* The index error is regarded as positive when the
angle displayed by the instrument is greater than the actual angle.
The internal almanac is based upon formulas given in Astronomical Algorithms by Jean Meeus, and is valid through approx. 2040 (cross-checked with Interactive Computer Ephemeris 0.51 by USNO). The almanac is usually accurate to 0.03'. Beyond 2010, the accuracy will probably slowly decrease but still remain better than 0.1' (comparable to the Nautical Almanac).
The program internally sets dip=0 if any form of an artificial horizon or a zenith distance is chosen. If an external artificial horizon (pan with liquid) is used, the sextant altitude is automatically divided by two after subtracting the index error.
This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the license or any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License (http://www.gnu.org/licenses/) for more details.
Henning Umland N 53° 20' 34'' E 9° 52' 00''
Check this web site for updated versions: https://www.celnav.de/index.htm