NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Lunar distance accuracy
From: Alexandre Eremenko
Date: 2007 Oct 23, 22:26 -0400
From: Alexandre Eremenko
Date: 2007 Oct 23, 22:26 -0400
Frank, Indeed, I missed the paper of White. Thanks for sending me a link. I am collecting experimental data on Lunars accuracy, and will soon post the combined statistics. Alex On Tue, 23 Oct 2007 frankreed@HistoricalAtlas.net wrote: > > > Alex, you wrote: > "These are all data I have. I will be very grateful if someone points to any > other hard data or research on the subject." > > You may have missed the article by E.J. White from 1889 that I described on > the list almost a year ago --I know you get busy now and then and don't > follow the list as closely as you would like. Here's a paragraph from my > post back then: > > "White then details the lunar distance observations he has made in the past > three years: forty-two lunars in 1887, 1888, and 1889. He lists the time and > measured distance (only approximately, not enough detail to re-work them > today) and also lists the error of the resulting longitude in seconds of > time. We can convert this to an approximate error in the measured lunar by > dividing by 120. That is, an error of 12 seconds in the longitude is > approximately equivalent to an error of 0.1 minutes of arc in the measured > lunar distance. Calculating from his listed numbers, I find he has a > standard deviation in Greenwich time of about 30 seconds which is equivalent > to about 0.25 minutes of arc in the lunar distances. If we take his lunars > in sets of four and average them (which I consider the best approach with > lunars), the results are generally within 0.1 minutes of arc. I would note > that these results are very similar to my own experience." > > The original post is here: > http://fer3.com/arc/m2.aspx?y=200611&i=101759 > > As noted then, I found White's article originally while digging around in > Google Books. Since it's short, I've also made it available on the web here: > www.HistoricalAtlas.com/lunars/ejwhite. > > -FER > www.HistoricalAtlas.com/lunars > > > > > --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to NavList@fer3.com To , send email to NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---