International Ultraviolet Explorer


International Ultraviolet Explorer:

see ultraviolet astronomyultraviolet astronomy,
study of celestial objects by means of the ultraviolet radiation they emit, in the wavelength range from about 90 to about 350 nanometers. Ultraviolet (UV) line spectrum measurements are used to discern the chemical composition, densities, and temperatures
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International Ultraviolet Explorer

(IUE) A satellite that is a joint project of NASA, ESA, and SERC (the UK's Scientific and Engineering Research Council) and was launched by NASA into an elliptical geosynchronous orbit on Jan. 26 1978. Its 45-cm Ritchey-Chrétien telescope focuses ultraviolet radiation on either of two echelle grating spectrographs providing about 0.01 nm spectral resolution; they operate in the wavelength range 115–190 nm and 180–320 nm. In addition lower resolution (about 0.6 nm) spectrographs are available for observations of faint sources. The satellite is controlled from ground stations in Maryland and Madrid by real-time data link, which permits operation in a manner similar to that of a ground-based observatory. In the 18 years of operation over 90 000 spectra were obtained on a wide variety of astronomical sources including planets, comets, interstellar dust and gas, stars of most spectral types, galaxies and galactic halos, Seyfert galaxies, and quasars (see ultraviolet astronomy). IUE became the longest-lived astronomical satellite ever, and finally ceased operating in 1996.