A&A Supplement series, Vol. 128, Mars I 1998, 409-416
Received January 24; accepted July 11, 1997
J.-P. De Cuyper and H. Hensberge
Send offprint request: J.-P. De Cuyper, Jean-Pierre.DeCuyper@oma.be
Royal Observatory of Belgium, Ringlaan 3, B-1180 Brussel, Belgium
Th-Ar lamps are commonly used as wavelength calibration units at moderately high spectral resolutions because of the richness of the Th spectrum in the visual. The inclusion of blended lines whose position is assumed to coincide with the laboratory wavelength of the principal component is shown to result in a calibration precision significantly worse than the intrinsic random noise limit. In order to avoid this degradation of the calibration, we present resolution-dependent Th-Ar wavelengths in the region 277 to for use at pixel-scales between and .
keywords: methods: data analysis; techniques: