STO is a dedicated galactic mapping instrument for
the astrophysically important spectral lines [N II] at 1461 GHz
and [C II] at 1900 GHz and an ideal complement to the larger,
individual target focused Herschel and SOFIA instruments. The
2 4-pixel heterodyne receiver of STO will utilize a 1.4 THz
band focal plane array from the Jet Propulsion Laboratory and
one at 1.9 THz from the U. Köln.