Welcome to the NavList Message Boards.

NavList:

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

Compose Your Message

Message:αβγ
Add Images & Files
    Name or NavList Code:
    Email:
       
    Reply
    Re: Eclipse computations with Lunar4
    From: Frank Reed
    Date: 2016 Oct 11, 11:14 -0700

    Paul Hirose, you wrote:
    "For utmost accuracy, check the "Moon center of figure correction" box. It applies the standard correction of +.5″ longitude and -.25″ latitude to the center of gravity positions that you get from an ephemeris. The Astronomical Almanac eclipse data includes this correction, but I don't think it's important and in fact didn't use it in the above computations."

    Straight out of the 1950s! Unfortunately, this center of figure correction is seriously antiquated. With or without it, you will not get the sort of accurate eclipse data that will be relevant to resolving minor disagreements over the duration of next summer's eclipse. We now have highly accurate DEM (digital elevation model) data for the lunar surface, derived from unmanned spacecraft observations in the past decade. Despite the enormous and impressive effort you have put into your "Lunar4" software, you have neglected the single most important advance in lunar timings in a century. To address this deficit, you'll have to abandon your peculiar design principle of making your product smaller than a megabyte (which matters to no one in the world, except as a stunt, in the year 2016), but in principle it's not too difficult. This could potentially make your prediction data world-class. You're only one step away. I do understand that this involves "getting into the dirt" of the Moon --literally. Many people who enjoy creating astronomical software balk at the unpleasantness of mountains and valleys on the lunar surface. It's so un-astronomical. But fear not! It's a nice clean dataset amenable to the same exacting calculations and geometric principles that provide pleasure in more ethereal astronomical computations.

    Frank Reed
    Conanicut Island USA

       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    NavList is a community devoted to the preservation and practice of celestial navigation and other methods of traditional position-finding. We're a group of navigators, navigation enthusiasts and hobbyists, mathematicians and physicists, and historians interested in all aspects of navigation but primarily those techniques which are non-electronic.

    To post a message, if you are already signed up as a NavList member, start a new discussion or reply to any posted message and use your posting code (this is a simple low-security password assigned when you join). You may also join by posting. Your first on-topic messsage automatically makes you a member, and a posting code will be assigned and emailed to you for future posts.

    Uniquely, the NavList message boards also permit full interaction entirely by email. You can optionally receive individual posts or daily digests by email, and any member can post messages by email (bypassing the web site) by sending to our posting address which is "NavList@NavList.net". This functionality is similar to a traditional Internet mailing list: post by email, read by email, reply by email. Most members will prefer the web interface here for posting and replying to messages.

    NavList is more than an online community... more about that another day.

    © Copyright notice: please note that the rights to all messages and posts in this discussion group are held by their respective authors. No messages or text or images extracted from messages may be reproduced without the explicit consent of the message author. Email me, Frank Reed, if you have any questions.

    Join / Get NavList ID Code

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

    A NavList ID Code guarantees your identity in NavList posts and allows faster posting of messages.

    Retrieve a NavList ID Code

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

    Email Settings

    NavList ID Code:

    Custom Index

    Subject:
    Author:
    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