Abstract from paper : The CALSPEC database of absolute spectral energy distributions (SEDs) from the Hubble Space Telescope (HST) is based on pure hydrogen model atmosphere calculations for three unreddened white dwarf (WD) stars and represents the current UV flux calibration standard with a precision approaching 1% for well observed stars. Following our previous work to correct IUE fluxes, this paper provides an average correction for the GALEX spectral database that places GALEX fluxes on the current CALSPEC scale. Our correction is derived by comparing GALEX spectroscopic flux distributions with CALSPEC and corrected IUE SEDs. This re-calibration is relevant for any project based on GALEX archival spectroscopic data, including UV or multi-wavelength analyses, correlating GALEX spectra with other existing or future databases, and planning of new observations. The re-calibration will be applied to our planned catalog of corrected GALEX SEDs.

Table 3 of Bohlin & Bianchi 2019. The corrections for GALEX spectra fluxes Flux correction coefficients to bring GALEX spectra on the HST UV scale (in 50 Å bins from 1300 - 3000 Å). GALEX spectrophotometry is repeatable to only 10-20% in regions of good sensitivity, the average flux correction presented by Bohlin \& Bianchi 2019 has a precision of about 3%.

Combined IUE spectra for the 18 GALEX matched stars used for re-calibration (in addition to CALSPEC standard stars): (these merged spectra can be referred as DOI http://dx.doi.org/10.17909/T9FQ2N , and are also available in MAST High-Level-Science-Products at galex-fluxcal ) File columns are: WAVELENGTH - Wavelength in vacuum in Angstroms. NET - The averaged net signal in linearized IUE Flux Number (FN) units per second. FLUX - The average flux in ergs cm-2 s-1 Angstrom-1. BKG - The background signal (same units as NET column). UNCERTAINTY - The formal, propagated uncertainty as the "error-in-the-mean" (same units as FLUX column). NPTS - The number of observations averaged. TIME - The total exposure time in seconds. RMS - The RMS scatter among the observations as a percent. Download merged spectra: hz4 sk196 hz21 stha190 bpm16274 l791-40 wd0416-55 g93-48 lb227 hz2 gd50 lds749b gd108 q1302-102 gd153 hg7-233 feige59 sk194