The GALEX Ultraviolet Virgo Cluster Survey (GUViCS). V. Ultraviolet
  diffuse emission and cirrus properties in the Virgo cluster direction
  CONTEXT: The Virgo direction has been observed at many wavelengths in the
recent years, in particular in the ultraviolet with GALEX. The far ultraviolet
(FUV) diffuse light detected by GALEX bears interesting information on the
large scale distribution of Galactic dust, owing to the GALEX FUV band
sensitivity and resolution. AIMS: We aim to characterise the ultraviolet large
scale distribution of diffuse emission in the Virgo direction. A map of this
emission may become useful for various studies by identifying regions where
dust affects observations by either scattering light or absorbing radiation.
METHODS: We construct mosaics of the FUV and near ultraviolet diffuse emission
over a large sky region (RA 12 to 13 hours, DEC 0 to 20 degrees) surrounding
the Virgo cluster, using all the GALEX available data in the area. We test for
the first time the utilisation of the FUV diffuse light as a Galactic
extinction E(B-V) tracer. RESULTS: The FUV diffuse light scattered on cirrus
reveals details in their geometry. Despite a large dispersion, the FUV diffuse
light correlates roughly with other Galactic dust tracers (coming from IRAS,
Herschel, Planck), offering an opportunity to use the FUV emission to locate
them in future studies with a better resolution (about 5 arcsec native
resolution, 20 arcsec pixels maps presented in this paper) than several usual
tracers. Estimating the Galactic dust extinction on the basis of this emission
allows us to find a smaller dispersion in the NUV-i colour of background
galaxies at a given E(B-V)than with other tracers. The diffuse light mosaics
obtained in this work are made publicly available.
