NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: azimuth bearing on celestial bodies
From: Peter Fogg
Date: 2005 Aug 21, 10:24 +1000
From: Peter Fogg
Date: 2005 Aug 21, 10:24 +1000
I have a friend who has a sextant scope with built-in compass. Way to go. Using a 'hockey-puck' type of hand bearing compass (Plastimo) works well for me; especially for bodies at moderate elevation. No, it can't be pointed far from a horizontal plane. I think taking a compass bearing as part of the sight taking process is a good idea. The advantages work all ways: to help identify a body if necessary, to have a reasonable idea of azimuth, and, not least; to ascertain the local compass error (deviation) in that direction, which is what is left of that compass bearing once the magnetic variation is accounted for from the calculated azimuth. Todd you wrote: > > What is the best way to find an approximate bearing on a celestial body or > conversely, to find a celestial body using a bearing? I've been doing it > lately by simply facing forward in the direction of the sun/planet/moon > after shooting a sextant sight and trying to be accurate using my trusty > Silva hiking compass with sighting mirror. This has worked well in the > past > for getting rough estimates which I use as a check on my calculated > azimuth. > But I just recently purchased a Starfinder 2102-D and find that I might > need a more accurate way to find a bearing in help locating the desired > star. I'm thinking I'll just stand facing the general direction with the > sextant set for the proper altitude of the body (according to 2102-D) and > start scanning. But then this just seems somewhat inaccurate and dicey to > me. Do I need a handbearing compass? It seems that any advantage of a > handbearing compass would be obviated by the fact that it must be tilted > up > at an angle to get a truly accurate reading, and tilting compasses (in my > experience) causes the card to become dampened, thus no actual bearing can > be found. How is this done by other navigators, short of purchasing an > astrocompass? > Todd Shanklin > Long Beach, CA >