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ABOUT US
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Naval Oceanography One Pager
End of Year Graphic 2022
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Precise Time Department
The USNO Master Clock
The USNO Master Clock
Time Dissemination at the USNO
USNO Alternate Master Clock (AMC)
Cesium Atomic Clocks
Hydrogen Masers at the USNO
Rubidium Fountain Clocks
USNO Time Scales
International Time Scales and the BIPM
Definitions of Systems of Time
Global Positioning System
Global Positioning System Overview
USNO GPS Data Categories Explanation
CGGTTS Data Format
USNO GPS Time Transfer
Leap Seconds
GPS Information: SA, DGPS, Leap Seconds, etc.
GPS Week Number Rollover
GPS Timing Data and Information
USNO Format Explanation
USNO Computer Display Clocks
Two-Way Satellite Time Transfer (TWSTT)
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Home
Our Commands
United States Naval Observatory
Precise Time Department
The USNO Master Clock
Home
Our Commands
United States Naval Observatory
Precise Time Department
The USNO Master Clock
ABOUT US
Mission & Vision
History
Naval Oceanography One Pager
End of Year Graphic 2022
LEADERSHIP
Commander
Technical Director
Command Master Chief
All Leadership
OUR COMMANDS
Naval Oceanographic Office
Fleet Numerical Meteorology & Oceanography Center
United States Naval Observatory
News from the Naval Observatory
Earth Orientation Department
Precise Time Department
The USNO Master Clock
The USNO Master Clock
Time Dissemination at the USNO
USNO Alternate Master Clock (AMC)
Cesium Atomic Clocks
Hydrogen Masers at the USNO
Rubidium Fountain Clocks
USNO Time Scales
International Time Scales and the BIPM
Definitions of Systems of Time
Global Positioning System
Global Positioning System Overview
USNO GPS Data Categories Explanation
CGGTTS Data Format
USNO GPS Time Transfer
Leap Seconds
GPS Information: SA, DGPS, Leap Seconds, etc.
GPS Week Number Rollover
GPS Timing Data and Information
USNO Format Explanation
USNO Computer Display Clocks
Two-Way Satellite Time Transfer (TWSTT)
Telephone Time
Network Time Protocol (NTP)
US Eastern Time Zone NTP Servers
US Mountain Time Zone Servers
DoD Customer Servers
Astronomical Applications Department
Celestial Reference Frame Department
Senior Enlisted Advisor
Careers at the USNO
Naval Oceanography Operations Command
Fleet Weather Center - Norfolk
National Ice Center
Fleet Weather Center - San Diego
Joint Typhoon Warning Center
Naval Oceanography Anti-Submarine Warfare Center
Navy DoD Supercomputing Resource Center
PRESS ROOM
News Stories
Photo Gallery
Video Gallery
Public Use of Limitations
CONTACT US
USNO Master Clock
The USNO Master Clock is the underlying product for all of our precise time and time interval products. The timing reference produced by this timing ensemble is called UTC(USNO). This timing reference is mandated to be the precise time reference for all of the DoD.
USNO Master Clock Description
Technical information about the physical components that make up our timing ensemble.
USNO Time Scales
Descriptions of the time scales determined at USNO and their relationships.
International Time Scales and the BIPM
Information about the relationship between international time scales and the USNO products. This section includes data files and plots of these time scales.
Definitions of Systems of Time
Definitions of systems for determining and referencing times. These range from atomic time scales to the rotation of the Earth.
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