White Dwarf based evaluation of the GALEX absolute calibration
Abstract
This paper describes a revised photometric calibration of the \emph{Galaxy Evolution Explorer} magnitudes, based on measurements of DA white dwarfs. The photometric magnitudes of white dwarfs measured by \emph{GALEX} are compared to predicted magnitudes based on independent spectroscopic data (108 stars) and alternately to \emph{IUE} UV fluxes of the white dwarfs (218 stars). The results demonstrate a significant non-linear correlation and small offset between archived \emph{GALEX} fluxes and observed and predicted UV fluxes for our sample. The primary source of non-linearity may be due to detector dead time corrections for brighter stars, but it should be noted that there was a predicted non-linearity in the fainter stars as well. Sample expressions are derived which 'correct' observed \emph{GALEX} magnitudes to an absolute magnitude scale that is linear with respect, and directly related, to the \emph{Hubble Space Telescope} photometric scale. These corrections should be valid for stars dimmer than magnitudes 9.3 and 10.5 in the NUV and FUV respectively, and brighter than magnitude 17.5 in both
Keywords
Cite
@article{arxiv.1312.3882,
title = {White Dwarf based evaluation of the GALEX absolute calibration},
author = {L Camarota and J B Holberg},
journal= {arXiv preprint arXiv:1312.3882},
year = {2015}
}
Comments
Will be published in MNRAS. 13 pages, 6 figures, 4 tables, two of the tables are abridges; full versions available at MNRAS