An analysis of the errors in John Flamsteed's Mural Arc observations

Abstract

An accurate analysis of the random and systematic (bias) errors of Flamsteed's Mural Arc and the observations made using it could not be made until the end of the twentieth century. It is only in the last decades that the quantitative representation of the Astronomical Reference Frame and the Astronomical Constants have reached the required precision. In this study, it is possible to predict the true time of a meridian transit of a star (subject to an uncertainty in ΔT) and the true observed zenith distances (subject to the uncertainty in the refraction). These can be compared to Flamsteed's clock times of wire crossings and readings of the Mural Arc. Statistical analyses have been applied to a sufficient number of observations to determine standard deviations. Bias errors can be modeled by least squares fits to Flamsteed's determinations.