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
    or...
       
    Reply
    Re: Lunars Calculator (ver. 4)
    From: Frank Reed
    Date: 2008 Dec 4, 07:32 -0800

    Dave W., you asked:
    "In the calculator, are the planet distances to center, COI, near, or far?"
    
    In keeping with traditional practice, the distances are to the planet's 
    geometric center. So when you shoot a lunar using Jupiter, bring the planet 
    to the Moon's limb and split it. 
    
    Venus is a problem. When Venus is near the Earth, it has a large apparent 
    diameter and also a significant phase. The best approach that I can think of 
    here is to find out the phase of Venus in advance, and attempt to "visualize" 
    the planet's center in the tiny crescent visible with the sextant telescope. 
    Alternatively, you could attempt to make the limbs match and then subtract or 
    add the semi-diameter of Venus from the sight (for Venus the semi-diameter is 
    very nearly equal to the horizontal parallax on the given date since Venus 
    has nearly the same physical diameter as the Earth). Either approach is extra 
    work. It saves a lot of trouble if you just ignore Venus when it's a 
    crescent. That's what I do.
    
    -FER
    
    
    --~--~---------~--~----~------------~-------~--~----~
    Navigation List archive: www.fer3.com/arc
    To post, email NavList@fer3.com
    To unsubscribe, email NavList-unsubscribe@fer3.com
    -~----------~----~----~----~------~----~------~--~---
    

       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Join NavList

    Name:
    (please, no nicknames or handles)
    Email:
    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:

    Email Settings

    Posting 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