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Re: Sight Reduction Formula Question
From: Fred Hebard
Date: 2005 Jan 7, 17:02 -0500

```Dear Fried Squash,

I'd salute you by name, but can't find it in your posts, which I can
understand as a desire to avoid spam, etc.

The one thing to watch out for in Turner's book is that he mentions
that one can determine interstellar angles when the stars are at equal
altitudes, without accounting for refraction.  This is simply wrong.
One might want to calculate those angles to measure sextant accuracy.
Other than that, I found the book very useful.  This error also is
present in Bruce Bauer's book, The Sextant Handbook, and, I believe, in
modern editions of Bowditch.

BTW, Welcome to the list!

Fred

On Jan 7, 2005, at 11:19 AM, Fried Squash wrote:

> Thanks Fred, you are absolutely correct, Turner does
> indeed explain that the short one can yield 180 deg
> ambiguity.  I should have kept reading.
>
> --- Fred Hebard  wrote:
>> I believe Turner gives the reason for the longer
>> formula and also shows
>> the shorter one, saying the shorter one can be
>> inaccurate in some cases.
>> Fred
>>
>> On Jan 7, 2005, at 10:24 AM, Fried Squash wrote:
>>> In _Celestial for the Cruising Navigator_ by Merle
>>> Turner, the navigational triangle azimuth formula
>> is
>>> given as:
>>>
>>> cos Z = (sin d - (sin L * sin H ))/(cos L * cos H)
>>>
>>> but Dutton's Navigation and Piloting gives the
>> much
>>> simpler:
>>>
>>> sin Z = ( cos d * sin t ) / cos H
>>>
>>> They both seem to work.  But there must be some
>> reason
>>>  that the longer one is better, right? Works in
>> more
>
>
>
>
> __________________________________
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```
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