Emission band and continuum photometry of Comet West (1975n)

The scale lengths of the CN and C2 molecules and their parents are derived based on Haser's model from drift scans across the coma of Comet West in the light of CN(0,0), C2(0,0) and the continuum around 5000 A. The analysis provides evidence to show that the CN molecules are produced by the dissociation of two species of parent molecules having entirely different lifetimes. A similar result is also obtained for the C2 molecules. The step scans of 1976 March 19.96, covering the spectral range 3700 to 5300 A and at five independent locations inside the coma show that there is an increase of reddening of the continuum, from the centre of the nucleus outwards. These provide evidence that the coarser particles are confined to the centre and the finer ones towards the periphery. A study of the radial distribution of CN, C3 and C2 molecules and of the dust particles shows that the C3 (4050 A) intensities fall most rapidly, compared to CN or C2. (author)