NavList:

Geoff Hitchcox, for this Sun-Moon fix you found:
  82°38'N, 86°59'W.
And you spotted an error in Lars Bergman's original post (since repaired) which gave:
  82°38'N, 87°57'W.

Good catch, and I don't want to take away from that!

But for some of the celestial navigation newcomers here, I think it's worth pointing out that this difference is much smaller than it looks. If we do polar navigation problems and look at differences in longitude purely, you may see errors like this of one degree or even two degrees, or if you're really close to the pole, possibly five degrees of longitude. That sounds big!

As we all know, lines of longitude converge towards the poles, and as they do, a difference in longitude becomes smaller and smaller in terms of miles on the ground. One degree of longitude at the equator is basically the same as one degree of latitude --60 nautical miles, nearly. Climb towards the pole, and by the time we reach 60° latitude, one degree of longitude has shrunk by a factor of two --it's only 30 nautical miles. Continue to 82.63° of longitude, like in this scenario, and it's reduced in size by nearly a factor of eight --making one degree of longitude up there only 7.7 nautical miles. The reduction factor at any latitude is just cos(latitude). 

Lars repaired his calculation by noting that he had made a minor mistake on interpolating the Moon's declination, which was off by 6.3'. It might have seemed strange that this could throw the longitude off by a whole degree! But on the ground, the position was only off by 7.4 nautical miles. That's more in line with the original error.

Frank Reed