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Precision in determination of astronomical refraction from aerological data
Author(s) -
KurzyńSka K.
Publication year - 1987
Publication title -
astronomische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.394
H-Index - 63
eISSN - 1521-3994
pISSN - 0004-6337
DOI - 10.1002/asna.2113080508
Subject(s) - zenith , refraction , refractive index , depth sounding , physics , optics , atmospheric refraction , geology , oceanography
Various errors in determination of the local pure astronomical refraction are evaluated versus the apparent zenith distance z 0 . Numerical integration with the step imposed by heights of an aerological sounding brings the error smaller than 0″01 until z 0 = 70°. For larger zenith distances integration with a more dense step is possible after fitting the data to a five‐parameter functional dependence of the refractive index on height. The fitting is simultaneously a good equalization of aerological data reducing considerably their experimental error as well as short‐term local fluctuations of the atmosphere. After equalization, the error in the refraction originating from the error in the aerological data is found to approach 0″01 at z 0 = 72°, 0″1 at z 0 = 82°, 1″ at z 0 = 87°, and 10″ at the horizon. This has to be taken into account when considering systematic deviations of the local pure refraction from that determined in a standard way. The purely stochastic error in the refraction originating in the error of the refractive index at the observation site is discussed within the context of local fluctuations of the atmosphere. It is evaluated that until z 0 = 85° the precision in determining the astronomical refraction in a single observation is limited by refraction anomalies (image motion) and only above 85° the error in aerological data becomes more important.