NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Exercise Lunar Distance with Mercury
From: Antoine Cou�tte
Date: 2009 Sep 23, 03:07 -0700
From: Antoine Cou�tte
Date: 2009 Sep 23, 03:07 -0700
Frank, Thank you very much for your quite interesting feedback and comments. May I ask one question here regarding Lunars with "significantly phase angled planets" (i.e. Venus and Mercury)? Since phase angle can be fully accounted for in Body Coordinates Computation, what would you think of shooting such "Inferior Planets Lunars" through observing this Planet through carefully selecting one of your "opaque" glasses on your sextant (i.e. brightness reducing glass, sorry I do not remember the name of such glasses in English, and I think that you would select the one with the least efficiency if you have one installed), so that it would reduce the ?Planet to a "light pinpoint" ? This method might also take good care of "getting rid" of additionnal observation inaccuracies due to the Planet semi-diameter because if you swing-kiss the Planet center of light instead of some Planet limb, you then can just ignore Planet Semi-diameter value (i.e. make it equal to Zero) in your computational data processing. The reason I am asking this is simply because you have indicated more than once that you do not seem as confident with Planet Lunars than with Stars Lunars. The "slightly opaque glass" trick would aim to reducing the planet into a light pinpoint mostly similar to a star light pinpoint. The only remaing difference between Star and Planet Lunars would then essentially be correctly handling horizontal parallax correction for the Planet, an effect which on some occasions can reach 0.4' for Venus. Thanking you for your kind Attention, I am remaining most Sincerely Yours, and thank you again for the Navlist site which I am truly enjoying more and more Antoine Antoine M. "Kermit" Couette PS : Did you have the opportunity to cross-check the results I published and commented in thread "NavList 9816" (also found in "Navlist 9868")? In NavList 9816 I did reduce Lunars in an "UNCONVENTIONAL WAY". Instead of reducing them to the center of the Earth (to further compare them to published/computed geocentric Lunar Center/Body Center distances) I choose here to directly compare Sextant readings (corrected only for Instrument error) with computed sextant readings derived from an assumed knowledge of the environment, whether UT, Observer's position, Lunar Sextant Distance corrected for instrument error, and Lunar/Body sextant heights. --~--~---------~--~----~------------~-------~--~----~ NavList message boards: www.fer3.com/arc Or post by email to: NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---