Syllabus

In this, the Department of Physics and Astronomy’s eleventh “Celestial Navigation” Interterm offering, we will study the history, theory, and technique of celestial navigation. Nathaniel Bowditch’s continuously updated two-century-old volume “The American Practical Navigator” will be our primary reference.

Schedule details: Our first class meets in Merrill 4 in the Merrill Science Center on Tuesday, January 3rd from 1230 - 1430 continuing through Tuesday, January 10th (no class on Sunday). One coastwise daylong field trip (scheduled around weather conditions) is planned sometime during the above dates. A modest lunch will be provided.

Textbooks and Course Materials:

Bowditch, “The American Practical Navigator”     Science Library

The Nautical Almanac                                             Available for Use             

NOAA Training Chart / Block Island Sound          Available for Use

Parallel Rulers                                                         Available for Use          

Dividers                                                                   Available for Use

HO 229 - Sight Reduction Table                         Available for Use

HO 2102 D - Starfinder                                       Available for Use                                   

Sextants                                                   Provided by the Department                        

                                      Course Outline:

1st Lecture    - Bowditch / History of Celestial and Oceanic Navigation

2nd Lecture    - Celestial Concepts / the Sextant

3rd Lecture    - Nautical Almanac

4th Lecture   - Noon Sight / HO 229 Sight Reduction Table / Sun Lines

5th Lecture    - Use of the Star finder and the 57 Navigational Stars

Full Day Field Trip: Sextant Observations, Avery Point, CT

Full Day Field Trip: Shipboard Sextant Observations (Block Island Ferry)

Lecture One:  BOWDITCH / THE HISTORY OF CELESTIAL AND OCEANIC NAVIGATION

Nathaniel Bowditch; 1773 - 1838 Salem, Massachusetts - Two century history of “The American Practical Navigator” and profound significance of the volume - Importance of his revised sailing tables - Navigation in the Eighteenth Century - The Industrial Revolution and the clipper ship

Introduction to celestial navigation - The universe and solar system - The disparate celestial perspectives of the astronomer and the navigator - Heliocentric theory - Geocentric theory - Galileo - Ptolemy - Establishment of the Greenwich meridian

Time and the historical difficulty therewith - John Harrison and his invention of the first accurate shipboard chronometer - The magnetic compass: a lengthy and unclear history

Matthew Fountain Maury and the creation of worldwide pilot charts 

Introduction to Oceanic Navigation

True and magnetic compass headings - Correcting for deviation and variation - Isogonic lines - Course made good (CMG) - Speed made good (SMG) - Dead reckoning (DR) - Mercator projection - Rhumbline navigation and the loxodrome - Gnomonic chart projection and great circle sailing simplified - Explanation of hydrographic and geographic details of nautical chart used for this class - Use of parallel rulers and plotting technique - The plotting sheet; demonstration and uses thereof - DR exercises plotting routes of Block Island ferry for pending field trip

Lecture Two:  CELESTIAL CONCEPTS

The celestial sphere with the earth as the perceived center of the universe - Geodesy - Declination - Circle of equal altitude - The equinoxes and solstices - Zone descriptions - Greenwich hour angle (GHA) - Local hour angle (LHA) - Stars and the first point of Aries - Sidereal hour angle (SHA)

THE SEXTANT: ITS PRINCIPLES, CARE, AND USE

Correcting for instrument errors - Selecting the proper filters for ambient lighting conditions - Focusing technique

Outdoor practice (at ‘Merrill Beach’) measuring the subtended angle between the sun and the Holyoke Range to our south

 Lecture Three:  THE NAUTICAL ALMANAC 

Layout of the volume and its application for sun lines, Polaris, and the 57 navigational stars - Conversion of arc to time - Computing meridian passage, sunrise, sunset, civil, and nautical twilights - Extraction procedure for GHA and declination - Altitude correction table procedures - Extraction of the first point of Aries  

Lecture Four:  LATITUDE BY NOON SIGHT (LAN) AND POLARIS

Subtracting Ho from zenith to obtain ZD - Adding ZD and declination algebraically for the determination of latitude

Polaris and the first point of Aries - Use of the primary correction and the three secondary ‘A’ corrections for the determination of latitude

Exercises computing latitude from LAN and Polaris

HO 229 SIGHT REDUCTION TABLE

Selecting an assumed position (AP) and finding that position’s local hour angle (LHA) - Computing altitude and azimuth for the assumed position (AP) - Comparing computed (Hc) and observed (Ho) altitudes - Plotting the line of position (LOP) - Techniques learned in previous classes integrated with chart work - Plotting and advancing AM and PM sun lines Correcting compass for deviation and variation - Review of the “Coast Pilot” (provided) for information relevant to Avery Point and our Block Island crossing

 Lecture Five:  USE OF THE STARFINDER: THE 57 NAVIGATIONAL STARS  

Choosing the proper side of the starfinder - Template selection - Determination of the LHA of Aries and technique for aligning celestial meridian - Selection of stars that will provide a ‘good cross’ - Stars to avoid - The elusive ‘pinwheel’ - Practice performing star sight reductions until fifteen minute (per star) reductions can be accurately completed 

FIRST FIELD TRIP:  Land-based sextant observations (with our new professional quality sextants) to a visible nautical horizon will be taken at the University of Connecticut, Avery Point campus. A PM sun will be crossed with an LAN to fix our (known) position. We will also determine our hand-held compass error in preparation for our shipboard observations. This field trip is visibility dependent, and will be scheduled to take advantage of clement weather.

SECOND FIELD TRIP:  Much of what has been learned will be practiced on the open sea enroute to Block Island via the ferry. We will shoot an AM sun and advance it to a subsequent LAN observation. Predicated upon that information, we will DR our CMG, SMG, and ETA at Block Island. This field trip will also be scheduled for the wx.

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Captain Henry Parker Hirschel, the instructor for this course, practiced the art and science of celestial navigation while sailing as third mate aboard the Research Vessel Knorr and second mate aboard the Research Vessel Oceanus for the Woods Hole Oceanographic Institution.