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: Lewis and Clark lunars: more 1803 Almanac data
    From: Ken Muldrew
    Date: 2004 Apr 17, 08:25 -0600

    > The rate in the almanac data is geocentric. You would have to
    > calculate the apparent topocentric rate incorporating changing
    > parallax and refraction in order to compare against the observed rate.
    
    You're right, of course. My thinking was that an estimate of the angle
    formed by the line connecting the moon and Aldebaran, as well as the
    line connecting the moon and the mystery star, even if it was out by 5?,
    taken together with the measured distance, would lead to one, or at
    most, two stars that could possibly be misidentified as Aldebaran (and
    even then, only with partly overcast conditions). This process would
    basically give two regions-of-interest, one North and one South of the
    ecliptic in which to search for candidate stars.
    
    > And:
    > "It's pretty hard to misidentify either Aldebaran or Rigel."
    >
    > Although I don't think one can reach the conclusion that they
    > misidentified their star *yet*, it is a real possibility. For anyone
    > trained in celestial navigation in the past 75 years identifying the
    > stars is part of the game. But back then it wasn't. Stars were rarely
    > used by navigators in the 19th century *except* the nine lunars stars.
    > Bowditch and other navigation manuals included little charts and
    > descriptions for these stars and no others. Certainly many people
    > learned the constellations for their own amusement, but those who did
    > not would have a tough time picking out the right stars until they
    > accumulated some serious experience.
    
    This comes as quite a surprise. I would have thought that everyone
    would have at least a passing familiarity with the constellations of the
    zodiac and a few of the more obvious ones (such as Orion, Ursa Major,
    etc.) in the era before streetlights. If what you say is true, then I think it
    increases the likelihood of the hypothesis that another star was
    misidentified as Aldebaran.
    
    Ken Muldrew.
    
    
    

       
    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