NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Longhand Calc's differ from Software Calc's
From: Stan K
Date: 2014 Nov 15, 20:30 -0500
From: Stan K
Date: 2014 Nov 15, 20:30 -0500
It might be because the computer solution uses the Law of Cosines from the DR position, where HO 229 works from an assumed position. Taking, for instance, the USNO Mars data provided, the computer solution would use 40ºN, 60ºW, where the HO 229 solution would use 40ºN, 59º49.1'W.
-----Original Message-----
From: Marty Lyons <NoReply_MartyLyons@fer3.com>
To: slk1000 <slk1000@aol.com>
Sent: Sat, Nov 15, 2014 8:17 pm
Subject: [NavList] Longhand Calc's differ from Software Calc's
From: Marty Lyons <NoReply_MartyLyons@fer3.com>
To: slk1000 <slk1000@aol.com>
Sent: Sat, Nov 15, 2014 8:17 pm
Subject: [NavList] Longhand Calc's differ from Software Calc's
I took some sights and decided to reduce them longhand to stay in practice. I checked them with software. I find some significant differneces in the calculated altitudes. So I calculate some known correct sample problems longhand and compare to software, I find that the Hc's differ by 4-5 minutes. I am thinking this is pretty significant. I used the HO 229 longhand method and these websites for computer solutions.
The two websites pretty much agree. The differences appear to be in the Hc. Any thoughts on why HO 229 method leads to different results than computer solutions?
