NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Lunar Distances with Alex's SNO-T
From: Bill B
Date: 2006 Dec 02, 23:15 -0500
From: Bill B
Date: 2006 Dec 02, 23:15 -0500
Bill, you wrote: > "Point being, I seriously doubt the lasers you refer to meet the standards of > both monochromatic and collimated light. " Frank replied: > They're real lasers. They produce monochromatic, coherent light --no > cheating on the terminology. All lasers have some beam spread, and you can > counteract it, up to the diffraction limit, using a telescope... Ok. I'm buying into that. Been shopping. Found a straight-line laser for $5 after rebate at Ace. It's nice as the height in relation to the eyepiece doesn't matter much, and very easy to center on eye-side scope lens, but it does not produce the fine spike that a point source produces. Borrowed a friend's "Taiwan Tom" level laser complete with tripod and all the niceties, but the off/on knob is on the front so one cannot center the beam up with the scope. Finally, after realizing batteries for my aging Compaq pen/pointer gimme would be $12 and considering that a poor investment as the dot is more of an ellipse than a circle, I ferreted out a laser pointer/led light/pen at Wal Mart for the princely sum of $2.88! It works very well, with a fine vertical diffraction line. Refining rigs to mount it now, as well as producing a circle to mount on the eye end of the scope with a tiny hole to be sure I am shooting down the center of the scope. Centering the spot on the glass/mirror section of the horizon mirror is simple trial and error and can be done satisfactorily by eye. Using George's suggesting on how to determine the distance between the horizon mirror and index mirror working points, I set up the rigs for trial runs. The distance was only 40 ft, but the results were right on (probably beginner�s luck.) Last sun IE check was 0.788' on the arc. When matching the predetermined mirror distance, the sextant reading was just a hair below 0.8' on the arc. I'm looking forward to more stringent tests as greater distances. Thanks for the idea Frank. Alex You ready to grab some sextants, a pair of FRS radios and go play? Bill --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to NavList@fer3.com To , send email to NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---