A system for detecting atmospheric trace gas emissions from a specific target location by way of an observation platform, the system comprising: - a platform; - an image gathering device located at said platform, said platform being configured for overflying said specific target location, said image gathering device being configured for gathering multiple images of said specific target location as said platform overflies said specific target location; - a wide-angle, high finesse Fabry-Perot interferometer, said interferometer being located at said platform and being configured for receiving multiple light beams having a range of incidence angles such that light gathered from said specific target location passes through said interferometer before being received by said image gathering device; and - an order-sorting filter for filtering light from said specific target location prior to being received by said interferometer, said order-sorting filter being a bandpass filter transmitting a selected spectral range comprising at least two adjacent modes of the Fabry-Perot interferometer; characterized in that said Fabry-Perot interferometer comprises at least two mirrors, each of said at least two mirrors having the following characteristics: a surface roughness of less than 1 nm rms; a surface curvature of less than 2 nm; and a surface tilt of less than 2 nm, and said Fabry-Perot interferometer is configured such that spectral information at all wavelengths of the selected spectral range is acquired by the Fabry-Perot interferometer, so that spectral selection is achieved as a result of the angular wavelength shift and the order-sorting filter. - a platform; - an image gathering device located at said platform, said platform being configured for overflying said specific target location, said image gathering device being configured for gathering multiple images of said specific target location as said platform overflies said specific target location; - a wide-angle, high finesse Fabry-Perot interferometer, said interferometer being located at said platform and being configured for receiving multiple light beams having a range of incidence angles such that light gathered from said specific target location passes through said interferometer before being received by said image gathering device; and - an order-sorting filter for filtering light from said specific target location prior to being received by said interferometer, said order-sorting filter being a bandpass filter transmitting a selected spectral range comprising at least two adjacent modes of the Fabry-Perot interferometer; said Fabry-Perot interferometer comprises at least two mirrors, each of said at least two mirrors having the following characteristics: a surface roughness of less than 1 nm rms; a surface curvature of less than 2 nm; and a surface tilt of less than 2 nm, and a surface roughness of less than 1 nm rms; a surface curvature of less than 2 nm; and a surface tilt of less than 2 nm, and said Fabry-Perot interferometer is configured such that spectral information at all wavelengths of the selected spectral range is acquired by the Fabry-Perot interferometer, so that spectral selection is achieved as a result of the angular wavelength shift and the order-sorting filter. <EOS>