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: Landmark sights
    From: Peter Monta
    Date: 2019 Aug 6, 18:45 -0700
    Hi Lars,


    My answer (although not double checked): azimuth = 246.3° ; elevation = 1°28'


     Yes, that's what I get too---azimuth 246.258 degrees, elevation 1.461 degrees.  Or in sexagesimal, azimuth 246d 15.5', elevation 1d 27.6'.  The residuals are around 0.2 arcmin rms.  Maybe an uncertainty of 0.5 arcmin is justified considering timing error and sextant errors.  A third star would have inspired more confidence.

    This is the apparent position of the streetlamp under those weather conditions, so using it at other temperatures and pressures in the air path would need a small correction.

    Come to think of it, they say atmospheric refraction is extremely small in azimuth, maybe on the order of 10 mas, if I remember right, for non-pathological situations on reasonably flat land.  So some sort of aziumth-only landmark navigation ought to be possible.  More landmarks would be needed, since each one is good for only one degree of freedom.  The elevations of the landmarks would still need to be known to moderate accuracy, but with the right geometry, the high precision would come mostly from the azimuths.  From a terrestrial point of view, this is ordinary horizontal surveying, but then adding some near-horizontal ties to stars.

    Cheers,
    Peter

       
    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