Altair.
Abstract
A total of 443 observations of the Altair region were measured and reduced by the central overlap technique for positions, proper motions, and parallaxes of Altair and several reference stars. The relative parallax determined for Altair was 0.1911 + or  0.0037 arcsec. The centralstar residuals exhibit a possible perturbation suggestive of a lowmass companion. If an orbital analysis is included, the relative parallax of the Altair system becomes 0.1889 + or  0.0032 arcsec. Results from this study, along with recent measurements of Altair's angular diameter and flux distribution, yield values of 0.226 + or  0.022 and 1.023 + or  0.026, respectively, for the logarithms, to base 10, of the radius and luminosity in solar units.
 Publication:

The Astronomical Journal
 Pub Date:
 November 1978
 DOI:
 10.1086/112340
 Bibcode:
 1978AJ.....83.1455R
 Keywords:

 A Stars;
 Astrometry;
 Astronomical Photography;
 Data Reduction;
 Orbit Calculation;
 Parallax;
 Position (Location);
 Reference Stars;
 Stellar Luminosity;
 Stellar Motions;
 Astronomy;
 A Stars:Parallaxes;
 A Stars:Positions;
 A Stars:Proper Motions