 For sub-millimeter wavelengths (from around 200 µm to 1 mm wavelength, also known as the far-infrared or terahertz), bolometers are among the most sensitive available detectors, and are therefore used for astronomy at these wavelengths.To achieve the best sensitivity, they must be cooled to a fraction of a degree above absolute zero (typically from 50 mK to 300 mK).Notable examples of bolometers employed in submillimeter astronomy include the Herschel Space Observatory, the James Clerk Maxwell Telescope, and the Stratospheric Observatory for Infrared Astronomy (SOFIA).