NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Greg Rudzinski
Date: 2012 Feb 17, 05:31 -0800
Gary,
It looks to me like Sidereal time is replaced by the hour angle of Aries and right ascension is replaced by the sidereal hour angle in the current Nautical Almanac. This allows for the convenience of adding rather than subtraction. Any other advantages to the modern NA arrangement ? Is there an advantage to the old way ?
Greg Rudzinski
[NavList] Re: Mean Solar into Sidereal Time
From: Gary LaPook
Date: 16 Feb 2012 22:10
The reason for those tables in H.O. 208 (also found in Bowditch at least through the 1938 edition) is that in the olden days the positions of celestial bodies were listed by Right Ascension. So to find your local angle you first calculated your local sidereal time and compared it with the RA of the body, the difference is the LHA. See excerpts from NA 1937 located on my website here:
https://sites.google.com/site/fredienoonan/resources/nautical-almanac-1937
Also see attached pages from Air Navigation, Weems, 1938.
gl
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