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: Ulugh Beg's sextant
    From: Frank Reed CT
    Date: 2006 Mar 26, 18:05 EST

    Herbert, you wrote:
    "E. B. Knobel  investigated the accuracy of Ulugh Beg's star catalogue in
    the introduction  to his edition of it. After grouping the stars into
    northern, zodiacal and  southern ones, he shows a systematic bias in
    longitude of 18', 14' and 4'  respectively. Then he subdivides each group
    into 18 sub-groups, each 20 deg  of longitude wide. The corresponding
    errors in longitude fluctuate about a  quarter of a degree around those
    means, occasionally a little more.  Therefore, some longitudes are more
    than half a degree off the truth.   The errors in latitude are of a
    similar magnitude. From what I see, they may  be just marginally better
    than those of Ptolemy/Hipparchus."
    
    Very  interesting. Thanks. It strikes me that the accuracy in latitude should
    be  better than that in longitude. No?
    
    What is the origin of this myth that  the positions were accurate to a few
    seconds of arc? A number of web sites quote  an article by "Kevin Krisciunas" on
    this point. Maybe it's just that single  source.
    
    -FER
    42.0N 87.7W, or 41.4N  72.1W.
    www.HistoricalAtlas.com/lunars
    
    
    

       
    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