Definition of a Yuma Almanac

ID
PRN of the SVN
Health
000=usable
Eccentricity
This shows the amount of the orbit deviation from circular (orbit). It is the distance between the foci divided by the length of the semi-major axis (our orbits are very circular).
Time of Applicability
The number of seconds in the orbit when the almanac was generated. Kind of a time tag.
Orbital Inclination
The angle to which the SV orbit meets the equator (GPS is at approximately 55 degrees). Roughly, the SV's orbit will not rise above approximately 55 degrees latitude. The number is part of an equation: # = π/180 = the true inclination.
Rate of Right Ascension
Rate of change in the measurement of the angle of right ascension as defined in the Right Ascension mnemonic.
SQRT(A) Square Root of Semi-Major Axis
This is defined as the measurement from the center of the orbit to either the point of apogee or the point of perigee.
Right Ascension at Time of Almanac (TOA)
Right Ascension is an angular measurement from the vernal equinox ((OMEGA)0).
Argument of Perigee
An angular measurement along the orbital path measured from the ascending node to the point of perigee, measured in the direction of the SV's motion.
Mean Anomaly
Angle (arc) traveled past the longitude of ascending node (value = 0±180 degrees). If the value exceeds 180 degrees, subtract 360 degrees to find the mean anomaly. When the SV has passed perigee and heading towards apogee, the mean anomaly is positive. After the point of apogee, the mean anomaly value will be negative to the point of perigee.
af0
SV clock bias in seconds.
af1
SV clock drift in seconds per seconds.
Week
GPS week (0000–1023), every 7 days since 1999 August 22.

GPS Yuma Almanacs
1990
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1997
1998
1999
2000
2001
2002
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Dr. T.S. Kelso [TS.Kelso@celestrak.com]
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Last updated: 2014 May 17 03:15:52 UTC
Accessed 42,227 times since 2000 December 16
Current system time: 2017 April 28 10:21:32 UTC