A blind HI survey in the Canes Venatici region
  We have carried out a blind HI survey using the Westerbork Synthesis Radio
Telescope to make an inventory of objects with small HI masses (between 10^6
and 10^8 Msol) and to constrain the low-mass end of the HI mass function. The
survey has been conducted in a part of the volume containing the nearby Canes
Venatici groups of galaxies. The surveyed region covers an area on the sky of
about 86 square degrees and a range in velocity from about -450 to about 1330
km/s. We find 70 sources in the survey by applying an automated searching
algorithm. Two of the detections have not been catalogued previously, but they
can be assigned an optical counterpart, based on visual inspection of the
second generation Digital Sky Survey images. Only one of the HI detections is
without an optical counterpart. This object is detected in the vicinity of
NGC4822 and it has been already detected in previous HI studies. Nineteen of
the objects have been detected for the first time in the 21-cm emission line in
this survey. The distribution of the HI properties of our detections confirms
our ability to find low mass objects. 86% of the detections have profile widths
less than 130 km/s and can be considered dwarf galaxy candidates. The HI fluxes
measured imply that this survey goes about 10 times deeper than any previous
blind HI survey. The HI mass function and the optical properties of the
detected sources will be discussed in future papers.
