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: Curious star charts
    From: Alexander Duytschaever
    Date: 2020 Nov 20, 07:37 -0800

    The number at the bottom center seems to be a Right Ascension reference.

    Looking at slide with RA19.0 labeled at the bottom, it seems that the delta time from Altair (~0:17) to Sirius/Procyon (~0:58) is 0:41. On a star map, that distance covers (along a great circle, the center lines look like great circles) ~170 degrees, which makes 360 degrees cover in 1h26m. 

    According to https://keisan.casio.com/exec/system/1224665242, this would represent an orbit of about h=90km.

    Some ideas that crossed my mind:

    • 90km seems to be called the "Karman Line", limit of atmosphere
    • SR71? too low (up to 100kft = 33km)
    • some kind of Moon orbit tool (Apollo? Lunar Escape System?), but these start at 1.8h = 1h48m
    • short range ballistic missile defence?

    It might be good to add a known object or a ruler to the pics, to get an idea of scale.



    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