Giant Molecular Clouds in the Outer Arm of the Galaxy.

Giant molecular clouds in the Outer Arm of the Galaxy comparable in size and mass to the largest clouds in the inner Galaxy between R ~ 3 kpc and the solar circle have been detected in a new CO survey along the galactic plane from l = 65degrees to 71degrees centered about b = +1degrees. These objects at R ~ 12kpc (for R sub o = 8.5 kpc) are under-luminous in CO; the N(H sub 2)/W sub (CO) ratio determined from either virial masses or the CO luminosity-line width relation is 5 +- 3 times that in the inner Galaxy.