Mon. Not. R. Astron. Soc., 400, 743-765 (2009/December-1)
A blind HI survey in the Canes Venatici region.
KOVAC K., OOSTERLOO T.A. and VAN DER HULST J.M.
Abstract (from CDS):
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 106 and 108M☉) 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 deg2 and a range in velocity from about -450 to about 1330km/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 NGC 4822, and it has been already detected in previous Hi studies. 19 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 per cent of the detections have profile widths less than 130km/s, and they 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.