The slope of the late giants sequence in some two-colour diagrams differs significantly from the slope of other sequences and from the slope of the interstellar reddening lines. This circumstance makes M giants an indispensable source of data on both stellar parameters and interstellar extinction. The aim of the present study is to find suitable two-colour diagrams for the parameterisation of M-giants and to develop a parameterisation technique from the observed photometry. The work results in a tool for determining the intrinsic colour, spectral type and interstellar extinction parameters for the WBVR and ugriz photometric systems.
Zakharov et al. (Wed,) studied this question.