Transcript Trigonometric Parallaxes

Trigonometric Parallaxes
William van Altena
Yale University
Basic Astrometric Methods
Yale University
July 18-22, 2005
1
The Geometry
2
More Geometry
3
Yes, the Earth moves around the Sun!
4
Parallactic motion in Ecliptic
Coords
5
The Parallactic Ellipse
6
Parallax in RA and Dec
7
Parallax in RA and Dec (cont.)
8
Observational Techniques
9
Maximum Parallax Factor
10
Ecliptic Latitude Dependence
11
Determination of π & µ
12
Typical analysis “pipeline”
13
Typical analysis “pipeline”
(cont.)
14
Solving for a single π
15
Errors and weights
16
Errors and weights (cont.)
17
Errors and weights (cont.)
18
Reference stars
19
Atmospheric Refraction
20
Effective wavelength of each star
21
Refraction versus star color
22
Correction to Absolute π
23
Systematic errors
24
External error sources
25
Deriving external errors
26
Parallax Programs
Catalog
Date
#stars
s(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
27
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
28