Large format heterodyne arrays for observing far-infrared lines with SOFIA

In the wavelength regime between 60 and 300 microns there are a number of atomic and molecular emission lines that are key diagnostic probes of the interstellar medium. These include transitions of [CII], [NII], [OI], HD, H2D+, OH, CO, and H2O, some of which are among the brightest global and local far-infrared lines in the Galaxy. In Giant...