Greetings, fellow dialists, I think I am most of the way to finding a solution to the problem of the divergence of great circle and rhumb line tracks in high latitudes. The NavPac Compact Data 2006-2010 book, produced by H. M. Nautical Almanac Office and published by TSO London (used to be The Stationery Office!) ISBN 0 11 887331 8, includes a disc which calculates great circle and rhumb line tracks using latitude and longitude. For both the rhumb line and great circle tracks it will calculate up to 99 waypoints by interval distance. These are only to the nearest 0.1 minute of latitude but should be enough to produce a curve and an indication of the departure of the great circle from the rhumb line.
To recap, in deciding the limits of an oil concession it should be made clear whether the linking lines are rhumbs or great circles. Much may depend on it, especially in high latitudes and more especially where national boundaries are concerned. A few tens of metres can be important, it seems. Now, back to sundials :-) . Frank, 55N 1W -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.476 / Virus Database: 269.10.11/909 - Release Date: 20/07/2007 16:39 --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial