NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Relative Importance of Accurate Timing of Sight for Lunars versus Altitude Sights
From: Fred Hebard
Date: 2003 Jun 9, 22:48 -0400
From: Fred Hebard
Date: 2003 Jun 9, 22:48 -0400
It has taken me a long time to where I can consistently get my altitude sights to under 0.5' of arc from a known position on dry land, often, now, under 0.2' of arc. A critical component of that has been judging the exact moment of contact and hitting the stop watch accurately at that moment. After setting the angle, I generally wait for the object to converge with the horizon, or itself in the artificial horizon, and try to hit the stop watch when contact occurs. However, I always had a fair amount of luck with lunars, even before improving my timing technique for altitude sights. That was back when I would look down at my watch after perfecting the contact and record the time. I still prefer this second method for lunars and believe it is the best for that observation. That is because 12 seconds of time elapse, more or less, between each shift of 0.1' of arc in a lunar. It doesn't make much difference whether you're 2-4 seconds out. It's much more important to get the angle measured to the utmost precision possible than to time the sight accurately. You need to concentrate much more on proper manipulation of the micrometer than on the time, like when checking index error by determining the semi-diameter of the sun. Any comments?