Several color filters have been developed for astronomic use in order to improve image quality in visual observations and astronomic photography. Various positive effects, which can be achieved in astronomic practice, have already been described by several authors, manufacturers and distributors [2, 4, 5, 9, 10, 12]. Monochromatic narrow-band filters are widely used by astronomers. These filters are constructed as interference filters; they select small ranges within the spectrum of the visible light corresponding with characteristic radiation emitted by celestial nebula or the sun and its protuberances. This way, scattered terrestrial radiation caused by “light pollution” and non visible infrared or ultraviolet spectral components are blocked. Fundamental improvements of image quality will result from these filters when refractors or reflector telescopes are fitted with them.
Boundary layer temperature measurements of a noctual urban boundary layer
