Ariel 5: a British triumph.

The Ariel 5 satellite has proven effective in measuring cosmic X-rays across a wide band of energy levels. Solid crystals are used to produce scintillations corresponding to X-rays of energies from 2 keV to 1 MeV. Two broad sets of experiments are built into the satellite. The first, or pointing set, is aligned with the satellite spin-axis and includes: a high energy scintillation counter, measuring X-rays between 30 keV and 1 MeV; a low energy scintillation counter, sensitive from 30 down to 2 keV; a proportional counter to locate the position of X-ray sources; and a Bragg spectrometer to analyze discrete X-ray packets emanating from specific elements. The second, or scanning set, is pointed orthogonally to the spin-axis and includes: two proportional counters to scan the sky around the satellite's equator, and an all-sky monitor with a resolution of one hour (rather than a few minutes). The scientific yield has thus far provided information on transient X-ray sources, established sources, and X-ray bursts.