An HI Survey of the Bootes Void. I. The Data

We present the results of a neutral hydrogen survey of the Bootes void carried out with the VLA in D-array. The survey covers $sim 1100$ Mpc$^{3}$, about 1% of the volume of the void as defined by Kirshner etal 1987. We observed 24 fields, centered on known void galaxies; 16 of these were detected in HI. Eighteen uncataloged companion galaxies were discovered directly in the HI line at distances of $45sec$ to $14.5min$ from the target galaxies. We also present the results of follow-up optical imaging observations and discovery of one additional Bootes void galaxy, found through spectroscopy of a number of apparent companions to known void members. Our angular resolution is $sim 1min$ (45 kpc) footnote{Throughout this paper, we have assumed ${H_{0}}$ = ${ m 100,km,s^{-1}Mpc^{-1}}$.}, each field has a size of $sim 1deg$ (2.7 Mpc). The detected HI masses range from $8 imes 10^{8}$ to $1 imes 10^{10} msol$. Typically our $2sigma$ HI column density sensitivity is $2 imes 10^{19} { m cm^{-2}}$. The radio and optical data are analyzed and discussed in the following companion article (Paper~2, Szomoru, van Gorkom, Gregg and Strauss 1996).Comment: Latex file of The postscript version of the complete paper (1.1 Mb in gzipped format) including all the figures can be retrieved from http://www.astro.rug.nl:80/~secr/ To appear in the February 1996 issue of the Astronomical Journa