Ripple correction and absolute calibration for final archive IUE high resolution spectra

Abstract

We report a detailed study about the ripple correction and absolute calibration of IUE high resolution spectra processed with NEWSIPS (i.e. the IUE Final Archive processing scheme). The analisis, based on very many spectra obtained with the SWP, LWP and LWR cameras, shows that the empirical positions of the blaze peaks vary in a way which does not depend only on the spectrograph's optics, but also on the camera's spatial response. This latter has been successfully parametrized as a function of the camera head temperature for the SWP camera and of the observing date for the LWP and LWR cameras. The performance of the ripple correction algorithms so obtained represent an important improvement over the ones adopted for IUESIPS. The ripple corrected high resolution spectra were then used to derive a new high resolution absolute calibration, which is accurate to within 3-4%, all over the spectral range covered by the IUE cameras.