NIBLES - an HI census of stellar mass selected SDSS galaxies: I. The
  Nan\c{c}ay HI survey
  To investigate galaxy properties as a function of their total stellar mass,
we obtained 21cm HI line observations at the 100-m class Nan\c{c}ay Radio
Telescope of 2839 galaxies from the Sloan Digital Sky Survey (SDSS) in the
Local Volume (900<cz<12,000 km/s), dubbed the Nan\c{c}ay Interstellar Baryons
Legacy Extragalactic Survey (NIBLES) sample. They were selected evenly over
their entire range of absolute SDSS z-band magnitudes (-13.5 to -24 mag), which
were used as a proxy for their stellar masses. Here, a first, global
presentation of the observations and basic results is given, their further
analysis will be presented in other papers in this series. The galaxies were
selected based on their properties, as listed in SDSS DR5. Comparing this
photometry to their total HI masses, we noted that, for a few percent, the SDSS
magnitudes appeared severely misunderestimated, as confirmed by our
re-measurements for selected objects. Although using the later DR9 results
eliminated this problem in most cases, 384 still required manual photometric
source selection. Usable HI spectra were obtained for 2600 galaxies, of which
1733 (67%) were clearly detected and 174 (7%) marginally. The spectra for 241
other observed galaxies could not be used for further analysis owing to
problems with either the HI or the SDSS data. We reached the target number of
about 150 sources per half-magnitude bin over the Mz range -16.5 to -23 mag.
Down to -21 mag the overall detection rate is rather constant at the ~75% level
but it starts to decline steadily towards the 30% level at -23 mag. Making
regression fits by comparing total HI and stellar masses for our sample,
including our conservatively estimated HI upper limits for non-detections, we
find the relationship log(M_HI/M*) = -0.59 log(M*) + 5.05, which lies
significantly below the relationship found in the M_HI/M* - M* plane when only
using HI detections.
