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: Green Flash and Longitude
    From: Bruce Stark
    Date: 2006 Jan 6, 13:49 EST
    Frank and Doug,

    No, I haven't seen the Green Flash, but if I happened to I'd probably count seconds until picking up time from the watch, so as to have the Greenwich time of the event. The flash itself would give local time, thus longitude. It would be an interesting stunt, nothing more. 

    Dip, refraction and semidiameter, plus 90 degrees, would give the sun's zenith distance. You could work it either as a time sight or LOP. Azimuth for the LOP could be had by adding or subtracting the amplitude from 270 degrees, maybe allowing a bit for the sun's change of azimuth between the time it was on the celestial horizon and the time of sunset.

    Considering how inaccurate the method could be, due to uncertain refraction, it might do to get local time simply by interpolating the times of sunset given in the Almanac.

    Unfortunately I can't recall reading anything about getting longitude from the Green Flash, but it's hard to believe it hasn't been proposed at various times, at least as a curiosity.

    Bruce
       
    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)