Positions and Proper Motions - North

Its main purpose is to provide a convenient, dense, and accurate net of astrometric reference stars that represents the new IAU (1976) coordinate system on the sky. The mean epoch is near 1931.

The average mean errors of the positions and proper motions are 0.27" and 0.43"/cen. On the average six measured positions are available per star; 1064 stars do not have sufficient redundancies to resolve discrepancies. In addition to the positions and proper motions, the PPM (North) contains the BD number, the magnitude, the spectral type, the number of positions included, the mean error of each component of the position and proper motion, the weighted mean epoch in each coordinate, the numbers in the SAO, HD, and AGK3 catalogs, and various standard notes.