Photometry of the solar corona of March 7, 1970

Abstract

Isophotes obtained by equidensitometry techniques from four exposures of the March 7, 1970 corona are used for derivation of intensity distributions along the equator, poles, streamers and dark ' gaps ' in the visible corona. The distributions differ from the van de Hulst curves for a maximum corona. The Kodaikanal measures agree well with the NRL measures of the outer corona made from a rocket coronagraph and together provide data from 1.2R0 to 8-ORo along the solar equator. Radial intensity gradients for different position angles and €he LudendorfF parameters obtained, characterize this corona as typical of the solar maximum.