Message text written by INTERNET:sundial@rrz.uni-koeln.de >Has anyone seen a correction for this flattening at the poles, or bowing around the equator? If so, please share.<
Jan Meeus (who else??!!) gives such an approximation in Astronomical Algirithms 2nd Ed. p85. He attributes the equation to H Andoyer: 'Annuaire du Bureau des Longitudes pour 1950 (Paris) page 145'. He then works an example involving the distance between Paris and Washington DC and quoting the possible error of about 50 metres. To put it into perspective the difference between the simple spherical assumption and this 'better' formula is about 15km. Patrick -
