With support from this grant the PI will construct and deploy, at CEDAR and other field sites, a multiwavelength, computer controlled and pointed, stellar photometer to monitor the condition of the sky during airglow observations. Data will be obtained on atmospheric extinction at eight wavelengths including a water vapor absorption band. These data will permit the correction of airglow photometric data for absorption in the earth's troposphere. In addition, the background sky brightness will be monitored at each wavelength. Two wavelengths will be set at emission lines due to mercury and sodium which are emitted strongly by outside lights at night. Clouds illuminated by such lighting produces a strong source of sky pollution which reduces the quality of night sky observations. Results from this instrument will be invaluable to other observers who must operate their instrument in an unmanned automatic mode. With data corrected for extinction better agreement between observations and model predictions should result; likewise agreement between various observers' results should improve. Commercial devices will be used as far as possible to reduce development time. The resulting data set will be provided to campaign observers and will be deposited in the CEDAR data bank.
