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: Height by sextant angle
    From: Frank Reed
    Date: 2014 Dec 12, 12:25 -0800

    Yesterday I posted this image of the shadow of a "zeppelin" over London. I could not identify the buildings at the time, but as I looked at the photo again this afternoon, it dawned on me that the setting looked familiar. I walked by that fountain just two years ago! The airship is flying over Greenwich. These buildings are the Old Royal Naval College, currently occupied by the University of Greenwich. I would say that at the time of the photograph the airship was passing almost directly over the main hall of the National Maritime Museum. A nice coincidence for a NavList message. The longitude of the airship was less than a minute of arc west of the prime meridian... Based on the shadow locations and assuming the date is July 10, I estimate that it's between 10:45 and 11:00 am.

    So has anyone else determined the airship's altitude yet? I get roughly 800 feet for the slant height which would imply about 700 feet for the vertical altitude. It all depends on the angular diameter of the Sun which is what determines the width of the "fuzzy edge" or penumbra of the airship's shadow...


    Frank Reed
    Conanicut Island USA

       
    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