Photoelectric measurements of light-changes in the comet
Arend-Roland were made from April 22nd to May 6th 1957. From the measurements the absolute magnitude of the comet for the spectral range of 4000 A, m0 = 6.73. n = 3.48 was established. The curve of the light-changes was compared with the incidence of chromospherical flares in this period. Traces of a possible connection of the alterations in the comet´s brightness with changes in the solar activity were recorded.
From photoeIectric photometry at our 90-cm telescope we derived continuum and emlssion band fluxes within the bandpasses of the.standard IHW filters. These data were converted to give product ion rates for CN, C3, C2 , and soIids. The observations cover the range of pre-periheIion distances from'^2.1 AU to 1.1 AU and include one post-periheI ion measurement at 1.7 AU. The product ion rates of the gaseous components show a strong dependence on heliocentric distance. The result is compared with the behaviour of other comets and theoretical considerations. The dependence is less steep for the solids. This may be due to relatively pronounced backscattering of the grains. During one pre-perihe ion night (r = 1.5 AU) intensity profiles along three sections through the coma of P/Halley were measured. Compared with the Haser model the
profiles show a global anisotropy of the coma and possibly local structure.