AN ACCURATE METHOD FOR COMPUTING ATMOSPHERIC REFRACTION

This paper describes a method for computing atmospheric refraction tha t is simple, highly accurate, and usable for wavelengths lambda lambda 3000-10,000 Angstrom. When compared with the Refraction Tables of the Pulkovo Observatory [Albalakin, V. R. 1985 (Leningrad, Nauka)], the c omputed and Pulkovo refractions are in extremely good agreement (simil ar to 10 mas or better) for zenith distances under 65 degrees, and at a zenith distance of 75 degrees, the agreement degrades to about simil ar to 150 mas. Moreover, this refraction is easy to compute, since onl y knowledge of the meteorological conditions at the observing site (e. g., ambient temperature, atmospheric pressure, and dew point or relati ve humidity), the apparent zenith distance of the object being observe d, and the location of the observing site relative to the Earth's geoi d are needed for its calculation. Because of its simplicity and high a ccuracy, the refraction presented in this paper is well suited for pro grams where huge amounts of data need to be processed quickly to star positions or for accurately setting automated telescopes. In addition, the refraction for a given telescope passband will differ in a way de pendent on the spectrum of the object being observed. This paper descr ibes how a mean refraction, weighting the selective refraction over th e passband, can be computed.