# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Re: Classic Trig Log Sight Reduction Revisited
From: Greg Rudzinski
Date: 2014 May 28, 14:17 -0700

Hanno,

I gave your method a look and tried reducing the sun observation I posted yesterday. No luck. Filled one entire side of a legal pad only to get hopelessly bogged down in negative numbers :(

My personal requirement for a useful reduction method is being able to perform the needed task on one side of a standard index card without the need for a form or other formulae aid. I dislike the reduction tables that are included with the Nautical Almanac because it doesn't meet this requirement. There might be hope for your method if you can find a way to eliminate all the negative numbers and rules.

Greg Rudzinski

Re: Classic Trig Log Sight Reduction Revisited
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
simplification that occurred to me some time ago:
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.

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 it employs a trig table - not log trig table - of just 2 pages.
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 :(

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