  A collection of spectral energy distributions (SEDs) is available in the
Hubble Space Telescope (HST) CALSPEC database that is based on calculated model
atmospheres for pure hydrogen white dwarfs (WDs). A much larger set (~100,000)
of UV SEDs covering the range (1150-3350A) with somewhat lower quality are
available in the IUE database. IUE low-dispersion flux distributions are
compared with CALSPEC to provide a correction that places IUE fluxes on the
CALSPEC scale. While IUE observations are repeatable to only 4-10% in regions
of good sensitivity, the average flux corrections have a precision of 2-3%. Our
re-calibration places the IUE flux scale on the current UV reference standard
and is relevant for any project based on IUE archival data, including our
planned comparison of GALEX to the corrected IUE fluxes. IUE SEDs may be used
to plan observations and cross-calibrate data from future missions, so the IUE
flux calibration must be consistent with HST instrumental calibrations to the
best possible precision.
