The Calibration of Luminosity Criteria

Abstract

Attention is drawn to important systematic effects in the calibration procedure due to the accidental errors in the measured luminosity criteria. The present state of the luminosity calibrations in the MK system is reviewed with reference to recent work based on proper motions and radial velocities, and on trigonometric parallaxes, resulting in evidence for corrections of about −0.4 mag. for the K0–K5, III stars. Brief reference is made to the developments with regard to the Mv(K) system.The present report summarizes the principal elements of the review presented at the symposium.