Isophotal Contour Maps of Sunspots

Abstract

Maps are presented showing the complex intensity distribution in the umbrae and penumbrae of two large spots. The umbral isophotes show several points of minimum intensity, in one of which the temperature is some 500 oK below the average for the umbra. This extra-dark region, or "core", is only a few seconds of arc in diameter and is located near one end of the umbra.