The solar corona on 31 July, 1981

Abstract

Various instruments were used to observe the solar corona near or at the time of total eclipse, 31 July, 1981. The High Altitude Observatory (HAO) coronal eclipse camera and the MK-III K-coronameter recorded the lower portions of the corona; the distribution of white light material above 3 R _⊙ was observed with the Naval Research Laboratory (NRL) satellite coronagraph on P78-1. These data sets are used to describe coronal structure and to identify coronal active regions. The polar coronal holes, as developed at this time in the solar cycle, were offset from the poles of rotation; both were seen displaced eastward on eclipse day. High latitude streamers appear in all three data sets, extending from the base of the corona outward to at least eight solar radii from Sun center. At least two transients were observed by the NRL experiment on the eclipse day, but it is likely that no transient was in progress during any observation along the eclipse path. A distribution of the white-light corona, derived from synoptic K-coronameter data, is given.