In the latest NAWCC Bulletin, there is a nicely written article about Mike Bovarnick of Seattle and the first cesium clock, the Atomichron. https://www.nawcc.org/wp-content/uploads/2024/03/Bulletin-MarApr24-468-webopt.pdf See pages 132-134, pdf pages 22-24 Gary

Some related information... Only a few Atomichron are left. The Smithsonian has one or two. There's one on display at the NAWCC museum in Columbia, PA, as mentioned in the article. A private collector in Pittsburgh, PA has one. And I have one. That find was the result of decades of searching, some luck, and a 2600 mile road trip to pick up the monster from a dusty garage in Minnesota. Photos of that encounter are here (not in working condition): http://leapsecond.com/museum/nc2001/ The Atomichron got some press from a recent talk I gave, see page 19: http://leapsecond.com/ptti2020/2020-PTTI-tvb-Atomic-Timekeeping-Hobby.pdf In that photo most of the electronics was removed so the massive cesium beam tube is visible in its entirety. The anonymous arms on the right are holding a modern cesium beam tube for comparison. A reporter at the conference wrote a nice bit about it [1]. --- There are several papers about the Atomichron and early cesium clocks: "Atomichron: The Atomic Clock from Concept to Commercial Product" Paul Forman, 1985 https://ieeemilestones.ethw.org/w/images/8/8d/Forman_Proc_IEEE_1985.pdf "The First Atomic Clock Program: NBS, 1947-1954" Paul Forman, 1985 http://time.kinali.ch/ptti/1985papers/Vol%2017_01.pdf "A Historical Review of U.S. Contributions to the Atomic Redefinition of the SI Second in 1967" Michael Lombardi, 2017 https://tf.nist.gov/general/pdf/2917.pdf --- Now, back to the NAWCC article about Mike Bovarnick. I met Mike a few years ago when he made a presentation to a local NAWCC chapter. It is amazing (well, he is 97 now) that an original member of the team that built the first commercial cesium clock is still with us. I've arranged to talk with Mike, and since he's local, have him come over to see the Atomichron in my garage. It may be a huge trip down memory lane for him, reading the original manual, seeing the schematics again, touching the actual circuits that he designed and worked on. I have many questions for him about the early days of the development of atomic clocks, or electronics in general going back to the 50's. What that in mind, if any of you have questions for Mike please contact me off-list (tvb@leapsecond.com) and I'll sort them and make sure everyone's questions get answered during Mike's visit. This is a rare chance to talk with living history. And thanks again, Gary, for posting that NAWCC article about Mike and the Atomichron. /tvb [1] https://insidegnss.com/time-is-relative-position-absolute/