Red supergiants in the southern Milky Way. I - Search and classification techniques

Abstract

A detailed description of a continuing survey for distant, cool supergiants near the Galactic plane in the southern hemisphere is presented. Candidate stars are found on near-IR objective-prism plates, and confirming observations are made with near-IR narrowband photometry and medium-resolution CCD spectroscopy. The fluxes of 36 southern and equatorial standard stars for the eight-color narrowband system are given. The way in which stars are classified in temperature and luminosity type, and the way the photometry is used to derive distances and reddening are shown. Plate centers of the near-IR survey, properties of interference filters, fluxes of faint standard stars, and extinction coefficients for Cerro Tololo are presented.