NavList:

Antoine, you wrote:
"Hence Observer's Latitude = N 18.6° "

I tried it just now by comparison with simulation in Stellarium, fiddling with the latitude and the time until all of the bright stars have the right relative orientations. I get 18.5° N for latitude. Heh. That's identical to yours at the limiting accuracy here. :) I can't say I'm surprised by this latitude. Although the caption says they're somewhere on the voyage from Tahiti to Hawaii, it makes much more sense that they did this "publicity photography" in home waters. And from accounts of previous voyages, they make a point of sailing to and from the south tip of the "Big Island" of Hawaii. That fits the observed latitude that we're seeing.

Another clue: look at that bright star right on the horizon below Crux. It looks like another first magnitude star comparable to Acrux. If it were a star, it would even have to be brighter since at such low altitude there would be significant extinction (reduction in brightness due to atmospheric absorption etc.). Is it an eruption of Eta Carinae?? No, wrong spot anyway... Maybe it's a supernova?! :) ...Or maybe it's a boat. That, too, fits with a position very close to Hawaii. It's busy out there.

Frank Reed
Clockwork Mapping / ReedNavigation.com
Conanicut Island USA