A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Frank Reed
Date: 2015 Dec 9, 08:54 -0800
Antoine, you wrote:
"Frank's On-Line Lunar Calculator has been improved into tackling "zero distance Lunars" i.e. actual Occultations very well. This is a remarkable achievement since as we know, the accuracies of [all known] classical Lunar Methods definitely degrade for short distances between Body and Moon Limb(s), hence the constant caveats about their usable minimum distances (generally not to be inferior to a very minimum of 5° to 7°) between Moon Limb and other body limb."
Just to clarify, nothing's been "improved" or significantly changed in my web app in years. It has always handled occultations in the same way. It works with occultations, to the same extent that it always has. The difference is that I offer no warranty on occultations, in contrast with lunars! Use at your own risk with occultations! Not for navigation! :) The web app is built for analyzing standard lunars, and I have done no planning or testing to guarantee that it will work with occultations. Of course occultations are "zero distance lunars" so at some level it has to work. But I can imagine that there are issues. If I get some time, I will investigate more. It's an interesting problem but not a high priority, as I see it, since occultations were rarely, if ever, used for anything resembling "practical" navigation. They were used for some astronomical position-finding, but in a relatively limited window. Historically, occultations were more important for determining the Moon's position rather than the observer's position.