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: Aldebaran occultation
    From: Paul Hirose
    Date: 2017 Mar 7, 11:05 -0800

    On 2017-03-07 9:13, Brad Morris wrote:
    > Alex notes his time of occultation at 3h56m48s.
    > Paul, using up to the minute tools, makes that "4 seconds earlier" at
    > 3h56m44s.
    Actually my Lunar4 program was not designed for serious occultation
    computations. For simplicity it assumes the Moon's limb is a perfect
    circle. That's why I gave results to only .01′ precision, and I'm not
    confident about the last digit.
    However, I've never tested the program against the IOTA predictions,
    which I assume include all the refinements. At IOTA's nominal
    Indianapolis site the Aldebaran lunar distance errors from Lunar4 are
    +.014′ (begin) and +.012′ (end), but those are only two points on the
    limb. I want to try more points, and more than one occultation to get
    some variation in libration angles.
    Don't expect a lunar limb model in Lunar4. I don't think it's worth the
    bother. But the next release may include a small change in Moon radius.
    Currently I use the IAU value, 1737.4 km. Based on private
    correspondence with another enthusiast, I believe 1738.0 km is a better
    fit to the mean limb visible from Earth. That would eliminate about half
    the error in the values above.

    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