Optional stellar data

In addition to the essential stellar data given in the previous subsection, it can be very useful to include supplemental information. For example, a program devoted to nearby dwarfs or low-luminosity stars would need proper motions to obtain accurate airmasses for some program stars. Spectral types are often adjoined to photometric catalog data. In many cases, rough photometric information that can aid in identification is available, such as a photographic magnitude from the HD. Finally, comments can be useful. These fields may be included in the table if the user wants them. They are described below the line in Table I.1.