The function of the astronomical observatory is centered around the telescope. In addition to visual and photographic observations of astronomical bodies and phenomena, perhaps the most valuable use of the telescope is in connection with the spectroscopic study of starlight. The total light from a star is separated into its various wavelengths (see spectrum), and the intensity of each is measured. The temperature and chemical composition of stars can be obtained by this method, as well as information about stellar motion and magnetic fields. Using computers, astronomers can measure the spectra digitally recorded by spectrographs and photometers. Observatories specializing in solar astronomy usually have coronographs and spectroheliographs. Atmospheric limitations on telescopic observations include weather conditions, air turbulence, air glow, pollution, and any source of extraneous illumination. To minimize such conditions optical observatories are generally located at high altitudes in sparsely populated areas.
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