A complete 12CO 2-1 map of M51 with HERA

The nearby, almost face-on, and interacting galaxy M51 offers an excellent opportunity to study the distribution of molecular gas and the mechanisms governing the star formation rate. We have created a complete map of M51 in 12CO 2-1 at a resolution of 11 arcsec corresponding to 450 kpc using HERA at the IRAM-30m telescope. In Schuster et al. (2006) we have combined these data with maps of HI and the radio-continuum to study the star formation efficiency, the local Schmidt law, and Toomre stability of the disk in radial averages out to radii of 12 kpc. Here, we also discuss the distribution of giant molecular associations and its mass spectrum, in comparison with similar studies in the literature.