Study of Spectroscopic Binaries with the Objective Prism Method

Frank Gieseking
1983 International Astronomical Union Colloquium  
The frequency distribution of SB's over apparent visual magnitude emerging from the catalogue of Batten et. al. (1978) shows a very steep decrease of the number of spectroscopically detected SB's already for such bright stars of magnitude 7. Considering the number of all stars in the individual magnitude intervals, we find a kind of completeness parameter of the spectroscopic surveys: If we scale it somewhat optimistically at 100% between 0 and 3 mag, we see a 50% decrease of the completeness
more » ... the completeness of our knowledge of stellar radial velocities already for stars fainter than 4.5 mag.This situation is mainly due to the fact that the measurement of radial velocities with conventional slit spectrographs is extremely laborious, requiring long exposure times at large telescopes for the exposure of only one spectrum at a time. –Therefore more efficient methods for radial velocity determinations of fainter stars are urgently needed.
doi:10.1017/s025292110000988x fatcat:drjdhoo5cjdpviahux5p4zlqc4