Radial Velocities from CCD Detectors
TL;DRAbstract
The technique of measuring radial velocities by comparison of an object spectrum of unknown velocity to that of a template or mask spectrum of known velocity is well established. An analog device of this nature was developed by Griffin (1967), using a photomultiplier and mechanical mask to judge the degree of correlation between two spectra as a function of Doppler shift. This instrument was a large step forward in speed and efficiency, but suffered a low throughput due to a mask transmittance of about 10%. Digital cross-correlation techniques soon evolved using either digitized data from photographic plates (Simkin 1974) or data obtained directly in digital form (Da Costa et al. 1977, Tonry and Davis 1979). These methods have the advantage of preserving the actual spectrum of the object from which other quantities can be derived. The Fourier methods used in these studies are also used to derive the Doppler broadening of the source.
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The technique of measuring radial velocities by comparison of an object spectrum of unknown velocity to that of a template or mask spectrum of known velocity is well established. An analog device of this nature was developed by Griffin (1967), using a photomultiplier and mechanical mask to judge the degree of correlation between two spectra as a function of Doppler shift. This instrument was a large step forward in speed and efficiency, but suffered a low throughput due to a mask transmittance of about 10%. Digital cross-correlation techniques soon evolved using either digitized data from photographic plates (Simkin 1974) or data obtained directly in digital form (Da Costa et al. 1977, Tonry and Davis 1979). These methods have the advantage of preserving the actual spectrum of the object from which other quantities can be derived. The Fourier methods used in these studies are also used to derive the Doppler broadening of the source.
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