NavList:

   

Reply

Bill you asked:
"Does your online lunars  calculator take phase into account for Venus or
other bodies?"

No.  There is no "obvious" way to do this that is unambiguously correct.
Also, if  phase is large enough to worry about, you can *see* it (once you know
what  you're looking for at least). As Venus gets closer to us, take a look at
it with  your sextant's telescope. If it's approaching one arc-minute in
diameter, then  through a 7x telescope, it will have an apparent diameter of more
han five  arc-minutes. That's plenty big enough to resolve with the human eye.
You'll  actually see a tiny crescent through the sextant. So you should still
be able to  estimate the location of the planet's center and park that spot
right on the  lunar limb when you're shooting lunars. And by the way, when in
doubt about the  size and phase, pull out a little telescope and take a  look!

Historically, no correction was made for phase. I think that's  still
appropriate, but John Letcher in his book "Self-Contained Celestial  Navigation with
H.O. 208", which includes some good info on shooting modern  lunars,
recommends avoiding Venus and also Mars completely. This is partly  because of the
phase issue, but more importantly, his simplified method for  clearing lunar
distance sights could not handle planetary parallax. This is a  unique feature of
his method, so I don't think it's really necessary to follow  that advice.

-FER
42.0N 87.7W, or 41.4N  72.1W.
www.HistoricalAtlas.com/lunars

   

Reply