A determination of the space density and birth rate of hydrogen-line
  (DA) white dwarfs in the Galactic Plane, based on the UVEX survey
  We present a determination of the average space density and birth rate of
hydrogen-line (DA) white dwarfs within a radius of 1 kpc around the Sun, based
on an observational sample of 360 candidate white dwarfs with g<19.5 and
(g-r)<0.4, selected from the UV-excess Survey of the Northern Galactic Plane
(UVEX), in combination with a theoretical white dwarf population that has been
constructed to simulate the observations, including the effects of reddening
and observational selection effects. The main uncertainty in the derivation of
the white dwarf space density and current birth rate lies in the absolute
photometric calibration and the photometric scatter of the observational data,
which influences the classification method on colours, the completeness and the
pollution. Corrections for these effects are applied. We derive an average
space density of hydrogen-line (DA) white dwarfs with T_eff > 10,000K
(M_V<12.2) of (3.8 +/- 1.1) x 1e-4 pc^-3, and an average DA white dwarf birth
rate over the last 7e7 years of (5.4 + 1.5) x 1e-13 pc^-3 yr^-1. Additionally,
we show that many estimates of the white dwarf space density from different
studies are consistent with each other, and with our determination here.
