Three-Color Narrow-Band Photoelectric Photometery of Red Variables

Volume 21 number 1 (1992)

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Robert F. Wing

The Ohio State University, Columbus, OH 43210

Abstract

A photometric system consisting of three near-infrared interference filters and designed for studies of red variable stars is described. It represents a simplification of the writer's eight-color system of classification photometry and is intended for use with small telescopes and inexpensive instrumentation. The three filters measure an infrared magnitude, a color index, and an index of TiO band strength, which indicates the spectral type.  Measurements on this system should provide a valuable supplement to the visual light curves of red variable stars.  A set of standard stars is given which will enable observers to reduce their measurements to a system of absolute fluxes.  A procedure is described for deriving an index of TiO strength from the data and converting it to spectral type.