Facility back-ends on SOFIA.

The SOFIA observatory will be used by several groups for high resolution observations in the sub-mm or THz range. Many involved groups are developing multi-channel receivers, which need an appropriate number of back-ends with sufficient velocity coverage. For an array system with e.g. 16 mixers this implies that a frequency bandwidth of at least 16 GHz total is required for observations of galactic sources. Extra-galactic signals will need up to 16×4 GHz bandwidth. Since the requirements for the spectrometers are nearly identical for all heterodyne receivers, it is very desirable to have one set of back-ends available on SOFIA for all interested groups. Therefore the authors propose to build a complete set of high, medium, and low resolution spectrometers as facility back-ends on SOFIA in a joint program.