Absolute magnitudes are derived from the spectral type or trigonometric
parallax. For dwarfs, it can also be computed from the 
color index.
Files containing stellar parameter data reside in oyster/starbase.
Extensive photometric data is found in files spec_par.X, where X
signifies the luminosity classes for dwarfs, giants, and supergiants,
V, III, Iab, respectively. For subgiants, brightgiants, and the subclasses
of the supergiants, limited data is in files spec_MV.IV,
spec_MV.II, spec_MV.Ia, spec_MV.Iab, spec_MV.Ib.
pmv_dwarfsDwarfs only; reads BV_MV.dwarfs.
pmv_stars All spectral types.
tmv_stars Use trigonometric parallax.