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: Refraction
    From: Robert Eno
    Date: 2005 Aug 5, 22:36 -0400

    George wrote:
    > By the way, several of those responses from Roibert Ene were misdated to
    > have a September date rather than an August one. I hope he will correct
    > his
    > calender, because my email reader, which puts correspondence into strict
    > date order, keeps mis-sorting Robert's contributions.
    > ==============
    Yes, thanks George. I caught that yesterday and made the change. Don't know
    how it got advanced a month.
    George wrote:
    > That seems a bit odd, and unphysical. From a height of 0 feet, how can a
    > sextant altitude possibly be -1degree? Also, the quoted value for the
    > correction, at -35 minutes, is rather a surprise, considering that the
    > adopted value for refraction at 0 degrees altitude is -34 minutes, and
    > refraction increases very quickly as the altitude decreases towards zero.
    Robert responds,
    Quite correct George.  The entry arguments for the altitude of the observer
    are in increments of 5000 feet, starting at 0. So those refraction figures
    that I quoted apply (presumably) to altitudes of from 0 - 4999 feet.
    Obviously this is a table for air navigation, so I would imagine that the
    corrections were intended for altitudes well above sea level.

    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