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: Measure the Sun's diameter
    From: Frank Reed
    Date: 2013 Jan 7, 11:05 -0800

    I forgot another bit of advice. Nine years ago, in one of my first posts on lunars, I described holding the sextant with both hands and adjusting the micrometer separately, as follows:
    "I usually do the lunars observations themselves with both hands on the sextant frame since the angle at which you have to hold the sextant is often awkward --and even painful after a few minutes. Holding he instrument stably is critical. To make this work, I would alternate between adjusting the sextant angle, making small adjustments of the micrometer, with the actual process of looking through the sextant. The lunar distance changes so slowly that you don't really need to keep a hand on the micrometer while observing (as is essential with altitude observations)."

    This was a rather long post which I rather enjoyed re-reading just now. I recommend it! ;) You can read it here:
    http://fer3.com/arc/m2.aspx/long-lost-lunars-FrankReed-dec-2003-w12326

    My comment above about tweaking the micrometer and then looking through the sextant with both hands on the frame applies even more so to the measurement of the diameter of the Sun since it doesn't change for days. This process is much less stressful than ordinary altitude observations. You're not chasing a rapidly moving body, trying to swing the arc, and trying to make sure you've got the horizon in proper view (not hidden by a swell, as it may be from the deck of a smaller vessel). In this respect, lunars are actually EASIER observations than common altitude observations. You don't have to worry about the horizon, and there's much less rush involved.

    -FER


    ----------------------------------------------------------------
    NavList message boards and member settings: www.fer3.com/NavList
    Members may optionally receive posts by email.
    To cancel email delivery, send a message to NoMail[at]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