LUCIFERS, A PHOTOELECTRIC RADIAL-VELOCITY SPECTROMETER

A spectrometer dedicated to the measurement of stellar radial velociti es has been developed at the University of Canterbury and the Mt John University Observatory. The spectrometer scans a spectrum from the Obs ervatory's 1-metre McLellan reflecting telescope and fibre-fed echelle with an oscillating mask having 2447 rectangular slots representing a bsorption lines in the spectrum of the star ct Centauri A covered by t he wavelength range 397 to 570 nm in orders 40 to 58 of the spectrogra ph and measures the light passing through the mask as a function of ma sk position. A dedicated computer constructs a cross-correlation funct ion to which a Gaussian distribution function is fitted. The differenc e between the radial velocities of a star and a zero-velocity referenc e spectrum provided by a hollow-cathode iron emission lamp is calculat ed from the Gaussian parameters. The sources of random error in the sy stem are discussed and its magnitude for stars of spectral types FO to M3.5 is estimated. Systematic errors in the system are also discussed .