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
    Change of assumed position terminology
    From: David C
    Date: 2020 Apr 24, 18:56 -0700

    While reducing and plotting some sights I became confused. The results did not always make sense.  On reflection I decided that a change in terminology was needed.  I always take my sights from the same location and I have a gnss receiver. Hence the concept of a DR position is meaningless. Additionally I work sights by methods that have differing requirements for assumed longitude. I have therefore abandoned the use of the terms  "DR position"  and "assumed position" and now use three positions:

    GNSS position.  Used with the cos and haversine methods. This is the method used for checking a sextant reading.

    Assumed_t.  Longitude selected  to make the hour angle (t) a whole degree.   Latitude a whole degree.   Used with 249 and most short methods. Can also use the cos and hav methods.

                     An exception is the Aquino method. The table lookup begins with t a whole degree. It is not necessary to calcuate the corresponding longitude.

                     The  Aquino table provides an assumed longitude (for which t is not a whole degree).

    Assumed_p.  Lat and long  selected to make plotting easier - typically whole degrees. Used with the cos and laversine methods.

                    As an example I am at long 175° 05.2'. An obvious value for long_p is 175°.

       
    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