Hello, all. I'm trying to find an equation to determine a star's absolute magnitude in order to populate a table of stellar characteristics. Unfortunately, every formula I've run across requires a star's apparent magnitude and that requires knowing how far the star is from the observer. But, I need a general case formula. Basically, I have a star catalog, but many of the stars do not have a complete classification; perhaps they are listed as AIII, or M4.5, or, simply K. I'm going to provide a "best guess" at the full classification, by taking the parts that are known, and using the absolute magnitude to finesse the value. For example, suppose I have a star listed as A0 with an absolute magnitude of -3.36. By the data I already have, A0Ib has an absolute magnitude of -5.3, A0II has -3.4 and A0III has -0.3. Using averages to get the boundary between each entry - not perfect, but it's the best I have - I find that -3.36 falls within the boundary of -4.35 to -1.85 for an A0II star. So, I correct the incomplete entry to A0II. The problem is with star classes for which the table is incomplete; like classes C, S, WN, etc. I have the temperatures for these classes and their radii in solar units, but not their magnitudes. Any thoughts?