NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Using a theodolite as a (solar) sextant
From: Paul Hirose
Date: 2008 Feb 14, 11:04 -0800
From: Paul Hirose
Date: 2008 Feb 14, 11:04 -0800
Isonomia wrote: > I did however, try a few lower stars, and for the record, it is quite > possible to view the cross hairs, by shining a small torch into the > front of the telescope. WIth the x30 optics, I got a very clear image > of the star with a orange glow background (my torch had a red LED > setting which I preferred to white) Another way is to wrap a hand around the muzzle of the flashlight, with your index finger protuding into the beam. Then stick this illuminated finger into the telescope's field of view. I've found this method easier to manage than shining the beam directly into the scope. You may enjoy this solar observing FAQ: http://jeff.medkeff.com/astro/faq/ Surveying textbooks explain how to determine latitude, longitude, and true north with a theodolite. Books before the GPS era tend to be more thorough on astro techniques. You can probably find a good one at a library, or online (e.g., Google Books) in scanned form. In addition, these books have instructions on adjusting an instrument. > Is there any way to view the image at 90? .... Don't tell me a false > horizon! What you are calling a "false horizon" is something navigators call an "artificial horizon". There are right angle eyepieces for theodolites, but they're scarce. One exception is the theodolites now being sold by a Chinese manufacturer. These come with a solar filter and right angle eyepiece. But I suspect a new instrument would be too expensive for your purposes. http://www.southsurveying.net/SouthET.html -- I block messages that contain attachments or HTML. --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to NavList@fer3.com To , send email to NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---