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: Will the Nautical Almanac Survive?
    From: Frank Reed CT
    Date: 2006 Mar 30, 15:49 EST

    Robert Eno wrote:
    "For how much longer will  the US Government publish the Nautical Almanac?"
    I think it's impossible  to say. It's not very expensive, so I would guess it
    will be around for a while  longer. But let's suppose both the US Govt and
    the UK govt decide to kill  funding for the nautical almanacs completely. What
    happens next? The ephemeris  data for all of the objects we observe is already
    available for the next few  centuries at a level of accuracy higher than that
    required by celestial  navigation. The refraction tables, dip tables, etc. can
    be re-calculated by  anyone who cares to do it. There is only one quantity
    that needs to be  re-determined every few years: delta-T, that slowly changing
    difference between  a true time standard (like atomic clocks) and the time
    shown by the rotation of  the Earth. Fortunately, this quantity is of interest for
    many constituencies  today so it's still watched closely and published
    regularly. Even if it were  not, it is observable with ordinary sextant observations
    as long as a  near-perfect time standard is available (the time on an average
    cell phone is  accurate within a fraction of a second).
    I would guess that if we wanted  to publish a commercial "Nautical Almanac"
    with absolutely no support from  government sources (except the ephemeris data
    which is alredy available on the  Internet today), we could have it up and
    running and published in almost exactly  the same format as the current
    government editions within six months.
    "will we eventually reach a point where the Nautical Almanac  will no longer
    be available as a printed document - commercial or  government-produced --
    but as a computer program with printable tables? I  sure hope not but it seems
    to me that the world is fast going paperless and  electronic."
    If you're willing to buy a paper almanac, then someone will  sell you one.
    But how long are you going to be at sea? If you're going for two  weeks, perhaps
    you would like pages printed specifically for those days instead  of the
    entire year. Home-computer printing seems like a better option in that  case.
    "For that matter, will there still be a practical  requirement for
    observatories to collect and calculate astronomical ephemeris  data. Certainly these
    data will likely be maintained for astronomers but what  about for the mariner,
    who requires a slightly different version?"
    It's  all done. Apart from the delta-T issue, I could print for you today the
    Nautical  Almanac for the year 2106, and it would be accurate to the nearest
    arcsecond.  The numerical integrations are just that good. We could even print
    it today with  simple instructions for determining delta-T at home with rules
    for applying that  correction to the data as printed in 2006.
    Anyone wanna buy the Nautical  Almanac for 2106 today? Cause I'll sell you
    one... for the right  price...
    42.0N 87.7W, or 41.4N  72.1W.

    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