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: Lat and Long by moon transit.
    From: Hewitt Schlereth
    Date: 2011 Jan 29, 12:33 -0400
    Hi Antoine -

    To figure the latitude, I took Jeremy's highest Hs at 09-50-00 of  55° 27.5' and came up with  21° 45.0' N. Moving this to account for his ship's movement, gave me 21' 47.1' N at 1000.  (21° 48.7 N = GPS at 1000 GMT). So, I have him 1.6' south of the GPS. (You have him at 21° 47.6' N).

    Since the altitudes were taken very close to meridian passage and were changing only a few tenths/min, I was a little dubious about how my paper-and-pencil method for longitude would turn out.

    Anyway, I took the two equal altitudes - 55° 25.6' at 09-48-15 and 09-55-19 - averaged the times, and came up with an uncorrected longitude at 09-51-47 of 130° 02.1 E.  Applying the correction of .7' for ship's net motion of .4 kts directly toward the moon, gave me a longitude of 130° 01.4' E. Accounting for the ship's movement south and west between 0950 and 1000 gave a 1000 longitude of 130° 03.5' E. So, I have him 4.0' of longitude west of the GPS position of 130° 07.5' E. (You have him at 130° 03.2' E).

    You and I agree to 0.5' of latitude and 0.8' of longitude.

    For some reason your attachment came up scrambled on my Mac (was it doc.x?), so I don't know how this compares with others' results.

    Best regards.  Hewitt


    On Sat, Jan 29, 2011 at 4:19 AM, Antoine Couette <antoine.m.couette{at}club-internet.fr> wrote:

    RE :
    http://www.fer3.com/arc/m2.aspx?i=115506
    [NavList] Re: Lat and Long by moon transit.
    From: hhew36---com
    Date: 28 Jan 2011 20:27

    IT DID IT AGAIN : THIRD and LAST attempt since some text by the end of my post got suppressed on first two trials. This time, I have slightly modified the arrangement of the end of my text, and did not include the Annex which was transmitted OK on the first 2 trials. Will it go thru entirely this time ???

    Kermit


    *******


    Dear Hewitt,


    You wrote : "Looking at Kermit's results, I'd say he used the 6-30-2009 date."

    I will reply as follow :
    YES ! I used the 6-30-2009 (UT) date, with LT-UT = +9 , which was subsequently confirmed as correct by Jeremy.

    And for the time of the Moon Transit (UT=09h51m39.7s), I am getting the following data for the Moon :

    GHA = 229°56'3 with RA hourly change = +0°.5064 and

    DEC = S-12°38'7 with DEC hourly change = -12'.86

    The actual Moon declination on 6-30-2009 was (much) further to the South than what Jeremy first indicated : QUOTE The declination is about 7 degrees south UNQUOTE, which tells us that Jeremy's clue would actually have been more appropriate for 6-29-2009 as you say, but it was nevertheless quite "valid" for 6-30-2009 in the sense that the Moon was - for both dates - South of the 6-30-2009 Observer's Position.

    Hewitt, since in your subsequent post (RE : http://www.fer3.com/arc/m2.aspx?i=115508) you indicated : QUOTE Thanks, Jeremy,, that clears it up nicely, -Hewitt UNQUOTE, which results are you getting for this Moon LAN ?

    I would guess that all of us - yourself, Peter, Andres, Kermit, and others - should derive (almost) the same end result (see my enclosed listing of entries and results : NOT INCLUDED IN THIS THIRD SENDING TRIAL), even with a plain parabolic fit to Jeremy's data which certainly should be fully appropriate here given both the "moderate" (55 degree) Culmination height and the rather "tight" (+/- 12 minutes of time) time-span around Culmination Time in this specific example.


    Best Regards


    Kermit


    Antoine M. "Kermit" Couëtte

    LAST NOTE TO THE ATTENTION OF FRANK E. REED : Now and then, I have noticed that some of my posts get "shortened/abridged" by your NavList Computer system. Any clue or reason for that, Frank ?


    ----------------------------------------------------------------
    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