Two slitless Bragg spectrometers were successfully used on a Sun-pointed Skylark rocket flight (SL 304) on May 5, 1966, to measure the solar X-ray emission below 25 Å. The crystals were of potassium ...

IT seems very improbable that the bright line spectrum of the inner corona can be attributed to thermal excitation of the coronal matter. We may seek its cause in the process of photoelectric ...

A famous night-sky object has yielded a surprise: a narrow, bar-shaped cloud made of highly ionized iron. The discovery comes from a European team led by astronomers at University College London and ...