@article{RisacherGuestenStutzkietal.2018,
  author    = {C. Risacher and R. G{\"u}sten and J. Stutzki and H.-W. H{\"u}bers and R. Aladro and A. Bell and C. Buchbender and D. B{\"u}chel and T. Csengeri and C. Duran and U. U. Graf and R. D. Higgins and C. E. Honingh and K. Jacobs and M. Justen and B. Klein and M. Mertens and Y. Okada and A. Parikka and P. P{\"u}tz and N. Reyes and H. Richter and O. Ricken and D. Riquelme and N. Rothbart and N. Schneider and R. Simon and M. Wienold and H. Wiesemeyer and M. Ziebart and P. Fusco and S. Rosner and B. Wohler},
  title     = {The upGREAT Dual Frequency Heterodyne Arrays for SOFIA},
  series   = {Journal of Astronomical Instrumentation},
  volume    = {07},
  number    = {04},
  publisher = {World Scientific},
  issn      = {2251-1717},
  doi       = {10.1142/S2251171718400147},
  url       = {https://nbn-resolving.org/urn:nbn:de:hbz:1044-opus-43319},
  pages     = {1 -- 16},
  year      = {2018},
  abstract  = {We present the performance of the upGREAT heterodyne array receivers on the SOFIA telescope after several years of operations. This instrument is a multi-pixel high resolution (R≳107) spectrometer for the Stratospheric Observatory for Far-Infrared Astronomy (SOFIA). The receivers use 7-pixel subarrays configured in a hexagonal layout around a central pixel. The low frequency array receiver (LFA) has 2×7 pixels (dual polarization), and presently covers the 1.83–2.07THz frequency range, which allows to observe the [CII] and [OI] lines at 158μm and 145μm wavelengths. The high frequency array (HFA) covers the [OI] line at 63μm and is equipped with one polarization at the moment (7 pixels, which can be upgraded in the near future with a second polarization array). The 4.7THz array has successfully flown using two separate quantum-cascade laser local oscillators from two different groups. NASA completed the development, integration and testing of a dual-channel closed-cycle cryocooler system, with two independently operable He compressors, aboard SOFIA in early 2017 and since then, both arrays can be operated in parallel using a frequency separating dichroic mirror. This configuration is now the prime GREAT configuration and has been added to SOFIA’s instrument suite since observing cycle 6.},
  language  = {en}
}