The extraction of highly distorted spectra

Abstract

Digital spectra of point sources can be extracted with maximum signal-to-noise ratio by applying appropriate weights across the profile of the object. The first stage in computing these weights involves determination of the fraction of the flux of the object which falls into each pixel. The published methods differ at this stage, and none can cope with some commonly available types of data. An improved method for fitting the object profile is presented, which is particularly suited to the extraction of tilted and distorted spectra, as produced by data taken with cross dispersers and image tubes.