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: Predicting transit using Bowditch section 2010
    From: Jim Thompson
    Date: 2003 Dec 22, 15:55 -0400

    I second that.
    
    By the way, below is my prediction for transit of the sun from the east end
    of the Dominican Republic on February 3/04.  All 3 methods give the same
    answer.
    
    The sun and stars line up very nicely for my compulsory evening twilight
    3-body sight while we are down there for a week of R&R.  I hope Customs in
    the DR doesn't balk at the sextant and GPS unit in my luggage.
    
    Jim Thompson
    jim2{at}jimthompson.net
    www.jimthompson.net
    Outgoing mail scanned by Norton Antivirus
    -----------------------------------------
    
    > -----Original Message-----
    > From: Navigation Mailing List
    > [mailto:NAVIGATION-L{at}LISTSERV.WEBKAHUNA.COM]On Behalf Of Fred Hebard
    > Sent: Monday, December 22, 2003 3:27 PM
    >
    > Doug,
    >
    > Having somebody present these techniques is precisely why I am on this
    > list.  If you can, I would appreciate hearing of any you wish to share.
    
    Punta Cana Predicted Transit Sun on Feb 3/04
    12h  47m 14s
    
    Airport
    L 18d 34.584' = 18.5764d
    Lo 68d 21.804' = 68.3634d
    
    Method 1:
    L 18d 34.584' = 18.5764d
    Lo 68d 21.804' = 68.3634d
    GHA 68.3634d
    Next lowest GHA 561d 33.3' = 56.5550
    Whole GMT hour of lower GHA = 16
    DLo 68.3634 -  56.5550 = 11.8084d
    Increment 11.8084d = 11d 48.5' = 47m 14s
    => Time of transit GMT = 16h  47m 14s
    ZD +4
    Time of transit ZT = 12h  47m 14s
    
    Method 2:
    Meridian Passage almanac = 12h 14m that day.
    DLo 8d 21.8' = 33m 27s past central meridian = 33 min.
    => Transit is 12h 47m +/- 1 minute.
    
    Method 3:
    Greenwich:
    Lo 00d 00.0' = 00.0000d
    GHA 00.0000d
    Next lowest GHA 356d 33.6' = 356.5600
    Whole GMT hour of lower GHA 12
    DLo 360.0000 - 356.5600 = 3.4400d
    Increment 3.4400d = 03d 26.4' = 13m 46s
    =>Time of transit GMT = 12h  13m 46s which rounds to Almanac's 12h 14m.
    ZD +0
    Time of transit ZT at Greenwich = 12h  13m 46s.
    Add DLo 8d 21.8' = 33m 27s past central meridian.
    Time of transit ZT at Airport = 12h  47m 13s.
    
    EqT = (shaded so negative value)
    1200 -13m 46s
    0000 -13m 52s that night
    1600 -13m 48s interpolated
    Subtact EqT from GMT to get GAT, since meridian passage is after 1200, but
    since EqT is negative, then add its absolute value to GMT to get GAT, which
    is logical.
    
    
    

       
    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