The INES system

IV. The IUE absolute flux scale

¹ Laboratorio de Astrofísica Espacial y Física Fundamental, VILSPA, PO Box 50727, 28080 Madrid, Spain
² Istituto di Astrofisica Spaziale, CNR, Area di Ricerca Tor Vergata, Via del Fosso del Cavaliere 100, 00133 Roma, Italy
³ Dipartimento di Fisica E. Amaldi, Universitá degli Studi Roma Tre, Via della Vasca Navale 84, 00146 Roma, Italy
⁴ ESA-IUE Observatory, VILSPA, PO Box 50727, 28080 Madrid, Spain

Corresponding author: R. González-Riestra, ch@laeff.esa.es

Received: 15 February 2001
Accepted: 17 April 2001

Abstract

This paper deals with the definition of the input fluxes used for the calibration of the IUE Final Archive. The method adopted consists in the determination of the shape of the detector's sensitivity curves using IUE low resolution observations with model fluxes of the DA white dwarf G191-B2B. A scale factor was then determined so that the IUE observations of some bright OAO-2 standards match the original measurements from Meade ([CITE]) in the spectral region 2100-2300 Å. The ultraviolet fluxes of six standard stars used as input for the Final Archive photometric calibration together with the model fluxes of G191-B2B normalized to the OAO-2 scale are given. A comparison with the independent FOS calibration shows that the IUE flux scale for the Ultraviolet is 7.2% lower. We consider this mainly to be caused by the different normalization procedures. It is shown that the present flux calibration applies to spectra processed with the INES low resolution extraction software.