This class corresponds to a single valid variable star observation. Depending upon the source, some fields may be null. Some are not permitted to be null however and these are documented below.
For reference, here are the fields in the order they appear in the AAVSO download format:
JD(0), MAGNITUDE(1), UNCERTAINTY(2), HQ_UNCERTAINTY(3), BAND(4), OBSERVER_CODE(5), COMMENT_CODE(6), COMP_STAR_1(7), COMP_STAR_2(8), CHARTS(9), COMMENTS(10), TRANSFORMED(11), AIRMASS(12), VALFLAG(13), CMAG(14), KMAG(15), HJD(16), NAME(17), AFFILIATION(18), MTYPE(19), GROUP(20)
The simple format file has these fields:
JD MAGNITUDE [UNCERTAINTY] [OBSERVER_CODE] [VALFLAG]
When VStar was first developed, observation source plugins were not anticipated, but should have been. The additional details members permit other string-based information to be stored for an observation.