A LIQUID-FILTER CELL FOR TELESCOPE USE

Abstract

The availability of photocathodes with a broad range of spectral response extending from the ultraviolet continuously to the infrared (the S-l and S-20 surfaces, for example) makes photometry over such intervals possible with a single photomultiplier. However, many of the blue and violet filters ordinarily used in broad and intermediate bandwidth photometry have a non-trivial transparency for A>6000 Â, which constitutes a serious red leak when used with such detectors.