Wednesday, April 17, 2019

Celestial Navigation: Sight Reduction

work in progress...
I need some good days for photographing the sextant work.
9 May 2019, sunny but I had a conflict.
Norm

The Nautical Almanac is the one book required for sight reduction by hand.  The single volume Nautical Almanac is required when using other tables such as HO 211 or HO 249. Since the Almanac includes a set of tables and the useful forms required for sight reduction, no other books are required.

An excellent tutorial is available on YouTube here:
https://www.youtube.com/watch?v=gucO6eVtwVo&t=4s


Let's look at the NAO Concise Sight Reduction Form. In the 2019 Nautical Almanac, it is on page 319.


The instructions for using the pro-forma are found on pages 277 through 285.

The first two things a navigator needs are time and angle.  See my notes on that in an earlier post.  Once the time and altitude are captured, the calculation using the Almanac is not too complex.

Step 1.   please wait.


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