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post #9 of Old 04-05-2012
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Re: practicing with sextant on land

I'm new to the forum. Thanks everyone, especially AdamLein for the explanations. I use GPS for work and travel but am interested in navigation using basic skills. I just bought a second hand Davis 15 sextant and am learning how to use it and do the calculations. I'm landlocked in Burnaby BC so have been using a pan of water (just water, no oil, pan placed in a dark place in the backyard). It worked great last night with the full moon. However my latitude came out somewhere in the lower USA!

Am I correct that for the sextant reading (assuming I've zeroed out all index error in the sextant) that I superimpose the 2 images of the moon (direct and reflected) and divide the angle by two as my starting figure? My Ha came out at 31.5 deg however. I made sure I had the time relative to GMT and even cheated and entered GPS coordinates for the Dr.

To get used to the sextant first I'm using the Celestial app for Android for the calculations. It also gives almanac figures for when I move to doing the calculations myself.

So my question is whether I do the reflected moon shots the same way as described for sun shots using a reflecting surface and taking half the angle off the sextant as my starting number for the sight reduction?

This is great, thanks everyone,

Last edited by tony9; 04-05-2012 at 12:53 PM.
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