The Final Archive and Recalibration of the International Ultraviolet Explorer (IUE) Satellite

Since 1978 the International Ultraviolet Explorer (lUE) satellite has been acquiring the largest collection of astronomical ultraviolet spectra that will likely be obtained in the foreseeable future. The more than 100 000 spectral images, from which low and high dispersion spectra are extracted, include a very broad range of sources from solar system objects, stars of all types, interstellar and Galactic halo gas, normal galaxies, and active galactic nuclei. The Final Archive of lUE data will contain all of these spectral images and extracted spectra, reprocessed with uniform software and calibrations that enhance the quality of the data products. This paper summarizes the rationale for and content of the new processing algorithms, together with the calibration chronology of the lUE scientific instrument. Examples of spectra processed for the Final Archive demonstrate an increased signal-to-noise ratio of 10%-50% for low dispersion data and ∼100% or more for high dispersion data compared to the old processing scheme, the extension of the usable spectral range down to 1150 and up to 3400 Å, and the emergence of new spectral features from the fixed pattern noise that is now largely eliminated.