
NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: first sextant sights
From: Frank Reed CT
Date: 2006 May 10, 00:58 -0500
"Out of 9 sights the largest error I had (using Frank's online utility) was
0.3'. I had 3 sights that reduced and showed 0' error (honest!)."
Sounds good to me. I find that I can get distances with a standard deviation
of about 0.25' of arc repeatably as long as I'm using a good, well-adjusted
sextant. However, there is real variability even among expensive metal
sextants, and it's not at all unusual to see considerably larger errors.
I shot a bunch of lunars myself this week and discovered once again an
interesting problem for me personally --I'm terrible at lunars with stars! I get
good results (within the error limits I stated above) when I use the Sun,
Jupiter, Saturn, and Mars when it's close. But my lunars with stars are
consistently worse. This week I noticed that my near limb lunars were all short by
about 0.8 minutes of arc while my far limb lunars were all long by about the
same amount. So apparently, when I shoot lunars with stars, I have a tendency to
see contact when the star is actually some distance away from the limb. It
will be interesting to see if I can "un-learn" this...
-FER
42.0N 87.7W, or 41.4N 72.1W.
www.HistoricalAtlas.com/lunars
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From: Frank Reed CT
Date: 2006 May 10, 00:58 -0500
"Out of 9 sights the largest error I had (using Frank's online utility) was
0.3'. I had 3 sights that reduced and showed 0' error (honest!)."
Sounds good to me. I find that I can get distances with a standard deviation
of about 0.25' of arc repeatably as long as I'm using a good, well-adjusted
sextant. However, there is real variability even among expensive metal
sextants, and it's not at all unusual to see considerably larger errors.
I shot a bunch of lunars myself this week and discovered once again an
interesting problem for me personally --I'm terrible at lunars with stars! I get
good results (within the error limits I stated above) when I use the Sun,
Jupiter, Saturn, and Mars when it's close. But my lunars with stars are
consistently worse. This week I noticed that my near limb lunars were all short by
about 0.8 minutes of arc while my far limb lunars were all long by about the
same amount. So apparently, when I shoot lunars with stars, I have a tendency to
see contact when the star is actually some distance away from the limb. It
will be interesting to see if I can "un-learn" this...
-FER
42.0N 87.7W, or 41.4N 72.1W.
www.HistoricalAtlas.com/lunars
--~--~---------~--~----~------------~-------~--~----~
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To unsubscribe, send email to NavList-unsubscribe@fer3.com
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