Sky Brightness Evaluation at Concordia Station, Dome C, Antarctica, for Ground-Based Observations of the Solar Corona.

The evaluation of sky characteristics plays a fundamental role for many astrophysical experiments and ground-based observations. In solar physics, the main requirement for such observations is a very low sky brightness value, less than of the solar disk brightness ( ). Few places match such a requirement for ground-based, out-of-eclipse coronagraphic measurements.

Optical design of a high-spatial-resolution extreme-ultraviolet spectroheliograph for the transition region.

A spectroheliograph dedicated to the observation of the solar disk in the extreme-ultraviolet OV spectral line at 62.97 nm is described. As demonstrated in the Skylab SO-82A spectroheliograph [Appl.