The INES system - II. Ripple correction and absolute calibration for IUE high resolution spectra

In this paper we document the results of the study which led to the ripple correction and absolute calibration algorithms applied to the high resoluti on spectra processed with the NEWSIPS software for the Final archive of the IUE Project. In this analysis, based on a very large number of spectral we find that both the It and alpha parameters (not only the former as previou sly believed) vary with order number. This fact, together with the finding that the central peaks of the blaze function vary also as a function of the THDA temperature (for the SWP camera) and of the date of observations (for the LWP and LWR cameras), makes the ripple correction algorithm more compl ex than previously considered but, at the same time, considerably more reli able. As for the high resolution absolute calibration, the method followed is similar to the one implemented in IUESIPS. The internal accuracy of the high resolution calibration is about 4%. We note that the ripple correction and absolute calibration algorithms here described apply also to IUE data processed and distributed with the INES system.