On the chromospheric observations at the 1962 eclipse

Abstract

A discussion is given of slitless spectrograms of the chromosphere obtained by an expedition of the High Altitude Observatory, Sacramento Peak Observatory, and National Bureau of Standards at the eclipse of 4–5 February 1962. The data which are considered consist of previously published line intensities plus continuum data presented here for the first time.

The data reduction procedure is briefly reviewed and a source of error introduced during the reduction is described. The error can possibly affect many of the reported line intensities.

Comparison of the 1962 observations with the HAO data from the 1952 eclipse indicates that the previously suggested factor-of-two decrease in the earlier data should be modified to a wavelength-dependent correction: a decrease by a factor of three or four at the high Balmer lines, a decrease by a factor of two at λ 4700 A, no change at Hα, and an increase by a factor of about 1.5 at the Paschen lines. The observed Balmer-to-Paschen line intensity ratios are therefore in the theoretically acceptable range, in contrast to the 1952 results. The height gradients of the Balmer line intensities agree reasonably well although the 1962 data tend to curve downward relative to a simple exponential distribution.