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
    Name or NavList Code:
    Email:
       
    Reply
    Re: Parallax of the Moon
    From: Gary LaPook
    Date: 2015 Feb 7, 08:13 -0800
    Hey Stan, don't be too hard on yourself, we've all been there.

    gl


    From: Stan K <NoReply_StanK@fer3.com>
    To: garylapook@pacbell.net
    Sent: Saturday, February 7, 2015 2:11 AM
    Subject: [NavList] Re: Parallax of the Moon

    Please ignore all messages from me with the subject "Parallax of the Moon".  To start with, I did not give all the information required in the original question.  Then.more mistakes.  I should not be doing this when I should be sleeping.  Now I almost have my head removed from my butt, but not quite.

    Stan




    -----Original Message-----
    From: slk1000 <slk1000---.com>
    To: slk1000 <slk1000---.com>; navlist <navlist@fer3.com>
    Cc: ronandsandy <ronandsandy{at}olympus.net>
    Sent: Sat, Feb 7, 2015 4:44 am
    Subject: Re: Parallax of the Moon

    Uh oh...  Now I'm not so sure.


    -----Original Message-----
    From: slk1000 <slk1000---.com>
    To: navlist <navlist@fer3.com>
    Cc: ronandsandy <ronandsandy{at}olympus.net>; slk1000 <slk1000---.com>
    Sent: Sat, Feb 7, 2015 2:47 am
    Subject: Re: Parallax of the Moon

    I asked this question a couple of days ago and I cannot believe I have not received one response.  Dozens of responses on "Irregular Quadrilateral Center" and "Japanese Sextant 1979", but none on this question.  Well, last night I was sitting on the couch watching Hawaii Five-0 when I had an epiphany.  I was using the formula on page 280 of the Nautical Almanac, PA = HPcosH+OB, where HP is the horizontal parallax, H is the apparent altitude (sextant altitude corrected for index error and dip, H = Hs + I - D), and OB is the correction for the oblateness of the Earth.  It might be said that the first part of the formula, HPcosH, is just an approximation, but it is a very good approximation.  The problem is much more basic than that.  THE FORMULA IS INCORRECT!  Now I will play Frank Reed and challenge you to tell me why.  It is really pretty simple once you give it a little thought.

    Stan



    -----Original Message-----
    From: slk1000 < slk1000---.com>
    To: navlist < navlist@fer3.com>
    Cc: slk1000 < slk1000---.com>
    Sent: Thu, Feb 5, 2015 6:07 pm
    Subject: Parallax of the Moon

    The attachment is part of an output from the USNO Celestial Navigation Data web page.  Can anyone tell me how the USNO gets a parallax value of 15.6'?  Every other source I tried got about 15.27', but 15.6' is the only one that makes the numbers agree with the Moon Altitude Correction Tables in the Nautical Almanac.

    Stan




       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Get a NavList ID Code

    Name:
    (please, no nicknames or handles)
    Email:
    Do you want to receive all group messages by email?
    Yes No

    A NavList ID Code guarantees your identity in NavList posts and allows faster posting of messages.

    Retrieve a NavList ID Code

    Enter the email address associated with your NavList messages. Your NavList code will be emailed to you immediately.
    Email:

    Email Settings

    NavList ID 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