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

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Ex-Meridian Sight using Inmans
From: David C
Date: 2020 Jun 10, 03:01 -0700

Although it is just under two weeks to the winter solstice today was a perfect day for CN. The sky was blue, there was absolutely no wind and the temperature was a comfortable 14°C.  I took a few practice sights using the anti-spoof app and also took a noon sight. Rather than work the noon sight or calculate intercepts for the other sights I decided to  reduce an early PM sight by the ex-Meridian tables in Inmans (1932).

The meridian altitude was  51° 19' in an AH.

51°   19'

IC       -4

51 15

/2  25 37.5

SD/R    +14.1'

Ho = 25°   51.6 '   ----noon altitude

The PM sight was  UT 01 05 46     49°  30' 50"

Following the  procedure above ho = 24°  57.5'    --------PM sight

Now calculate apparant time

DR long = 175° 05.2'

UT 01 05 46

195°  08.1'

increment        1°   26.5'

GHA         196° 34.6'

LHA          371°  39.8'

- 360°

11°  39.8'

Inmans does nor have an arc to time table so I used Norie.......

Apparant time 0h 46m 40s  PM

Time of noon was 01 05 46    -  0h 46m 40s  = 00 19 06 which agrees with app on my phone.

Now calculate ex=meridian correction....

Table 1  9.888

Table2   8.009

Sum     17.897

From Table 3 correction = 54.2'

A second correction from table 4 is -0.2' so the correction is 54'

Finally compare the calculated correction with the actual

ho noonsight - ho pm sight  =  54.1'

This remarkable agreement suggests either luck or that my errors are systematic, not random, and that they cancel out on subtraction of the two altitudes!

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