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In order to monitor the various phenomena of comets, we continuously made the near-nucleus imaging observations of comets at National Astronomical Observatory, Mitaka. Here we report on the results of the observations of two spectacular comets. One is the analysis of photometry of C2emission images in the coma of comet Hyakutake (C/1996 B2)). By comparing the production rates of C2radicals with C2H2molecules, we conclude that the most C2radicals were originated from C2H2, while some of them might be produced from other parents. The second item is the analysis of the morphology of C2emission images in the coma of comet Hale–Bopp(C/1995 O1)). By applying a ringmasking technique, we detected asymmetrical distribution of the C2molecules. The results of these two comets might suggest that a portion of C2radicals were formed by the disintegration of the small organic dust grains, like the so-called CHON particles.