Lunar Distance and Age of Sail Classes:
Fascinating classes taught by a fascinating and capable instructor.
Lunars class is challenging and fun. Frank presents several different recipes for accomplishing lunars, one of which seems almost easy (kind of). Highly recommended for anyone interested in celestial navigation or nautical navigation history.
Jeffrey Rock
FAA Designated Pilot Examiner
About me, Frank Reed
I'm an astrophysicist by education. I make maps and apps for a living. As one of the world's leading experts in celestial navigation, I create and teach workshops in historical and modern practice, science, and mathematical theory of celestial navigation and nautical astronomy. I'm also an experienced public speaker, available for presentations and events on astronomy, celestial navigation, and other topics.
I create and teach all of the workshops in celestial navigation presently offered by ReedNavigation.com, including all online workshops. I also taught all of the in-person classes offered at the Treworgy Planetarium at Mystic Seaport Museum from 2010 to 2025 [Mystic Seaport workshops on hiatus as of 11 Nov 2025]. I am fluent in nearly every technique and tool in celestial navigation from ancient historical methods to the most modern computer-based applications, and I am the world's leading expert in the topic of lunars --the process of determining absolute time at sea by measuring with a sextant the angular distance between the Moon and the Sun or a star.
General Background:
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Endurance22 Celestial Navigation Expert
In 2021-22, I was hired as an astronomical and celestial navigation expert for Endurance22, the expedition that found the wreck of Ernest Shackleton's exploration ship Endurance deep under the ice of the Weddell Sea off the coast of Antarctica. This was a pandemic-erahave remote project; I did not get to play with the penguins! My contribution was highlighted in the January 2025 issue of National Geographic magazine.
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StarTalk television: Celestial Navigation Expert
I was recently a guest, aboard as an expert in celestial navigation, on an hour-long episode of StarTalk, a science talk-show hosted by Neil deGrasse Tyson available on various streaming services (look for S4 E10). Dava Sobel, author of "Longitude" also joined us in the studio for one segment. Also available as audio-only (free).
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Developer, GPS Anti Spoof apps for Android and iOS
My "GPS Anti Spoof" app has been released for iOS and Android. The app does everything. Shoot the Sun (or Moon, planet, star) with your sextant and directly compare with the displayed altitude in the app. No calculations / no paperwork. It's great for sextant training --you get instant feedback. And it easily detects GPS spoofing, if you're worried about pirates and that sort of thing! Unlike nearly all other available apps and software, this app also incorporates the deflection of the vertical, which can throw off your sights by more than one minute of arc near many islands. The app is dead-on accurate. Details and download links: ReedNavigation.com/GPSantiSpoof/. -
Head Cartographer, Centennia Historical Atlas
The principal focus of my business, Clockwork Mapping, is the development and marketing of the Centennia Historical Atlas. The Centennia Atlas was, for over fifteen years, required course material for all students at the US Naval Academy at Annapolis, MD. Please visit HistoricalAtlas.com to learn more. My youtube channel has over 1.2 million views. Other videos, generally copyright-violating, based on my map animations have accumulated over fifteen million hits. -
Invited Whaleship Voyager
Celestial navigation expert on the 38th Voyage of Mystic Seaport's 1841 whaleship Charles W. Morgan, July 2014. Demonstrated historical celestial navigation techniques at sea off the coast of Massachusetts. Organized and operated 38Talk, an online community for discussions among Voyagers and others related to the 38th Voyage. Featured guest in live webcast from the deck of the Charles W. Morgan as we sailed among the whales on Stellwagen Bank north of Cape Cod, July 2014. I discussed the basics of "nautical astronomy" for an introductory audience: watch the video. I also appeared briefly on the CBS Evening News in their coverage of the 38th Voyage. -
Gravitation and Physics
I am an expert in gravitational physics including topics ranging from theoretical general relativity to practical tidal analysis. My thesis at Wesleyan University (Middletown, CT, 1984) was awarded High Honors, and I was also the winner of the Sherman Prize in Mathematics and the Bertman Prize in Physics. Read an article about me from Physics World magazine in their Once a Physicist column. -
Leap Second Conference
In October 2011, I presented a paper on celestial navigation and the issue of "leap seconds" at the conference on "Decoupling Civil Timekeeping from Earth Rotation" hosted at the headquarters of AGI near Philadelphia. I was the "small fry" non-academic among the world's experts in positional astronomy and the science of time-keeping including Dennis McCarthy, George Kaplan, and P. Kenneth Seidelmann among others. Neil deGrasse Tyson, television personality, host of the new Cosmos, and director of the Hayden Planetarium in New York City, also joined us as an interested guest. Here's a photo of us. -
StarTalk Radio
In addition to appearing recently on StarTalk television, I was a guest on Neil deGrasse Tyson's StarTalkRadio in 2012: StarTalkRadio: Time Lords and the Science of Keeping Time (to listen to my contributions, go to time stamps 12:09-14:50 and 24:20-25:35). Here's a gallery of the participants. -
Published article "Celestial Navigation and UTC"
On the significance of changes in 'leap second' procedures and its potential impact on traditional celestial navigation. Presented at conference in Exton, PA. October, 2011. Published in the Journal of the American Astronautical Society, 2012. Read the preprint. -
Interview on NPR's "Here and Now"
Discussing the future of celestial navigation and the recent announcement that some basic instruction in celestial navigation will once again be part of the curriculum at the US Naval Academy. October 2015. Listen at WBUR here or on ReedNavigation here. -
