ORFEUS
ORFEUS was an ultraviolet telescope with a mirror diameter of 1 m which was used in the missions of the space shuttle STS-51 from September 12 to 22, 1993 and STS-80 from November 19 to December 7, 1996. The name stands for O rbiting and R etrievable F ar and E xtreme U ltraviolet S pectrometer, or O rbitales and R ückführbares F reap and E xtrem- U ltraviolett- S pektrometer. ORFEUS was a joint project by NASA and DARA .
ORFEUS was mounted on the free-flying platform ASTRO-SPAS , which was released by the shuttle and later captured again , so the two missions are also referred to as ORFEUS-SPAS 1 and 2. The large 1 m telescope could alternately supply two instruments with light, the Tübingen Ultraviolet Echelle Spectrometer TUES developed under the direction of the Eberhard Karls University of Tübingen for the wavelength range 90–140 nm (spectral resolution R ~ 10000), or the one from the University of California, Berkeley developed the Berkeley Extreme and Far-UV Spectrometer BEFS for 39-120 nm (R ~ 3000). The third instrument, the Interstellar Medium Absorption Profile Spectrograph IMAPS, developed by Princeton University recorded high-resolution (R ~ 75000) spectra in the 95–115 nm range with a separate, smaller telescope in order to examine the interstellar medium from absorption lines in the spectra of hot stars .
During the flights, spectra of 62 objects with TUES, 175 objects with BEFS and 39 objects with IMAPS could be obtained. ORFEUS mainly examined hot stars and was about a hundred times more sensitive than Copernicus (OAO-3) , or provided with ten times better spectral resolution than the Hopkins Ultraviolet Telescope . Other targets were interstellar matter , certain binary stars , planetary nebulae , white dwarfs and active galactic nuclei .
ORFEUS is now a central object in the astrophysical collection of the MUT University of Tübingen museum .