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
Message:abc
Add Images & Files
    Name or NavList Code:
    Email:
       
    Reply
    Re: Sun sights during an eclipse: "bad limb" calculation
    From: Geoff Hitchcox
    Date: 2023 Oct 7, 03:17 -0700

    In my last post, I gave the following output of the JPL Horizons Ephemeris. 

    Date__(UT)__HR:MN:SC.fff, , ,Azi_(a-app), Elev_(a-app),  Ang-diam (arc seconds),
    2023-Oct-14 18:20:40.000,*,m, 193.862553,    52.525591,  1828.926, MOON position
    2023-Oct-14 18:20:40.000,*,m, 194.280049,    52.793284,  1924.160, SUN position
    I then just happened to use Frank's USNO clone ephemeris to check the above numbers, and suddenly found that the SUN was OK, but the Elev of the Moon was out by more than half a degree. A quick check using other sites, showed that Frank's ephemeris was correct, and so it was Horizons that was giving inaccurate elevations for the Moon. As a clue that some parameter was wrong at Horizons, the "declination" of the Moon was out by a similar amount.
    Pasadena we have a problem !
    A few quick checks at other times and places on the Horizons site  (for the Moon) showed a consistent more than a half degree error in generating the Elevation (Azimuth appears OK). In the meantime, I guess I have to wait, to see if the problem is resolved overnight, or does someone on Monday have to "Turn it OFF and turn it ON again".
    So my playing with lots of number crunching - will have to wait a while.
    Regards, Geoff Hitchcox, Christchurch, New Zealand.
       
    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