Effective temperatures of late-type stars - The field giants from K0 to M6

Angular diameters from lunar occultation are combined with infrared photometry to determine effective temperatures for K0-M6 giants. The relations between effective temperature and color temperature, MK spectral type, V-K color, and I(104)-L color are derived. The principal result is a general increase in effective temperature for the cooler spectral types compared to previous calibrations. Throughout the temperature range studied, excellent agreement is obtained with recent model atmosphere computations.