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: Navigation Spreadsheets in 2022
    From: Frank Reed
    Date: 2021 Dec 10, 10:15 -0800

    Before I forget, to see an example of the issue with the proper motion of Rigil Kentaurus (alpha Centauri), try this: open Stellarium, go to Rigil K. and zoom in until you can see that it is a double star. Now fix the app's attention on that star by tapping space bar on your keyboard. You may also want to turn off the atmosphere and ground. Open the date and time selection tool and increment or decrement the year. You can do this by putting the cursor on the year and then hitting "+" or "-" on the keyboard. Hold the key down to run through a few centuries. If the app handled this system properly, it might manage with two options: either do the orbital motion of A and B around their common center of mass, which would be the best choice, or keep the two stars at a fixed separation and have them both follow the correct center of mass proper motion. Instead the stars have independent proper motions, which are presumably the values derived from the original Hipparcos analysis, and they behave as if they are gravitationally unbound. The two stars in the system separate at a rate of about 0.8 minutes of arc per century. This is not good.

    Frank Reed

    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