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: Latitude and longitude around noon
    From: Rafal O.
    Date: 2017 Mar 8, 23:57 -0800

     Below are my calculations of latitude and longitude. To calculate time of LAN I used the fact that near this moment trajectory of Sun is like parabola or, in other words, quadratic function:

        Hs(t) = a*(t - t0) + hs
        Hs(t) = a2*t^2 + a1*t + a0

    Using programable calculator that allows to estimate these three parameters (a, t0, hs) or (a2, a1, a0) one can obtain both time of LAN and height of Sun at this moment. I used R program but programable calculator gives t0 and hs as -a1/(2*a2) and a0/a2.

    Here I present output of R:

    Formula: Hs ~ a * (t - t0)^2 + hs

    Parameters:
        Estimate Std. Error  t value Pr(>|t|)  
    t0 16.968047   0.002869  5914.69  < 2e-16 ***
    hs 41.492687   0.003912 10607.49  < 2e-16 ***
    a  -1.919479   0.045020   -42.64 1.02e-09 ***
    ---
    Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

    Residual standard error: 0.008542 on 7 degrees of freedom

    Number of iterations to convergence: 3
    Achieved convergence tolerance: 3.286e-07

    Hence, time of LAN is 16.968047 UTC (16:58:05 UTC) and Hs 41°29.6'. For Sun LL Hc has value of:
    Hs[noon] = 41 29.6
    IC       =    -3.8
    dip      =    -4.8
    Ha[noon] = 41 21.0
    LL       =   +15.2
    Hc[noon] = 41 36.2

    From Air Almanac Sun is due south at 12:12:05 UTC. Time differene is 4:46:00 which corresponds to 71°30.0' W. Declination of Sun at this moment is 7°01.2' S. From this one can calculate Lat as 41°22.6' N.

    So, the position in question is: 41°22.6' N, 71°30.0' W.

    Yours sincerely,
    Rafal O.

       
    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