The Photographic Detection of Faint Lines In Stellar Spectra

Abstract

When analysing photographed spectra of"stars, it is frequently necessary to detect and to measure absorption or emission lines which are concealed by the graininess of a single negative. Techniques are described by which the data of many negatives of one star, or of several similar stars, can be numerically combined. The result is that while the effect of grain diminishes, genuine spectral features of the stars are preserved and consequently become measurable.