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: Classic Trig Log Sight Reduction Revisited
    From: Greg Rudzinski
    Date: 2014 May 29, 19:30 -0700

    Nicely done Noell ! Thanks for posting.

    Greg Rudzinski

    Re: Classic Trig Log Sight Reduction Revisited
    From: Noell Wilson
    Date: 2014 May 29, 06:51 -0700
    This inspired me to finish my "multiple ways to do sight reduction" in Excel. That said, I failed in getting Excel to recognize all the terms and to write everything so each step could be followed. The final result is a mix of Excel, longhand, slide rule, and calculator.

    I started this to illustrate how we ended up expressing negative logs as 9.xxx-10 but I ended up not answering that question. Someone smarter than me, and without a calculator, figured that the logCos of 42.175 Deg is -0.13012 and expressed that as 9.869875 -10. It's easy with a calculator but daunting without.

    Anyway, the attached is for a different problem, from an Ageton example, with:
    Lat 42_10_30
    Dec 23_06_24
    t 61_33_42 and an answer in Ageton of Hc = 36_01.5 and Az = 90.

    In the attached:
    First is the input, formula, and answer. Angles as decimal degrees for Slide Rule.
    Second is the result with a 10" plastic slide rule similar to a Deitzgen 1733. I was raised with a slide rule and I usually get surprisingly good results if the angles are mid-range.

    Third is Cos and Sin as decimals multiplied by calculator with my longhand result in a separate box to the right.

    Finally, a calculator used to get logs as negative numbers and making the calculation using those negative numbers. The calculations are repeated to the right in the standard 9.xxx -10 format of the Trig tables.
    Regards, Noell
    ----------------------------------------------------------------
    NavList message boards and member settings: www.fer3.com/NavList
    Members may optionally receive posts by email.
    To cancel email delivery, send a message to NoMail[at]fer3.com
    ----------------------------------------------------------------

    Attached File:
    Click to enlarge.
    ----------------------------------------------------------------
    NavList message boards and member settings: www.fer3.com/NavList
    Members may optionally receive posts by email.
    To cancel email delivery, send a message to NoMail[at]fer3.com
    ----------------------------------------------------------------

       
    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