A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Position-Finding
From: Sean C
Date: 2015 Jul 8, 02:09 -0700
Tonight, I was cleaning and adjusting the errors out of my Astra IIIb when I decided to dust off my old Davis Mk. 15 as well. Curious to see what the index and side errors were, I took it outside to sight some stars. After allowing some time for temperature acclimatization, I found both errors were fairly large but easily adusted owing to the finger screws. I figured heck, while I'm out here, why not shoot a lunar just for fun. The only other body available (due to trees and light pollution) was Altair. Not an ideal body being 29 degrees from the ecliptic, but it was all I had. (However, the distance was changing at a rate of about 30' per hour, so...still usable.) At 07h55m53s UT, I measured the distance as 71°09.4' (far limb). Index error was 0, temperature: 77.9 °F, pressure: 29.75 in/Hg and height of eye 36 feet.
A quick check with Frank's online calculator yielded an error of just -0.3', or ~10' of longitude! Just goes to show that the Davis is quite capable of making good measurements as long as care is taken with the index error. Either that, or I just got lucky. :)