NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: GHA = GAST - RA Astronomical Almanac vs Nautical Almanac
From: Stan K
Date: 2014 Mar 22, 20:36 -0400
From: Stan K
Date: 2014 Mar 22, 20:36 -0400
Mike (and members),
Ignore my message of seconds ago. I typed before I read .
Stan
Ignore my message of seconds ago. I typed before I read .
Stan
-----Original Message-----
From: Mike Mayer <mwmayer@tds.net>
To: slk1000 <slk1000@aol.com>
Sent: Sat, Mar 22, 2014 3:32 pm
Subject: [NavList] GHA = GAST - RA Astronomical Almanac vs Nautical Almanac
From: Mike Mayer <mwmayer@tds.net>
To: slk1000 <slk1000@aol.com>
Sent: Sat, Mar 22, 2014 3:32 pm
Subject: [NavList] GHA = GAST - RA Astronomical Almanac vs Nautical Almanac
Hi,
Anyone know what I'm missing? In comparing the Sun's GAST - RA from the Astronomical Almanac to the GHA in the Nautical Almanac there are cases that seem to be too far off. For example, for January 1, 2014 at 0 UT I get:
GAST = 6h42m17.0580s = 6.704738333h (Page B13)
RA = 18h45m35.31s = 18.759808333h (Page C6)
RA = 18h45m35.31s = 18.759808333h (Page C6)
GAST - RA = -12.055070000 = 11.944930000h = 179.17395° = 179°10'26.22"
= 179°10.437'
= 179°10.437'
The Nautical Almanac has 179°10.2'
The difference is 0.237', which is outside the accuracy the Nautical Almanac specifies for the GHA Sun data in the paragraph numbered 24 on page 261 of the commercial version of the Nautical Almanac 2014.
What am I missing ?
Thanks!
----------------------------------------------------------------
NavList message boards and member settings: www.fer3.com/NavList
Members may optionally receive posts by email.
To cancel email delivery, send a message to NoMail[at]fer3.com
----------------------------------------------------------------
----------------------------------------------------------------
NavList message boards and member settings: www.fer3.com/NavList
Members may optionally receive posts by email.
To cancel email delivery, send a message to NoMail[at]fer3.com
----------------------------------------------------------------