errors
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External error sources
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Deriving external errors
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Parallax ProgramsCatalog Date #stars mas) Comments
YPC 1995 8112 ±15 mas Cat. of all π through 1995
USNO pg To 1992 ~1000 ±2.5 mas Photographic parallaxes
USNO ccd From ‘92 ~150 ±0.5 mas CCD parallaxes
Nstars & GB Current 100? ± 2 mas Southern π programs
Hipparcos 1997 105 ±1 mas First modern survey
HST FGS 1995-2010? 100? ±0.5 mas A few important stars
SIM 2016? 103 ±4 µas Critical targets & exoplanets
Gaia 2016? 109 ±10µas “Ultimate” modern survey
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References for Parallax Programs
Catalog Comments References
YPC Cat. of all π through 1995 van Altena, Lee & Hoffleit 1995
USNO pg Photographic parallaxes Dahn, Harrington, et al
USNO ccd CCD parallaxes Monet, Dahn, et al. AJ,103,638,1992
Nstars & GB Southern π programs Henry, Jao, Ianna, Costa, Mendez, …
Hipparcos First modern survey ESO
HST FGS A few important stars Benedict & HST FGS Team
SIM Critical targets & Exo-planets NASA/JPL
Gaia “Ultimate” modern survey ESO