Editing Department of Defense master clock

{{Short description|Atomic master clock for the U.S. Department of Defense}}
[[Image:Usno-mc.jpg|thumb|right|The master atomic clock ensemble at the [[United States Naval Observatory|U.S. Naval Observatory]] in [[Washington D.C.]], which provides the time standard for the U.S. Department of Defense.<ref>[https://web.archive.org/web/20090303034541/http://www.usno.navy.mil/USNO/time/master-clock USNO Master Clock]</ref> The rack mounted units in the background are caesium beam clocks. The black units in the foreground are [[hydrogen maser]] standards.]]

The '''Department of Defense master clock''' is the [[Atomic clock|atomic]] [[master clock]] to which [[time]] and [[frequency]] measurements for the [[United States Department of Defense]] are referenced.

Located in Washington D.C., the [[United States Naval Observatory|U.S. Naval Observatory]] master clock is designated as the "DOD Master Clock". It is one of the two [[standardization|standard]] time and frequency references for the [[Federal government of the United States|U.S. Government]] in accordance with Federal Standard 1002-A. The other standard time and frequency reference for the U.S. Government is the [[National Institute of Standards and Technology]] (NIST) master clock.

The U.S. Naval Observatory also maintains an alternate clock designated "USNO Alternate Master Clock" at [[Schriever Space Force Base]], [[Colorado]].<ref>{{Cite web|url=https://www.cnmoc.usff.navy.mil/Our-Commands/United-States-Naval-Observatory/Precise-Time-Department/The-USNO-Master-Clock/The-USNO-Master-Clock/Time-Dissemination-at-the-USNO/USNO-Alternate-Master-Clock-AMC/|title=USNO Alternate Master Clock (AMC)|date=1 July 2023|website=Navy.mil}}</ref>

==References==
{{FS1037C MS188}} 
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[[Category:Clocks in the United States]]
[[Category:United States Department of Defense]]