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
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-era 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. -
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:
John Brown wrote: 6👍
Jeffrey Rock wrote: 8👍
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
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
Mark Coady wrote: 11👍
I have now done every course I think that has been offered so far at Mystic Seaport taught by Frank Reed in the last two years. I found the courses to all be extremely rewarding.
Several things stand out. The course material is presented in a balanced way, with a well thought mixture of detailed calculation, broken up by historical, factual, and hands-on aspects. This type of teaching is well suited to most, as it provides periods of more intense reasoning with relaxation and humor. Anyone can walk away with new-found knowledge. I also feel that the approach of understanding historical context and a simple practical approach is unique. It has gone a great way toward clearing up a lot of my preconceived ideas and confusions resulting from the many contradictory or esoteric approaches found in various volumes or on the internet.
Very simply, I learned a lot and it went a long way toward clearing up a mess. I was fascinated the whole time. The courses and NavList provide the tools to keep learning even after the course is over. I left able to measure what I see with a more calibrated eye for real world application, and a greater appreciation of human history. I can strongly recommend these classes for the curious, the fascinated, the historian, the hardcore navigator, or the armchair one. There is something in them for all.
I also found the NavList community to be helpful and encouraging as my journey continues. I hope I can undertake even more material in additional courses in the future.
"There is nothing - absolutely nothing - half so much worth doing as simply messing about in boats" (Kenneth Grahame, from the "Wind in the Willows")
Capt. Mark
Several things stand out. The course material is presented in a balanced way, with a well thought mixture of detailed calculation, broken up by historical, factual, and hands-on aspects. This type of teaching is well suited to most, as it provides periods of more intense reasoning with relaxation and humor. Anyone can walk away with new-found knowledge. I also feel that the approach of understanding historical context and a simple practical approach is unique. It has gone a great way toward clearing up a lot of my preconceived ideas and confusions resulting from the many contradictory or esoteric approaches found in various volumes or on the internet.
Very simply, I learned a lot and it went a long way toward clearing up a mess. I was fascinated the whole time. The courses and NavList provide the tools to keep learning even after the course is over. I left able to measure what I see with a more calibrated eye for real world application, and a greater appreciation of human history. I can strongly recommend these classes for the curious, the fascinated, the historian, the hardcore navigator, or the armchair one. There is something in them for all.
I also found the NavList community to be helpful and encouraging as my journey continues. I hope I can undertake even more material in additional courses in the future.
"There is nothing - absolutely nothing - half so much worth doing as simply messing about in boats" (Kenneth Grahame, from the "Wind in the Willows")
Capt. Mark
