The article mentions a "highly accurate chronometer" in regards to the Blackbird. So I don't think they deduce time from the stars. Rhubidium atomic clocks are

The article mentions a "highly accurate chronometer" in regards to the Blackbird. So I don't think they deduce time from the stars. Rhubidium atomic clocks are quite compact and not all that expensive. Hobbyist electronics people buy retired ones from cell phone base stations for an accurate 10 MHz sync signal in their home labs. https://www.eevblog.com/2012/01/14/eevblog-235-rubidium-frequency-standard/comment-page-4/ https://www.eevblog.com/2012/01/14/eevblog-235-rubidium-freq...