"After Longitude", National Maritime Museum
In March 2012, I delivered two presentations on lunars at the "After Longitude" conference at the National Maritime Museum at Greenwich, UK (a few hundred yards from the Prime Meridian). One paper focused on the role of lunars in American commercial dominance in the Pacific in the 19th century, especially aboard whaling vessels. The second paper "Lunars in the Space Age" focused on modern use of lunars for position-finding in space. Lunars were shot during Apollo missions to the Moon, especially on the flight of Apollo 8, the first manned mission to reach lunar orbit. -
Navigation Conferences
I have organized "Navigation Weekend" conferences in 2006, 2008, 2010 and 2017 bringing together navigation enthusiasts, scholars in the history of astronomy, and practical navigators to the Treworgy Planetarium at Mystic Seaport. I also did numerous presentations of my own at these conferences on lunars, the history of the Nautical Almanac, and other topics. -
Management of NavList
I manage NavList, a community devoted to the history, modern practice, and future of celestial navigation and other forms of traditional position-finding. NavList began as an online community and our message boards continue as, by far, the most active arena for online discussions on these topics. Note that our online discussions are now found at NavList.net. -
Navigation Instructor, Physics Instructor: Northeast Maritime
I've recently taught several intensive two-week USCG licensing classes in celestial navigation at Northeast Maritime Institute in Fairhaven, Massachusetts. I am a USCG-approved instructor in celestial navigation. I also taught an introductory college level conceptual physics course at NMI during the Winter/Spring term of 2017. -
Editor, Pub.249 "Tables for Navigation"
I maintain the celestial navigation tables known as "publication 249, vol.1, Selected Stars", marketed commercially by Celestaire, Inc., which are used by thousands of vessels at sea as a backup method of celestial navigation. These tables list the altitudes and azimuths of stars during twilight enabling quick and easy sight reduction. The tables in volume 1 are updated every five years. I manage the complete update process including collecting data from official USNO sources and validating that data by independent calculation of each of over 400,000 numbers, and I also produce and edit the pdf from which the printed book is published.
Comments:
Jeffrey Rock wrote: 8👍
John Brown wrote: 6👍
Frank
Thanks for a great app. The new option of using SI unit is really useful for us on the other side of the pond.
I have upgraded to the pro version and passed news of the upgrade to a friend learning to use her sextant. No doubt she will also relay this info.
Best regards
John Brown
Thanks for a great app. The new option of using SI unit is really useful for us on the other side of the pond.
I have upgraded to the pro version and passed news of the upgrade to a friend learning to use her sextant. No doubt she will also relay this info.
Best regards
John Brown
Homer Smith wrote: 10👍
Over the past few years I have taken all of the Celestial Navigation courses taught by Frank Reed at ReedNavigation.com and I recently repeated Modern CN 1 & 2 just for the pure enjoyment that it brought to me.
My interest in CN started a few years ago as I puzzled over how the stars could be used to find one’s position on the earth. I tried to learn CN through self-study, but I couldn’t make the subject matter interesting and realized that this was not the correct approach. You need a skilled instructor that can guide you through the learning process, and that’s what Frank Reed provides.
In a relatively short period of time I had a solid grounding in CN. Frank has unmatched knowledge of CN. His classes are fun, interesting, and sprinkled with historical context and include as much or as little math as you desire. His visual aids were very helpful and the time spent on discussing how to properly use a sextant to take a sight was beneficial. You will learn how to find stars in the night sky by which to navigate. The downloaded course guide is very concise and includes tables that are valid for 5 years into the future.
You don’t need to be at sea to do CN. I live inland and learned in the class how to do land-based navigation with a sextant, either with a large or small body of water to provide a true horizon, or with no water horizon at all.
Going back 250 years, I understand how CN was practiced through the ages, up to the present time with calculator, equations and tables. Thanks to Frank, I take great satisfaction in knowing that I possess a skill that very few people have. I highly recommend his courses.
Homer R. Smith M.D.
My interest in CN started a few years ago as I puzzled over how the stars could be used to find one’s position on the earth. I tried to learn CN through self-study, but I couldn’t make the subject matter interesting and realized that this was not the correct approach. You need a skilled instructor that can guide you through the learning process, and that’s what Frank Reed provides.
In a relatively short period of time I had a solid grounding in CN. Frank has unmatched knowledge of CN. His classes are fun, interesting, and sprinkled with historical context and include as much or as little math as you desire. His visual aids were very helpful and the time spent on discussing how to properly use a sextant to take a sight was beneficial. You will learn how to find stars in the night sky by which to navigate. The downloaded course guide is very concise and includes tables that are valid for 5 years into the future.
You don’t need to be at sea to do CN. I live inland and learned in the class how to do land-based navigation with a sextant, either with a large or small body of water to provide a true horizon, or with no water horizon at all.
Going back 250 years, I understand how CN was practiced through the ages, up to the present time with calculator, equations and tables. Thanks to Frank, I take great satisfaction in knowing that I possess a skill that very few people have. I highly recommend his courses.
Homer R. Smith M.D.
