@unpublished{DuranGuestenRisacheretal.2020,
  author  = {Carlos A. Dur{\´a}n and Rolf G{\"u}sten and Christophe Risacher and Andrej G{\"o}rlitz and Bernd Klein and Nicolas Reyes and Oliver Ricken and Hans-Joachim Wunsch and Urs U. Graf and Karl Jacobs and Cornelia E. Honingh and J{\"u}rgen Stutzki and Gert de Lange and Yan Delorme and Jean-Michel Krieg and Dariusz C. Lis},
  title   = {4GREAT -- a four-color receiver for high-resolution airborne terahertz spectroscopy},
  institution = {Fachbereich Ingenieurwissenschaften und Kommunikation},
  pages     = {11},
  year    = {2020},
  abstract  = {4GREAT is an extension of the German Receiver for Astronomy at Terahertz frequencies (GREAT) operated aboard the Stratospheric Observatory for Infrared Astronomy (SOFIA). The spectrometer comprises four different detector bands and their associated subsystems for simultaneous and fully independent science operation. All detector beams are co-aligned on the sky. The frequency bands of 4GREAT cover 491-635, 890-1090, 1240-1525 and 2490-2590 GHz, respectively. This paper presents the design and characterization of the instrument, and its in-flight performance. 4GREAT saw first light in June 2018, and has been offered to the interested SOFIA communities starting with observing cycle 6.},
  language  = {en}
}