Systematic Errors in High Latitude Astronavigation

In polar astronavigation, refraction corrections have always been an important concern. Whatever the magnitude of the error in a refraction value, the error has been expected to remain essentially constant during a given series of observations (a series being defined as consecutive observations on a single celestial body taken in a relatively short time span). Based on this expectation, Hussain suggested assuming that each series of observations contains a constant (systematic) error and that this error could be determined as part of a least squares solution for the latitude and longitude. The proposed modification would solve for several unknowns (latitude, longitude, and corrections to the refraction values in a series). To evaluate this idea, the writer develops a procedure for predicting the accuracy of the various viewing configurations used. For this investigation, this procedure was modified to also solve for the accuracy of the systematic corrections. Tables are presented showing the results of both methods. The Hussain idea has limitations in terms of obtainable accuracies; the modified version is shown to be usable for the reduction and analysis of high latitude astronavigation observations and fixes.