Classes in celestial navigation and related topics

A vernier sextant Chronometer Navigation tables Noon Sun and time sights Shooting lunars Two-body fix Lunars Lunars Geometry Sextant Micrometer

Celestial Navigation Classes: Fall 2016

Classes at Mystic Seaport in Mystic, Connecticut and also at Eastern Connecticut State University in Windham, Connecticut (details on ECSU classes coming soon).
A frequently asked question:"They both sound good - which class should I take?"

Of the two introductory classes above, if you're interested in history, old logbooks, and perhaps a bit more interested in mathematical details, too, then sign up for the "19th century methods" class. If you're more practically oriented, more pragmatic, not much interested in historical details, and mostly looking for a good (last resort) backup for your GPS, then sign up for the "modern celestial" class. Both will give you real, usable navigational skills and methods.


28 posted. 4 waiting approval.

Todd Smith wrote: 12/12/2009
Hello Frank,
Do you offer celestial nav courses for sailors?
Frank Reed wrote: 12/15/2009
Yes! Weekend classes this Spring at Mystic Seaport. You can read about them here or on the web page for planetarium courses at the Treworgy Planetarium at Mystic Seaport here: planetarium courses.
a visitor wrote: 5/27/2013
I'm very interested in celestial navigation. I've read a few chapters of an old copy of "Bowditch" from 1938. I think I understand most of it, but I'm hoping you can recommend some other books. Is there some place where I could find older nav techniques? Maybe circa 1865, Civil War era?

Frank Reed wrote: 5/27/2013
Yes, there are now many historical navigation works available on the Internet. You can download most of them as pdf's for convenient offline reading. I maintain a list of them on the NavList message boards: historical navigation resources. You should consider taking our "Celestial Navigation: 19th Century Methods" class. It's an introductory level weekend class where we learn the "Old Navigation" methods.

Frank Reed
Frank Reed wrote: 5/27/2013
I forgot to mention that the NavList message boards are a great place to discuss historical celestial navigation. Please do stop by!

Dr. Russell D. Sampson wrote: 6/22/2013
I took Frank's 19th Century Celestial Navigation class in April 2013 and really enjoyed it. Not only was the class interesting but my fellow classmates were too; a retired skipper of a ballistic missile sub, the son of the fellow who invented GPS, a teacher, a captain of a Panamax container ship and a fellow who crossed the Atlantic solo - twice!

The class was also a great resource for my teaching and my own research interests such as the visibility of celestial objects in the daytime (Jupiter and Venus) and the effects of astronomical refraction near the horizon. I hope to take more workshops with Frank.

Dr. Russell D. Sampson
Wickware Planetarium
Eastern Connecticut State University
Sarah Ilsley wrote: 6/22/2013
I also took Frank's 19th Century Celestial navigation class. The instruction was thorough and I learned much more than I expected. Not only the techniques of celestial navigation, but a rich account of it's history as well. We had plenty of time to practice using sextants ourselves, and Frank did his best to make sure that each of us understood what he was teaching. He really knows his stuff!!

Also, the class was made more enjoyable through discussions with my other classmates during, and after the class had ended! You know a class is worthwhile when the learning continues outside of the classroom.
Amy Reifsnyder wrote: 6/22/2013
Thoroughly enjoyed the Celestial Nav class at Mystic Seaport. Very clear instruction, with patience and broad depth of understanding for all in attendance.
I highly recommend any of Frank's classes and workshops, since the guy knows what he's talking about, and he can explain it to folks with (or without) all kinds of math and physics backgrounds.

Plus, it's just plain fun to realize that all you have to do to find out where you are in the universe is "look up". Now that's just cool.
Philip M. Sadler wrote: 6/22/2013
What a joyful and stimulating experience to enroll in Frank Reed's class, Celestial Navigation: 19th Century Methods. Frank is a skillful and engaging teacher, able to draw students into this fascinating subject, whether they be novice or experienced. His depth of knowledge is tremendous. Participants get a real taste of what it was like to be aboard a sailing ship of the day. I learned much to enliven my own teaching and decode 19th century ship's logs. It is a rare experience, indeed, to have so much thoughtfulness, enthusiasm, and fun packed into two days. This is the way to learn!

