SIMBAD references

The systematic, spectroscopic two-dimensional classification of the HD stars by N. H. is approximately three-quarters complete. Over 161,000 stars have been classified visually using 10° objective-prism plates (2 Å resolution) taken at CTIO with the Michigan Curtis Schmidt telescope. The published portion of this large, homogeneous database, taken from volumes 1-5 of the Michigan Spectral Catalogue (declination -90° to +5°), has been used to create an H-R diagram. The Hipparcos parallax measurements provide a large homogenous database, too. H-R diagrams of the HD stars found in both catalogs are produced for distances to 20, 50, 100, and 200 pc.