NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Online sight reduction program
From: Lu Abel
Date: 2013 Dec 27, 10:32 -0800
From: Lu Abel
Date: 2013 Dec 27, 10:32 -0800
Geoffrey:
At the USNO site (for which several have sent the URL), you enter your latitude and longitude and a UT (GMT) and it gives Hc and Zn for every visible body. Great, very useful page!
But it does not do "sight reduction" in the sense of taking a hs and reducing it to a Ho and then calculating a corresponding Hc which, of course, one needs to do to develop a line of position.
If you want the "whole package" (Hc and Ho, Zn and a), may I suggest downloading "Celestial Tools" written by list member Stan Klein? You can find a link to download it at the United States Power Squadrons' web site:
http://www.usps.org/national/eddept/n/tools.htm#celtools
as well as in previous posts by Stan.
The results are presented in a format similar to USPS's sight reduction form found at
http://www.usps.org/national/eddept/n/downloads.htm#worksheets
(look for Sight Reduction Form SR96a near the bottom of the page)
which is a pretty straightforward form leading one through the steps of calculating both Ho from your observation and Hc from Nautical Almanac data.
Lu
At the USNO site (for which several have sent the URL), you enter your latitude and longitude and a UT (GMT) and it gives Hc and Zn for every visible body. Great, very useful page!
But it does not do "sight reduction" in the sense of taking a hs and reducing it to a Ho and then calculating a corresponding Hc which, of course, one needs to do to develop a line of position.
If you want the "whole package" (Hc and Ho, Zn and a), may I suggest downloading "Celestial Tools" written by list member Stan Klein? You can find a link to download it at the United States Power Squadrons' web site:
http://www.usps.org/national/eddept/n/tools.htm#celtools
as well as in previous posts by Stan.
The results are presented in a format similar to USPS's sight reduction form found at
http://www.usps.org/national/eddept/n/downloads.htm#worksheets
(look for Sight Reduction Form SR96a near the bottom of the page)
which is a pretty straightforward form leading one through the steps of calculating both Ho from your observation and Hc from Nautical Almanac data.
Lu
From: Geoffrey Kolbe <geoffreykolbe@compuserve.com>
To: luabel@ymail.com
Sent: Thursday, December 26, 2013 10:01 PM
Subject: [NavList] Online sight reduction program
If memory serves, the US Navy used to have a site which did sight reductions and used its own calculations for the positions of the celestial bodies. So, all you had to do was enter the celestial body for the sight, the estimated long and lat, and the time. I think that site is no longer, and I wonder if anyone knows of any equivalent out there?ThanksGeoffrey Kolbe--: http://fer3.com/arc/m2.aspx?i=125949
