NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: ÉPHÉMÉRIDES NAUTIQUES- 2012 -----Complete PDF Online Free
From: Stan K
Date: 2012 Feb 11, 12:16 -0500
From: Stan K
Date: 2012 Feb 11, 12:16 -0500
Dave,
For me the problem was not so much which almanac was the most accurate. I was simply looking for a way to save the students some money. For instance, with the way that the Power Squadrons Junior Navigation course has been revised, all the required sights can be done in one day, and I mean "day", since only sun sights are required. There seemed to be no reason for everyone in a class to purchase a current almanac. It would be enough for one almanac to be purchased for the entire class, or, as far as the daily page goes, have someone with a current almanac make a copy of that one page. The issue then becomes the Increments and Corrections. We tried NavSoft, but found a discrepancy with the first reduction we tried. I ended up loaning old almanacs to the students. Eventually I added an Increments and Corrections tool to my computer program, and, with a few tweaks, I believe I have it so all 21900 values match the printed US almanac. My GHAs and Decs are still only of medium precision, which is a good thing since one of my mandates from the Power Squadrons was that the program would help the students find their errors, not do the work for the student.
Stan
For me the problem was not so much which almanac was the most accurate. I was simply looking for a way to save the students some money. For instance, with the way that the Power Squadrons Junior Navigation course has been revised, all the required sights can be done in one day, and I mean "day", since only sun sights are required. There seemed to be no reason for everyone in a class to purchase a current almanac. It would be enough for one almanac to be purchased for the entire class, or, as far as the daily page goes, have someone with a current almanac make a copy of that one page. The issue then becomes the Increments and Corrections. We tried NavSoft, but found a discrepancy with the first reduction we tried. I ended up loaning old almanacs to the students. Eventually I added an Increments and Corrections tool to my computer program, and, with a few tweaks, I believe I have it so all 21900 values match the printed US almanac. My GHAs and Decs are still only of medium precision, which is a good thing since one of my mandates from the Power Squadrons was that the program would help the students find their errors, not do the work for the student.
Stan
-----Original Message-----
From: Dave Walden <waldendand@yahoo.com>
To: NavList <NavList@fer3.com>
Sent: Sat, Feb 11, 2012 8:06 am
Subject: [NavList] Re: ÉPHÉMÉRIDES NAUTIQUES- 2012 -----Complete PDF Online Free
From: Dave Walden <waldendand@yahoo.com>
To: NavList <NavList@fer3.com>
Sent: Sat, Feb 11, 2012 8:06 am
Subject: [NavList] Re: ÉPHÉMÉRIDES NAUTIQUES- 2012 -----Complete PDF Online Free
The Skyhorse appears to be a "commercial" version of the US Naut Alm. (like that available from Celestaire).
I don't believe that many others make the "adjustments" that the US Naut Alm does to minimize the maximimum error when using their interpolation tables. (as described in the Naut Alm) ((I played with this some time ago, and eventually was able to get exact agreement with the Naut Alm starting with JPL))
It is my opinion, I believe shared by others, that the French are as good as or better than JPL at ephemeris generation based on recent publications.
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