We present the results of the Nobeyama Radio Observatory (NRO) M 33 All Disk (30′ × 30′,or 7.3 kpc  ×  7.3 kpc) Survey of Giant Molecular Clouds (NRO MAGiC) based on12CO(J = 1–0) observations using the NRO 45-m telescope and12CO(J = 3–2) observations using the ASTE 10-m telescope.The spatial resolution of the resultant 12CO(J = 1–0) map is193, corresponding to 81 pc, which is sufficient to identify each Giant Molecular Cloud(GMC) in the disk. We found clumpy structures with a typical spatial scale of ~100 pc, corresponding to GMCs, and no diffuse, smoothly distributed componentof molecular gas at this sensitivity.

We obtained a map of the molecular fraction,fmol = ΣH2/(ΣHi + ΣH2),at a 100-pc resolution. This is the first fmol map covering anentire galaxy with a GMC-scale resolution. The correlation betweenfmol and gas surface density shows two distinct sequences.The presence of two correlation sequences can be explained by differences in metallicity,i.e., higher (~2-fold) metallicity in the central region(r <  1.5 kpc) than in the outer parts. Alternatively,differences in scale height can also account for the two sequences, i.e.,increased scale height toward the outer disk.