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.
15 sets of isophotae of the comet Arend-Roland are presented. They were obtained from photographs taken with the double astrograph of the Ondřejov Observatory. The method of reductions is briefly described. A list of 16 other plates of good or medium quality, not reduced here, is addied. The striking features of the comet´s appearance during the days April 27 to May 2 are quite briefly discussed. The isophotae describe the appearance of the comet on blue and panchromatic plates to a distance of 2°-3° from the head.