Trigonometric parallaxes of 71 large proper motion stars

The trigonometric parallaxes of 71 stars with large proper motion were determined with the 26-inch refractor at Pulkovo Observatory. Relative parallaxes of the targets were derived using three or four separate series of observations (three or four pointings over 1.5 or 2 years for each one). Observations were performed over the period 2007–2011. We used from 5 to 20 reference stars per field. We applied a correction from relative to absolute parallax based on the photometric parallaxes of reference stars. The latter were estimated from infrared colours (J − Ks) and the reduced proper motions of reference stars, and from simulated colour–magnitude diagrams. The trigonometric parallaxes of 30 stars out of our 71 targets were previously unknown. In most cases, typical standard errors were 2 to 6 mas. The General Catalogue of Trigonometric Stellar Parallaxes contains data for 41 stars of our 71 targets. On the whole, Pulkovo parallaxes are in a good agreement with Yale results. The values of parallax differences are within −5 mas to +5 mas in 25 of the 41 stars. Considerable discrepancies are revealed in several cases. They may be explained by the presence of systematic errors in the data of both projects or by possible orbital motions not taken account for the case of double stars. The targets are mostly main sequence M-dwarfs closer than 50 pc. Three stars are white dwarfs and five stars are halo subdwarfs.