An automated technique for locating metal-deficient red giants from objective-prism spectra

A semi-automated technique designed to locate metal-weak G and K giants from objective-prism spectra in combination with temperature information from direct plates is described. An accurate wavelength calibration of the spectra made it possible to measure abundance using a line-strength index based on Ca II H and K as a function of color. Criteria based on spectral features between 3500 and 5300 A are described which enable metal-weak giant candidates to be isolated from foreground dwarfs. The technique has been used to locate metal-weak giants in several Galactic fields. 39 refs