Why Celestial Navigation

What do James Cook, Joshua Slocum, Bernard Moitessier, Robin Knox-Johnston and Tania Aebi have in Common? They knew how to use a sextant. So can you. Join this exclusive club.

There’s no GPS in space. We rely totally on GPS and similar satellite navigational systems such as Glonass, Galileo and Beidu. Unfortunately a large solar X flare or space disturbance could take out enough satellites to make the system unusable. Celestial Navigation has been around for centuries and is as reliable as the Sun, Moon, Planets and Stars.

Learn Celestial Navigation from very first principles

Understand the spherical geometry of space

Learn how to use an Open Source Math program to solve problems with simple trigonometric algorithms

Learn sight reduction using a variety of techniques such as the Nautical Almanac NAO and HO.249/AP3270

You will always know where you are and where you are going.

Course Description

Celestial Navigation Basics teaches you how to determine your position anywhere on the planet using simple spherical trigonometry. All examples feature sample Open Source Math code and manual sight reductions such as The Nautical Almanac NAO, and HO.249/AP3270. The many benefits are:

Be confident that you will know where you are if your electronics fail

Simple paper methods requiring only charts, Nautical Almanac/AP3270, pencil, forms, geometry set

Learn the Spherical Geometry of Earth & Space

Follow in the footsteps of great navigators like James Cook, Joshua Slocum, Sir Robin Knox-Johnston and Bernard Moitessier

Increased situational awareness, not always staring at a digital display, but observing all the natural occurrences around you


High School/College Geometry & Trigonometry minimum

Laptop with Open Source Scilab 6.1.x or ScicosLab 4.4.2

Entry programming knowledge. Basic, or C, or Java, or Fortran or Similar

Access to sextant (Inexpensive kits available)

Course Curriculum

Chapter 1 - Introduction

Introduction & brief history of Celestial Navigation and why it's very important

Download & Installation of Math Software, Almanacs & Sight Reduction Tables

Quiz, Homework Exercises

Chapter 2 - Spherical Triangle

Spherical Law of Sines, Cosines, Napier's Analogies, Haversines

Great Circle Distance & Bearings

Navigational Triangle

Solved Triangle Examples

Quiz, Homework Exercises

Chapter 3 - Spherical Triangle on Celestial Sphere

Available Week July 26th

Celestial Sphere & Horizon Diagram

Observer & Celestial Body GP 

Coordinates: Lat, Long, GHA, Dec, LHA, N, S, Azimuth, Zenith

Solved Triangle Examples

Quiz, Homework Exercises

Chapter 4 - Nautical Sextant

Available Week Aug 2nd

Sextant Variants

Sextant Altitude Measurement

Sextant Dip Angle

Sextant Refraction

Sextant Parallax

Sextant Semi Diameter

Sextant Sight Reduction 

Solved Reduction Examples

Quiz, Homework Exercises

Chapter 5 - Position Determination

Available Aug 9th


Position by North or South Celestial Pole

Position by Meridian Passage of Sun

Position by Altitude & Azimuth

Circle of Position & Sumner Line of Position

Position by Marcq St. Hilaire - Intercept Method

Position by Altitude of Two Celestial Bodies Direct Solution

Solved Position Examples

Quiz, Homework Exercises

Chapter 6 - Nav Publications  & Software

Available Aug 16th

Bowditch American Practical Navigator

Nautical Almanac

Sight Reduction Procedures

Nautical Almanac NAO Sight Reduction Procedure 

Pub. 249/NP303/AP3270 Sight Reduction Procedure 

Pub. 229 Sight Reduction Procedure

Google Earth

Admiralty UKHO NavPac and Compact Data DP330 2016-2020

Navigational Algorithms

OpenCPN & Celestial Navigation Plug In

Solved Examples

Quiz, Homework Exercises

Chapter 7 - Sight Reductions

Available Aug 23rd

Sight Reductions Nautical Almanac NAO method

Sight Reduction Pub.249/NP303/AP3270

Solved Reduction Examples

Quiz, Homework Exercises

Chapter 8 - Conclusions

Available Aug 30th

Latest developments in CelNav

What's next

Appendix A

ScicosLab/Scilab Open Source Math Software

Appendix B

Basic Navigational Data



Instructor Bio

Jeremy Clark is a Senior Telecommunications Engineer. He worked in the Canadian telecom industry for 21 years as a wireless transmission engineer and later was a professor for 16 years teaching engineering telecommunications technology courses. For the past 10 years he has written EBooks and developed courses in Telecommunications and Celestial Navigation. He has worked and travelled in Canada, Europe, Africa, South East Asia and Central & South America.

Grab your sextant right now!