Welcome to the NavList Message Boards.


A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Add Images & Files
    Re: Real life accuracy...my experience, how does it compare...
    From: Frank Reed
    Date: 2015 Aug 24, 14:07 -0700

    Hello Mark,

    Welcome aboard! You're a fellow lunarian and a southern New Englander, too. As you may know, I teach the celestial navigation classes at the Treworgy Planetarium at Mystic Seaport, including a class in "Lunars" which will be offered again this fall.

    A couple of thoughts:

    • I would say that your range in IC values is not bad. If you're saying that you get 0.7-0.9 minutes of arc with some consistency, that's plenty good enough, at least for now.
    • You mentioned checking your time against UT from a GPS receiver and then adding DUT1. This latter step is totally un-necessary. Since DUT1 is only a fraction of a second, you would need to be able to measure lunar distance arcs to apprximately 0.01 minutes of arc before you would worry about DUT1.
    • How are you working up your lunars? Have you tried my online lunars tools?
    • You say you're getting errors of 4 minutes and sometimes 8 minutes. Are those errors in the observations by minutes of arc or errors in the computed GMT by minute of time. It's roughly two-to-one regardless (1' error in measured arc yield 2 min error in absolute time). I would count these as mediocre results. You can expect much better. You need to narrow down the origin of the inaccuracy: sextant? sight-taking methodology? Clearing process? Something else?

    Again, welcome aboard.

    Frank Reed
    Conanicut Island USA (southern end... in sight of Block Island)


    Browse Files

    Drop Files


    What is NavList?

    Join NavList

    (please, no nicknames or handles)
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.

    Email Settings

    Posting Code:

    Custom Index

    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site