NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Classic Trig Log Sight Reduction Revisited
From: Hanno Ix
Date: 2014 May 28, 08:27 -0700
From: Hanno Ix
Date: 2014 May 28, 08:27 -0700
Gentlemen
Re: Sight reduction by hand
I am happy Greg initialized the most recent discussion about
sight reduction by hand. It is a very noble art demanding
precision and concentration - like everything else in CelNav.
To make things easier I drew up the azimuth diagram you
seem to like.
May I, in this vein, direct your attention to another
May I, in this vein, direct your attention to another
simplification that occurred to me some time ago:
A method that circumvents virtually all concerns of others.
A method that circumvents virtually all concerns of others.
Some months ago I described it in my memo to navlist named
Sight Reduction by Hand you may like.
Sight Reduction by Hand you may like.
You may want to look it up.
It involves generally just 4 digit integers, mostly only addition and subtraction
and multiplication/division solely by 2 and 4. It handles positive
and negative angles with equal ease and is accurate at high latitudes.
and negative angles with equal ease and is accurate at high latitudes.
And it employs a trig table - not log trig table - of just 2 pages.
I am surprised it has not found takers so far.
I am surprised it has not found takers so far.
Included in the memo are the table, a worksheet, a narrative and an example.
Give it a try.
Hanno
PS: there is an errata in the narrative - easy to spot :(
On Tue, May 27, 2014 at 9:21 PM, Greg Rudzinski <NoReply_Rudzinski@fer3.com> wrote:
Thanks Frank. The pictured index card shows an example of a classic trig log sight reduction for a Sun observation made earlier today with a bubble octant.
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