Philip M. Sadler, Ed.D.
F.W. Wright Senior Lecturer in Celestial Navigation
Harvard University Astronomy Department
Cambridge, MA
Samuel S. Caldwell MD wrote: 6/25/2013
I thoroughly enjoyed Frank's first class in celestial navigation held at Mystic Seaport, and hope to be back for more.

Samuel S. Caldwell MD
Saratoga Springs, NY
Andrew Seligman wrote: 9/16/2013
I took Franks basic class at Mystic seaport. Frank is a fantastic instructor. He made the noon-sight and polaris sight reduction really easy!
Paul Krantz wrote: 1/30/2014
I took Frank's Easy Introductory Celestial Navigation by Noon Sun course and was impressed with both his in-depth knowledge and practical skills in the use of a sextant as well as his awareness of a sextant's limitations along with its advantages as a modern navigational instrument.

I am the author of a new release book, "Riding the Wild Ocean," a collection of my wildest adventures in small boats under twenty feet in length from Cape Cod to the Dry Tortugas. Although my craft is too small and unstable a platform for practical use of a sextant, my extensive experience sailing small boats on the open water enabled me to recognize the great extent to which Frank Reed's instruction reflects the wisdom of a long experienced and master seaman. I can confidently recommend any of his courses based on my delightful experience with this skilled and engaging educator.

In case anyone is interested, my book will be available in bookstores and online (Amazon) after March 11, 2014 but can be purchased now directly from the publisher at:

Paul S. Krantz, Jr.
Dan Jablonski wrote: 11/4/2013
Is it possible to use the method of lunars without a stop watch and with no measurement of local time? And, will you be offering your lunars course again in the near future? Thanks,

Dan Jablonski
Johns Hopkins Applied Physics Lab
Laurel, MD
Jeff Dirgo wrote: 12/29/2013

Good Afternoon

I'm a write in NJ and I'm researching a novel and raised a question about nautical navigation. I understand that navigation almanacs are published annually. If a longitude and latitude were given for an island location that was taken in 1930 using a sextant, would there be an appreciable difference in the location were a character were to sail to those coordinates 75 years later? The island in my novel is not plotted on any map, but my character only has a position expressed in longitude and latitude as fund in an old ships log. I realize as much as one degree of latitude can be as much as 65 +/- miles off.

I imagine I'm asking if the celestial deviation or instrument accuracy would be great enough in those elapsed years to put a boat today an location that was indeed different in 1930, and if so by how far. My story is set in the central Indian Ocean.

I've read through the course offered at Mystic Seaport in March and wondered if this would be beneficial to my research.

Thank you so much for your time.

Jeff Dirgo
Bruno Herregods wrote: 3/15/2014
Im currently revising for my celestial exam. Im doing the RYA/MCA syllabus. I do have a good grasp on the subject but im in need of some question that I can practice on.
Would you be able to assist me.

Thank you

Bruno Herregods
Paul Perrotti wrote: 3/20/2014
Hi, Frank.

Is the Intermediate Celestial Navigation Course still being offered at Mystic Seaport? I'm registered for the introductory course later this month but I haven't seen the second class posted on their website.

Thanks, Paul
Patrick Smyth wrote: 6/5/2014
How were the first sight reduction tables produced? I can see the progress through sines and cosines, haversines, and intercept method, but believe the earliest tables of Hc and Az computations were produced just before WW2. Indeed, the approaching war may have hurried the project forward.

Quite apart from the computations, the type setting and printing must have been formidable! Were there mechanical computers that could handle this? How many people were involved?

Mystic looks a fun place to study astro nav - I am from Poole, on the south coast of England.

Regards, Patrick
Chris Moller wrote: 7/29/2014

I was very interested to see your course on lunars. I just learned about your class but have missed the dates. Will there be another class soon?

