The Confusion Limits to the Sensitivity of Submillimeter Telescopes

Outside of the Galactic plane there are two major sources of confusion that limit the sensitivity of con tinuum observations at submillimeter wavelengths the spatial structure of the thermal emission from dust in the Milky Way and the crowding of extra galactic sources at faint levels We present estimates of the noise expected from these two types of con fusion as a function of wavelength and beam size on the sky and compare them to detector and pho ton noise estimates for proposed space borne tele scopes Confusion noise cannot be reduced by longer integration times or more sensitive detectors and can limit the performance of cryogenic telescopes in the one meter class to a photometric uncertainty between and mJy at m