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: Latitude and longitude around noon
    From: Frank Reed
    Date: 2017 Mar 30, 09:30 -0700

    Brad Morris, you wrote:
    "As a hint to the others, have you checked your answer on Google Earth? Does your positional solution afford a natural sea horizon view due south? If not, you need to rethink your answer."

    That answers a separate question. We can reasonably ask, and often do ask, what is the best celestial fix from the data on-hand, and then separately we ask, what is the best fix based on all available information including clever detective work (also sometimes known as "cheating" *). In the latter category, when faced with a recent digital photo of a celestial phenomenon, a number of people have pointed out that we can use the GPS tag data in the photo to confirm the position. True! But only relevant if the exact position is the actual goal of the discussion. 

    In an earlier message, after comparing the analyses up to that point, you wrote:
    "Proving, yet one more time, that obtaining longitude from the noon latitude observation is fairly worthless."

    You may have missed the boat on this one, Brad, by retreating to the barricades of textbook orthodoxy :). One can indeed get a very good celestial fix from sights around noon by a variety of methods, but you have to do it "right". You need a method for determining the axis of symmetry of the sights that manages statistical noise, and you need a method for pulling the peak altitude from a parabola-like curve, and you need a method for dealing with the changes in the curve that result from motion towards or away from the Sun. Most of the orthodox complaints over this methodology have simply assumed the lowest common denominator approach of "drawing a curve by eyeball" is the only one worth considering. It's a standard that is guaranteed to confirm the bias of a priori belief. By applying simple, proper methods, one can get both an excellent latitude and a "good" longitude from sights of the Sun around local noon. The orthodoxy is wrong.

    Frank Reed

    * I mentioned detective work as "cheating". Speaking of detectives, last night I was watching an episode of "Columbo" from 45 years ago. There is a scene at LAX (airport) about meeting a charter flight from Mexico, and some stock footage shows a plane landing with a great view from beneath the fuselage where we see the landing gear coming down. The landing gear pairs emerge from the fuselage itself from behind big triangular doors. I just happened to look at the screen at that moment and laughed because that clearly was not the sort of plane that might be arranged for a charter flight. It was the unique landing gear configuration of a B-52 bomber. No big deal, of course, stock footage is used for filler frequently and was especially common in tv production back then. But still... I wanted to see where this came from --it was a nice view! So I popped online and started looking for video of B-52 landing gear. I found a number of similar cases but no match. Then it dawned on me: you have to use the Internet the "right way", and in this case, the right way is to assume that someone else has already asked and answered the same question (and with any luck they have answered correctly!). So rather than searching for video of B-52 landing gear coming down, I searched for "B-52 in an episode of Columbo". And of course that worked. I now "know" what movie that footage was taken from.... But it's cheating. I don't really know anything except someone else's best guess until I confirm it myself. At least my curiosity was sated :).

       
    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