A photometric study of the Orion OB 1 association. I - Observational data. II - Photometric analysis

A catalog of observational data is presented for stars in the region of the young stellar association Orion OB 1. Photoelectric observations obtained in the uvby-beta and UBV systems are compiled along with previous photoelectric and spectroscopic data for all these stars as well as for several bright members of the association with available photometric indices. Mean weighted values are computed for the photometric data and summarized in tables expected to be reasonably complete for association members earlier than spectral type A0. Membership criteria are derived, and qualitative membership probabilities summarized, for the 526 stars in the final program. The analytical procedures are discussed for association stars of B, intermediate, and AF types. Effects of the nebular environment and various calibrations of Balmer-line and four-color indices are considered for the determination of absolute magnitudes for the B-type stars.