Granulation Near the Extreme Solar Limb

Abstract

Rosch (1957) found that on good photographs the photospheric granulation remains visible to within less than 10 sec of arc from the limb, and sometimes to less than 5 sec. Recently,however, these results have been contradicted by Edmonds (1960) who, on the basis of an examination of photographs obtained in "Project Stratoscope" (Schwarzschild 1959), finds that the granulation disappears almost completely at 6=75° (33 sec from the limb). Poor focus obliterates the last vestiges of the pattern closer to the limb; nevertheless, Edmonds concludes that the granulation disappears completely at 6=78° (21 sec from the limb). Since a determination of the distance from the limb at which the granulation disappears provides an estimate of the height of the top of the convection zone (Plaskett 1955; de Jager 1959), it is important to resolve this contradiction.