Welcome to the NavList Message Boards.


A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Add Images & Files
    Re: Online Nautical Almanac
    From: Gary LaPook
    Date: 2011 Feb 13, 10:43 -0800
    All I can say is "keep shoveling."

    The essence of the "noon sight" is that you don't know the actual time of noon in advance since your estimate is based on you DR longitude. Prior to chronometers they still used the "noon sight" for latitude even though they measured time with only a calender.

    If you want the exact time of LAN at your location it is easy enough for you to do with your almanac and the time should be between about 1745 Z and 1810 Z at your location as the equation of time varies during the year. To calculate this you start with the longitude of your location (you do have a gps, don't you, if not use Google Earth) and subtract the GHA of the sun from it using either 1700 or 1800 Z, whichever is less than and closest to your longitude. Take this remainder and run down the increments table until you find the time period that results in this remainder and add that time to 1700 or 1800 Z that you started with.

    If you just want it to a one minute accuracy so that you know approximately what time you should start standing out in the cold then you can use the time of meridian passage from the Nautical Almanac adjusted for the difference between your longitude and the longitude of the standard meridian for your time zone, 90° west in your case. Your noon should occur about 9 minutes before the listed times.

    For the dates you listed:
    Feb 19  1214
    Feb 20   1214
    Feb 26  1213
    Feb 27  1213
    Mar   5   1212
    Mar  6     1211

    The online almanac at tecape doesn't have this auxiliary data.


    --- On Sun, 2/13/11, Matthew G. Ashbrook <ash13brook@gmail.com> wrote:

    From: Matthew G. Ashbrook <ash13brook@gmail.com>
    Subject: [NavList] Re: Online Nautical Almanac
    To: NavList@fer3.com
    Date: Sunday, February 13, 2011, 7:10 AM

    I'm in the far South suburbs - Monee on I-57, 10 sm S. of I-80.
    I expect that I'll just practice with what I can. I'm probably not going to convince my wife I need afew hundred bucks worth of mercury so soon after I convinced her that I needed an Astra III!
    Here's what I'm looking for an online almanac for. So far, the only thing I know how to do is figure LAN. I've found some calculator type almanacs and I have a Long Term Almanac through Starpath, but none have Mer Pass of the sun - at least I haven't been able to find it.
    I'm ordering the books I need as soon as I get a recommendation from Starpath on what I need, but in the meantime, if someone could give me the Mer Pass of the sun for the following dates, I would be good for awhile:

    Saturday, Feb 19
    Sunday, Feb 20
    Saturday, Feb 26
    Sunday, Feb 27
    Saturday Mar 5
    Sunday, Mar6

    Matt Ashbrook

    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

    Browse Files

    Drop Files


    What is NavList?

    Join NavList

    (please, no nicknames or handles)
    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 Settings

    Posting Code:

    Custom Index

    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