## On the uncertainty of distances derived from parallax measurements
The problem of determining the distances and their uncertainties from the measurements of parallaxes has no straight forward solution. In contrast to Bayesian-like approaches, a direct approach is possible assuming that the probability density function (pdf) in relative distance is cut for negative distances. This gives an asymmetrical pdf which is difficult to use and overestimates variances. It is proposed to fit it by a Gaussian pdf which minimizes the deviation from the actual pdf for the central interval, and the weighted deviation from most of the pdf. The characteristics of this Gaussian is given as functions of the parallax and its rms.
This article contains no SIMBAD objects. ## Contents- 1. Introduction
- 2. Distance estimation and its pdf
- 3. A probability distribution function for distances
- 4. A Gaussian approximate pdf
- 5. Conclusions
- Acknowledgements
- References
© European Southern Observatory (ESO) 1998 Online publication: November 9, 1998 |