All the best,

Chris Moller
Charles McElhill wrote: 8/6/2014
Good morning. With regard to the remainder of 2014, I see that you are offering additional celestial classes at Mystic in October and November. Is this correct and are you offering Lunars again in November. Thanks for your time. Have a great day.
Frank Reed wrote: 8/6/2014
Chris and Charles, Yes. We are offering a LUNARS class again this November! Details above.
David Pike wrote: 8/24/2014
Hello Frank

I listened to you at Greenwich in 2012. I'd like to try a Lunar. My experience has been only in the air with a MkIX bubble sextant (as a young man) and later with a Smiths Mk2B periscopic sextant, both of which I have working examples of. I also have a Hughes Mate's marine sextant with relatively small mirrors which I bought and a plywood and bathroom mirror-tile version which I made. I scratched the plastic arc with a dividing gear on a lathe. The verniers scratched on the arm. It gives about 3nm on still nights shooting off a washing up bowl of water and dividing the Hs by two. My problem is I live inland in a built up area. Will it be OK to use the Hughes or my home made nautical sextant to measure the lunar distance and the altitudes using the Smiths pendulous reference periscopic sextant accurate to about 2 minutes of arc for the altitudes?

I suppose what I'm saying is is it only the lunar distance which needs to be measured to tenths of a minute, or do the altitudes have to be measured equally accurately?


Frank Reed wrote: 8/25/2014
David, Absolutely. The altitude accuracy requirement is rather low (+/-5' in most cases and often much less). In fact, if the lunar distance arc itself is near 90 degrees, the altitude of the Moon can be just a rough approximation, plus or minus a whole degree is no problem. The altitude of the other body should still be accurate to +/- 5' usually. Also note that if the altitude of the other body is also going to be used to determine local apparent time, then it should be measured as accurately as possible.
Bob Goethe wrote: 9/11/2014
We are considering using the planetarium in Edmonton as a place to teach celestial navigation, enjoying freedom from cloudy skies by actually teaching the mechanics of sextant use inside the planetarium theater itself.

I would appreciate talking to your people if you have done this, to discuss things like determining "dip" in a theater where the sextant user is actually BELOW the projected horizon rather than above a true horizon outside.

Another issue is that the altitude of a celestial object projected on the theater's dome would vary from one seat to another inside the theater. I would love to discuss how you have managed this.

Bob Goethe
Frank Reed wrote: 9/11/2014
Bob, while many aspects of celestial navigation and positional astronomy can be taught under the dome, taking sights with a sextant in a planetarium is a fantasy --a fantasy often rediscovered! The problem of "dome parallax" (the variation of altitudes from one location to another under the dome, which you mentioned) is insurmountable with a "normal" planetarium projection. Even something as simple as estimating the altitude of the north star by "fists" is hopeless.
Andrew Lilly wrote: 10/1/2014
Frank and Bob,

You both bring up a fantastic idea that has been approached and (to some extent) solved before. Specifically for the U.S. lunar space program at the Morehead planetarium in NC.


Frank: you excellently bring up dome parallax, but isn't there going to be at least one point, or small area (near center of dome sphere, focal point of the dome) where the parallax wouldn't be nearly as significant? I'd assume this may require a platform / scissor lift etc and might not always be practical, dependent on the type of star projection system in the planetarium selected. I'd also guess the use of a bubble horizon would be necessary too.

Like Bob, I am also very interested in this subject with a local planetarium interested in the subject, and it doesn't seem to have a well published solution ;)

Your collective thoughts? Are there any good resources available on the subject?


Frank Reed wrote: 10/5/2014
Andrew, even if you shoot sextant sights from the very center of the dome, the results are poor due to parallax. Work out what happens in a dome with a 30 foot radius, if you shift the location of the sextant by just two inches. You should find that a "star" at 45 degrees altitude shifts by more than 13 minutes of arc. For all but the most crude observations of altitudes, this is too much to be useful for any purposes. Planetariums are very helpful for teaching coordinate systems and motions of the stars, and of course they're great for teaching basic constellations. But they do not function as "virtual reality" projections of the sky --at least not of sufficient fidelity for practicing celestial navigation sights in any useful way that I have been able to discover.
Barry Cousineau wrote: 1/22/2015
Hi Frank
I plan on signing up for the Modern Celestial Navigation Course offered in March and possibly the intermediate course as well. Is it recommended to purchase a sextant prior to the course, if so where would one purchase this instrument?

Barry Cousineau
Frank Reed wrote: 1/24/2015
You don't need to purchase a sextant in advance, but if you have one, yes, bring it along. If you would like to acquire a relatively inexpensive, functional sextant, I would suggest looking for a lightly-used Davis plastic sextant. These turn up fairly often on eBay for $100 or less. They're real sextants. You can cross an ocean with one. They're somewhat less accurate than a proper metal instrument, but it's not a major concern. And you can always upgrade later.

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