I just spent far too long trying to get automatic calculation of magnetic declination to work, and I'm posting my findings so that others don't make the same mistake, and so that therion (an already great piece of software) can be improved accordingly. I've found that... Specifying the fixed coordinate before the coordinate system causes therion to silently fail to apply declination. In other words, this is wrong: date 2007.06.31 fix A0 626333 4320333 2620 cs UTM17 Specifying the coordinate system before the fixed coordinate causes therion to properly calculate magnetic declination. This is correct: date 2007.06.31 cs UTM17 fix A0 626333 4320333 2620 Therion 0.5.1 does this completely silently, with no notification that declination has been applied at all. Therion 0.5.0 prints the following (rather confusing) message in therion.log: output coordinate system: EPSG:32617 meridian convergence (deg): -0.9190 geomag declinations (deg): 2007.1.1 -8.9944 2008.1.1 -9.0224 My recommendations are that therion should: - Ignore the order of 'cs' and 'fix', apply declination as long as both are included - Explicitly state that declination has or has not been applied, regardless of configuration, so users are aware of this - Emit a warning if partially or incorrectly configured for magnetic declination calculation Thanks very much! Dave Riggs Morgantown, WV -- David A. Riggs <david.a.riggs@gmail.com>