Long-term performance of the Johns Hopkins-built hydrogen maser

Long-term performance data has been taken of the NR-6 Johns Hopkins-built hydrogen maser. Data on frequency stability relative to the ensemble of worldwide atomic standards whose data are reported by The Bureau of International de l'Heure (BIH) [1] spans two years. As a clock, this instrument has performed as well as the best standards of Germany and Canada who also report performance through the BIH.