8.3.4 Checks Against Other Calibrations

  A check of the SWP high-dispersion wavelength calibration was made against the Copernicus satellite wavelength system for the standard B0.2 $\tau$ Scorpii with representative large-aperture images. This check showed a zeropoint offset of -4 km/s with respect to the Copernicus system for typical images; no trend with wavelength was found. The estimated errors in the IUE wavelengths as measured from these $\tau$ Scorpii observations were ±5 km/s per line.