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: Time zone confusion
    From: John Huth
    Date: 2011 Oct 23, 11:16 -0400
    John B.- 

    Yes, I agree that time zones are confusing, and constantly shifting.   As many have pointed out on the list, the timezone issues are mainly centered on commerce or political needs, although the 'intent' is presumably to place the sun roughly overhead at local noon.  

    I'm giving my students an exercise this coming week to take a set of sights of the sun and use the equal altitude method to get longitude (it's a basic course, so I use very simple methods).   One of the bigger confusions they have is the step of going to UTC from our eastern daylight time - because I have to explain the nature of the shift, and even the distinction between EDT and EST.  That's probably the most difficult aspect of the entire exercise.   

    One problem I have is that some of my experimental group is located in Geneva, Switzerland.   The shift from daylight to standard time usually differs between Europe and the US by about a week, so we go from a 6 hour time difference to a 5 hour time difference, and our video conferences all get confused, as do phone calls and such.

    John H. 

    On Sun, Oct 23, 2011 at 11:03 AM, John Brown <jdb0302@yahoo.co.uk> wrote:

    I have recently seen several maps showing the world divided into time zones, but the zone labels are inconsistent, with either negative or positive signs used for the same hemisphere.

    Of course, it is not difficult to see how to get UT from ZT and vice-versa, but a simple reference to, say ZT-6, can refer to a time/location in easterly or westerly longitude, depending upon which map one prefers. This is a bit like the common confusion between the sign of an error and its correction.

    It seems logical to use cartesian labelling with westerly time zones as negative, but others disagree. Is there an internationally recognised convention on this? Consulting my usual references is not much help.

    When I was at sea we took no notice of "official" zone time and just adjusted the ship's clocks as necessary to locate lunchtime somewhere in the middle of the day.

    Regards to all
    JB
    ----------------------------------------------------------------
    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
    ----------------------------------------------------------------




    --
    Keeping up with the grind
       
    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