This data paper has presented the results of an extensive HI synthesis imaging survey with the WSRT of a well-defined complete equidistant sample of spiral galaxies in the nearby Ursa Major cluster. Figures B.1 and B.2 show a compilation of all the available HI maps. Individual galaxies are at their proper position on the sky but they are individually four times enlarged. Some galaxies had to be shifted to avoid overlapping maps. Rotation curves have been derived for most galaxies as well as detailed information on the kinematical state of the galaxy disks as indicated by the presence of global perturbations, warps, interactions and lopsidedness. Since the galaxies were not selected on the basis of their HI size or content, the quality of the kinematical data varies widely from galaxy to galaxy. Nevertheless, these data will be useful for an analysis of the statistical properties of the Tully-Fisher relation and the rotation curves may be decomposed into contributions from the main dynamical constituents like the stellar and gaseous disks, the bulge and the dark matter halo. These issues will be addressed in forthcoming papers.
Those who would like to use the rotation curves for their own purposes are advised not to take the rotation curves at face value but to check their validity against the actual data and to take notice of the comments provided on the atlas pages. It should be realized that the rotation curves presented here are derived from the kinematics of the HI gas which is assumed to be a tracer of a galaxy's potential. There are some caveats to be aware of like the projection effects of streaming motions and partially filled HI disks of edge-on systems.
Finally, optical long-slit spectroscopy is already available for nearly all galaxies in the sample. These high resolution optical rotation curves will be used to supplement the HI rotation curves in the inner regions, allowing for better decompositions and maximum-disk constraints.
Acknowledgements
The Westerbork Synthesis Radio Telescope is operated by the Netherlands Foundation for Research in Astronomy (NFRA/ASTRON), with financial support by The Netherlands Organization for Scientific Research (NWO). This research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, Caltech, under agreement with the National Aeronautics and Space Association. The results presented in this paper were obtained during MV's thesis research at the Kapteyn Institute of the University of Groningen, The Netherlands. This paper was finalized at the National Radio Astronomy Observatory which is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. This research has been supported by NATO Collaborative Research Grant 940271.
Copyright ESO 2001