NavList:

On the 17th of this month I shot a few Sun sights using my Davis AH and Astra IIIb. My results were less than stellar. The glass kept fogging up with condensation, making the reflected image quite blurry. I kept having to open the glass to let the condensation evaporate. I think my data clearly shows the effect it had on my sights.

After reading the Feb. 7th entry in David Burch's blog, "Molasses – The Eatable Artificial Horizon", I decided to give it a try. I used a small black saucer and a liberal amount of molasses. I set the saucer on the ground and I sat in a small folding chair. The reflected image in the molasses seemed to move in and out of focus very slightly, although the surface didn't seem perturbed by the breeze. I'm not sure why. However, my results were much better. I was able to shoot more sights without having to stop and adjust the AH. Less cloud cover helped, too. A small amount of pollen and other debris collected on the surface, but not so much as to make sights too difficult. I discarded the molasses when I was done because it had collected too much debris for my liking.

I did also try to consciously keep the Sun in the center of the field of view in the second round, which I neglected to do on the first round. This may account for some of the larger errors in the first set. I used a piece of cardboard with a peephole cut in it, a la Greg Rudzinski, to center my eye on the scope for both rounds.

Two spreadsheets are attached showing the data and a graph for both days. Following is additional data:

Apr 17
Temp.: 12.6 °C
Press.: 1034.4 mb
Index error: +0.5'
Watch error: 0

Apr 20
Temp.: 15.6 °C
Press.: 1024.3 mb
Index error: +0.5'
Watch error: 0

AP for both days: N 37° 03.3', W 076° 28.6'.

Cheers,
Sean C.
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