Cores in IR Dark Clouds for 300<=l<=330

They all lie in the range l=300-330{deg} and |b|<=1{deg}. Of these, only 1205 were seen in emission in the far-IR (250-500um) by Herschel (we call these 'Herschel-bright' clouds).

It is predicted that a dense cloud will not only be seen in absorption in the mid-IR, but will also be seen in emission in the far-IR at the longest Herschel wavebands (250-500um). If a region is dark at all wavelengths throughout the mid-IR and far-IR, then it is most likely to be simply a region of lower background IR emission (a 'hole in the sky'). Hence, it appears that previous surveys, based on Spitzer and other mid-IR data alone, may have overestimated the total IRDC population by a factor of ~2.