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pole.

Table of X and Y pole values

Overview

Slight changes in the orientation of the Earth's crust (and therefore the sites and the reference frame they define) relative to the spin axis of the Earth cause systematic changes between tracking stations and the GPS satellites. These Earth Orientation Parameters (EOP's) are significant to and detectable in GPS processing.

Several sources for measured and predicted EOP's exist. The most common source for NOAA orbit production is the NEOS Bulletin A from the U.S. Naval Observatory. This information is reformated and the pole. and UT1. files created. The pole. file simply lists the X and Y pole rotations during some time span. The file is ASCII.

Example 

(9508.04) Created at 09/12/96 11:40:02.00 from ser7.96256
(5X,I5,8I7,12X,I2)                 2450303 2450352  4  1          1.E-05
     50303  26941  43211  27207  42880  27414  42483  27589  42151             4
     50307  27759  41793  27955  41459  28184  41126  28396  40761             4
     50311  28567  40409  28703  40053  28827  39681  28963  39315             4
     50315  29097  38964  29233  38650  29353  38243  29463  37897             4
     50319  29564  37564  29638  37202  29685  36815  29708  36399             4
     50323  29728  36030  29758  35561  29774  35119  29754  34640             4
     50327  29715  34193  29674  33768  29627  33309  29565  32937             4
     50331  29511  32462  29453  32076  29393  31668  29324  31293             4
     50335  29250  30898  29192  30525  29141  30140  29105  29748             4
     50339  29062  29358  29013  28968  28957  28580  28896  28192             4
     50343  28828  27806  28754  27422  28673  27039  28587  26657             4
     50347  28494  26277  28396  25898  28291  25522  28180  25147             4
     50351  28063  24774  27940  24403                                         2
where:

Line 1 is a descriptive header.

Line 2 gives the format for reading the file, the Julian date of the first and last entry, the number of entries per line, the interval between entries (days), and the scaling factor all entries.

Thereafter, each line has the modified Julian day number for the first values on each line, the X and Y pole pairs. The last number on each line is the number of X and Y pole pairs on that line. A blank in this last field implies the maximum, i.e. the number of entries per line given on line 2.
NOTE: entry * scaling factor = arc seconds 

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pole.html
January 14, 2000
Steve Hilla