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ABOUT US
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Naval Oceanography One Pager
End of Year Graphic 2022
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USNO GPS Data Categories Explanation
CGGTTS Data Format
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GPS Information: SA, DGPS, Leap Seconds, etc.
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United States Naval Observatory
Precise Time Department
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Home
Our Commands
United States Naval Observatory
Precise Time Department
Global Positioning System
GPS Timing Data and Information
USNO Format Explanation
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 GPS Data Categories Explanation
Column
Data Category
Explanation
1
PRN
the satellite vehicle PRN number
2
MJD
the five digit Modified Julian Date and the fraction of day at the midpoint of the track
3
BGTK
HHMM
hour and minute (in UTC) of the start of the track
tracks begin at 1 second after the minute
4
TRK
SEC
the track length in seconds (a full track is 780 seconds)
5
MC-GPS
NS
the time difference (measured in nanoseconds) between UTC(USNO MC) and GPS time, referred to the midpoint of the pass via a linear fit
6
SLOPE
PS/S
the slope determined via the linear fit to produce MC-GPS (measured in picoseconds per second)
7
RMS
NS
the root mean square of the residuals of the linear fit used to produce MC-GPS
8
SAMP
N
the number of data points used in the fit to produce MC-GPS
9
EL
DG
the elevation (in degrees) of the satellite at the midpoint of the track
(data prior to MJD 50846 gives elevation at beginning of track)
10
AZM
DEG
the azimuth (in degrees) of the satellite at the midpoint of the track
(data prior to MJD 50846 gives azimuth at beginning of track)
11
ION
NS
the modeled ionospheric delay (measured in nanoseconds) referred to the midpoint of the pass via a linear fit
12
MC-SATCL
NS
the time difference (measured in nanoseconds) between UTC(USNO MC) and satellite time, referred to the midpoint of the pass via a linear fit
13
SLOPE
PS/S
the slope determined via the linear fit to produce MC-SATCL (measured in picoseconds per second)
14
TROP
NS
the modeled tropospheric delay (measured in nanoseconds) referred to the midpoint of the pass via a linear fit
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