The INES system IV. The IUE absolute flux scale

This paper deals with the definition of the input fluxes used for the calib ration of the IUE Final Archive. The method adopted consists in the determi nation of the shape of the detector's sensitivity curves using IUE low reso lution observations with model fluxes of the DA white dwarf G191-B2B. A sca le factor was then determined so that the IUE observations of some bright O AO-2 standards match the original measurements from Meade (1978) in the spe ctral region 2100-2300 Angstrom. The ultraviolet fluxes of six standard sta rs used as input for the Final Archive photometric calibration together wit h the model fluxes of G191-B2B normalized to the OAO-2 scale are given. A c omparison with the independent FOS calibration shows that the IUE flux scal e for the Ultraviolet is 7.2% lower. We consider this mainly to be caused b y the different normalization procedures. It is shown that the present flux calibration applies to spectra processed with the INES low resolution extr action software.