Astron. Astrophys. Suppl. Ser. 139, 183-197

The IUE INES System: Improved data extraction procedures for IUE

P.M. Rodríguez-Pascual¹ - R. González-Riestra² - N. Schartel³ - W. Wamsteker⁴

Send offprint request: P.M. Rodríguez-Pascual

Correspondence to: p_miguel.rodriguez@fis.cie.uem.es

1 - Departamento de Física, Universidad Europea de Madrid, C/Tajo S/N, 28670 Villaviciosa de Odón, Spain
2 - LAEFF, P.O. Box 50727, 28080 Madrid, Spain
3 - ESA - XMM SOC, P.O. Box 50727, 28080 Madrid, Spain
4 - ESA - IUE Observatory, P.O. Box 50727, 28080 Madrid, Spain

Received March 1; accepted June 28, 1999

Abstract:

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 implementation to produce the NEWSIPS output products (extracted spectra) are discussed, and the procedures implemented in INES to solve these problems are outlined. The more relevant modifications are: 1) the use of a new noise model, 2) a more accurate representation of the spatial profile of the spectrum and 3) a more reliable determination of the background. The INES extraction also includes a correction for the contamination by solar light in long wavelength spectra. Examples showing the improvements obtained in INES with respect to SWET are described. Finally, the linearity and repeatability characteristics of INES data are evaluated and the validity of the errors provided in the extraction is discussed.

Key words: methods: data analysis -- space vehicles -- techniques: image processing -- ultraviolet: general