Rocket observation of the EUV images of a solar flare and active regions

Abstract

Images of a flare and active regions were obtained in the extreme ultraviolet emission lines such as CIII 977 A, Ne VIII 770 A, and HI Lβ, and hydrogen Lyman continua with a spatial resolution of less than ten seconds of arc together with one-dimensional scanning at 1650 A. A microchannel plate was used as a detector, and pointing accuracy was, for about half of the observation time, around 0.5 arc sec. The relationship between the shape of the flare and the structure of the photospheric magnetic field is discussed. A map of the electron temperature distribution derived from the intensity ratio of the Lyman continua at 880 A and 815 A showed a lower temperature in regions of higher activity. A very small geometrical thickness of 50–500 m in the C III emitting region of the flare was found. And the layer emitting the continuum in 1650 A is shown to be at a temperature of 5300 K in the flare and 4700 K in active regions.