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The development of new algorithms and techniques for processing high dispersion IUE data for the creation of the Final Archive is nearly complete. The techniques are similar to those for low dispersion through the two-dimensional photometric correction step. However, the system provides an entirely new high-dispersion output product, a two-dimensional geometrically rectified image with the echelle orders horizontal to facilitate custom spectral extraction methods. Wavelengths are linearized within each order in this new image and small-scale distortions removed. The global background intensity level is modeled in two dimensions. The high-dispersion spectral data will be extracted with a weighted slit technique which includes not only the modeled background correction, but also an interorder overlap correction and an error estimate for each extracted point.
Results from processing high-dispersion data with the prototype system are presented. Improvements in the signal-to-noise ratio of the extracted data over the original processing are substantial, partially due to the elimination of over-sampling in the extraction and partially to the improved photometric correction and extraction technique.
This work has been supported under NASA contract NAS5-31230 to Computer Sciences Corporation.
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