The Raffety Bands in Comets

Fourteen nuclear bands of unknown origin in the spectra of comets situated between A 3987 and X 4109 have been investigated in detail. Data compiled from determinations of the wave-lengths of these bands in twelve comets with slit-spectrographs have been used for this purpose. The wave-lengths correspond to those obtained in the labora- tory by C. W. Raffety for the spectrum of the presumably CH molecule. The agreement is not complete. Neither the `II - `II carbon system nor the cyanogen tail bands can be identified with the cometary bands. The variaiion in brightness of the bands, depending on the heliocentric distance of the comet, shows that they form at least two systems. The intensity-curves fall between that of the CH band X 4314 and the CIV band X 3883. It is shown that the edges of eleven bands can be represented tolerably well by the formula v= 24,335+71.0 n-o.in2. Assuming the final state of the molecule that of the violet and red cyanogen systems the formula become