The IUE INES System: Improved data extraction procedures for IUE

We present the extraction and processing of the IUE Low Dispersion spectra within the framework of the ESA \IUE Newly Extracted Spectra" (INES) System. Weak points of SWET, the optimal extraction imple- mentation to produce the NEWSIPS output products (extracted spectra) are discussed, and the procedures im- plemented in INES to solve these problems are outlined. The more relevant modications are: 1) the use of a new noise model, 2) a more accurate representation of the spa- tial prole of the spectrum and 3) a more reliable deter- mination of the background. The INES extraction also includes a correction for the contamination by solar light in long wavelength spectra. Examples showing the im- provements obtained in INES with respect to SWET are described. Finally, the linearity and repeatability charac- teristics of INES data are evaluated and the validity of the errors provided in the extraction is discussed.