The database of nearby stars was taken from the SIMBAD Astronomical Database at the Centre de Données Astronomiques de Strasbourg.

Distances were determined either from parallaxes in SIMBAD or from spectroscopic parallaxes. The parallax sources were the Catalogue of Nearby Stars (Gliese and Jahreiss, editions 1969,1979,and 1991, called GJ in SIMBAD) or the PLX measurements in SIMBAD. The SIMBAD averages were used. Spectroscopic distances were calculated using the absolute magnitude calibration of Corbally and Garrison in The MK Process and Spectral Classification (R.F. Garrison ed., 1984). The absolute magnitudes were corrected by 0.2 magnitudes in multiple systems to allow for light from a secondary.

The GJ and PLX parallaxes were averaged for 879 stars. 734 stars had parallaxes only in the GJ source and 457 only in the PLX source. 1260 stars had only spectroscopic parallaxes. Four stars had GJ parallaxes smaller than 40 milliarcseconds, but these were used in a weighted average with the spectroscopic parallaxes. 23 stars were included using the PLX parallaxes in a similar procedure, and five stars were included from a weighted average of PLX, GJ, and spectroscopic distances.

All weighted averages were taken using the inverse of the squared error of the measurement as the weight. Spectroscopic distance errors were estimated as 25 percent in parallax.

The resulting list was checked for multiple stars. Distances were changed so that each system had a single distances. GJ and PLX parallaxes were preferred. If more than one star was listed, only the primary was kept. A few multiple systems (Alpha Centauri, 36 Ophiuchi, and HR 3018) had large enough separations that more than one star was kept.

Some were eliminated because their spectral types were probably erroneous. These were mostly those which differed in luminosity class from their listings in Sky Catalogue 2000.0. Parallaxes for Phi-5 Aurigae, Xi Scorpii, and HR 6237 were taken from the Yale Bright Star Catalogue. A parallax for BD+51 2402 (BY Draconis) was taken from AJ 88,684L (1983). Distances to L 143-23, LP 731-58, and G158-27 were from the 1996 Observer's Handbook (RASoc Canada, 1996) and the distance to L 372-58 was taken from the abstract of a talk given at the 1996 American Astronomical Society meeting.

-Harry Bowman
hlb6@cornell.edu

 

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