Determination of the Instantaneous Values of Astronomical Atmospheric Refraction and Local Observational Modeling

A new application of astronomical atmospheric refraction in space geodesy is utilized. It is pointed out that in order to meet the high needs of this new application there must be an effective method by means of which the instantaneous value of atmospheric refraction can be directly determined. An atmospheric refraction model fitting in the geographical environment surrounding the observing station is established and then transformed into the neutral atmospheric refraction delay correction model. In this article the necessary conditions for the determination of the value of atmospheric refraction are briefly described. A method for the direct determination of the values of instantaneous atmospheric refraction in various directions and at various zenith distances by taking advantage of the observational principle of the low latitude meridian circle, explored by the Yunnan Observatory, is expounded and the atmospheric refraction observational models built on the basis of stellar spectral type classification in the 4 directions of east, south, west and north and by making use of the observed data are given.