VizieR Online Data Catalog: Luminous Stars in the Southern Milky Way (Stephenson+ 1971)

This Catalogue represents an extension to the entire Southern Milky Way of the objective-prism survey for intrinsically luminous stars in the Northern Milky Way <III/76> that was carried out jointly by the Hamburg and Warner and Swasey observatories.

The object has been to survey the Southern Milky Way with plates as similar as possible to the plates used for the Northern Milky Way, including similarity of limiting magnitude. To this end the objective prism that was used with the Warner and Swasey Schmidt telescope for the Northern survey was sent to Cerro Tololo, Chile, where it was used by Sanduleak to photograph the Southern Milky Way with the Schmidt telescope of the University of Michigan.

The survey was planned to have a minimum extent in galactic latitude of ±10deg. On each field three spectral plates were taken, all intended to have spectral widening near 0.2 mm. One blue-region (Kodak IIa-O) plate was given an exposure of 11 minutes, and another was double-exposed for 3 minutes and 10 seconds. A red plate (Kodak 103a-F plus Schott GG 14 filter) was also taken for the detection of any appreciable Hα emission, with three exposures nominally 9 minutes, 1 minute and 10 seconds. The dispersion is 580 Angstroems/mm at Hγ and about 1000 Angstroems/mm near Hα; a Michigan objective prism of 4deg angle, was used to obtain the Hα plates.

The spectral classification system is that discussed by Slettebak and Stock (1957) and Nassau and Stephenson (1960). An important result of the generally excellent quality of the new survey plates is that the ce stars (OB stars apparently having the Balmer continuum in emission) are easily recognised.

The magnitudes are based upon eye estimates of image density on the blue-region spectral plates, calibrated by published magnitude sequences, and are generally characterised by a probable error of 1/3 to 1/4 mag.

The equatorial coordinates for the stars have been derived from measurements of the objective-prism plates, using the SAO <I/131> catalogue for reference stars. The positions derived in this way are accurate to 1" to 2" of arc, providing spectral lines are visible for measurement. When spectral lines are not visible, the coordinate parallel to the spectral dispersion -- always the declination -- becomes 10" or somewhat more uncertain.

(2 data files).