CN PHOTOMETRY OF COMET LEVY-1990XX

The results of photoelectric photometry with the narrowband CN and C-3 MW interference filters are presented. The observations were carried out with a set of diaphragms of different radii. The dust component of the cometary spectrum was not observed. Thus the flux in the C-3 filt er was treated as the upper limit for the dust component in the UV par t of the spectrum. The raw flux observed in the CN filter makes the up per limit and after subtraction of the C-3 flux makes the lower limit for pure CN radical flux. These limits were converted into the CN prod uction rates according to the classical Haser model and the difference s between them are smaller than 20%. The dependence of the production rate on heliocentric distance in the range of 1.7-1.3 AU is presented. (C) 1995 Academic Press, Inc.