This grant supports the development and testing of a novel optical instrument for determining night sky clarity. A modulated Ronchi grating will provide a modulated output that is sensitive to sky clarity when a wide field of stars is observed. This output can be used to determine whether the sky is sufficiently clear to conduct observations of faint night sky emission lines. It is expected that this instrument will be especially useful for operations from remote sites, or from sites operated by personnel inexperienced in judging whether conditions are suitable for observations. Reproduction of the developed instrument is expected to be inexpensive, and its widespread application is foreseen.
