The 'submillimeter' region of the electromagnetic spectrum is at the
border between the far infrared and the short-wavelength radio regions. As
such, it borrows technologies from both regimes: bolometers from the
infrared, heterodyne receivers from the radio.
Wavelength: 300 microns to 1 millimeter
Frequency: 300 Gigahertz to 1 Terahertz
the frequencies transmitted by the atmosphere over Mauna Kea. The
atmosphere is the greatest problem faced by submillimeter astronomers,
which, combined with the lack of high-performance instrumentation, explains
why the submillimeter region of the spectrum is currently the least well
studied. Astronomy can only be done in the submillimeter at sites with
extremely dry atmospheres, such as the tops of mountains and the antarctic.
Where does submillimeter emission come from in the universe?