PPT Slide
Fundamental Astronomy: Positions
Distances To Stars From Parallax
Present ground-based trigonometric parallaxes have probable errors of ?0.004”.
A parallax of 0.100” ? 0.004” has a 50% probability of being between 0.096”- 0.104”.
Accurate only to distances of about 100 pc
The Hipparcos satellite (ESA) has measured parallaxes of ~0.001”, giving accurate distances out to ~1000 pc (1 kpc)