[IGSREPORT-7983] Wk 1100 GPS Earth Orientation

[Dennis McCarthy]

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IGS Electronic Report   08 Feb 11:42:00 PST 2001      Message Number 7983
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Author: IERS Rapid Service/Prediction Center
Subject: Earth Orientation Contributions to IERS Bulletin A
Date:  8 Feb 01


In this report, individual Earth orientation time series are compared
to the IERS Bulletin A combination.  For further information, including
the raw time series, refer to http://maia.usno.navy.mil/bulletin-a.html.

The first table below shows some comparison results for those series
included in Bulletin A during the last 30 days.  All data are aligned to
the system defined by ITRF94 and the current ICRF by removing a priori mean
bias, rate, annual and semiannual terms.

Units: milliseconds of arc for x, y; milliseconds of time for UT1-UTC

Contributor   Latest      #         Mean          Standard Deviation
Series         Day               (series-BullA)
                                x     y  UT1-UTC    x     y  UT1-UTC

NEOS Int.    51882.80    12               -.009                .014

SPbU Int.    51941.80    16                .002                .046

GSFC Int.    51942.80    18                .018                .019

NEOS VLBI    51863.25     4   -.20   .11   .006    .07   .12   .008

IAA VLBI     51926.25     5   -.11   .04  -.002    .10   .11   .003

GSFC VLBI    51926.00     5    .05   .02   .000    .15   .07   .005

CSR SLR      51944.88    10    .15   .08  -.094*   .35   .54   .128*

TUD SLR      51942.00    10    .31   .33           .37   .44

IAA SLR      51946.00    30   -.20  -.14           .25   .19

MCC SLR      51941.00    30    .09   .00           .21   .26

UTX LLR      51867.16     5                .010                .225

IGS Final    51929.50    30    .01   .00           .02   .02

IGS Rapid    51948.50    19    .01   .00           .02   .03

             51948.50     5               -.001*               .036*

USNO GPS     51947.75    32               -.001*               .015*

EMR GPS      51947.50    22                .030*               .048*

* All satellite techniques provide information on the rate of change of
  Universal Time contaminated by effects due to unmodelled orbit node
  motion.  VLBI-based results have been used to minimize drifts in UT
  estimates.


The following tables show comparisons for other related time series during
the last 30 days.  All IGS series are final solutions except for the USNO
series.  No a priori systematic corrections have been applied.

Units: milliseconds of arc for x, y; milliseconds of time for UT, LOD 

IGS           Latest   #              Mean                Standard Deviation
Series         Day               (series-BullA)
                             x     y     UT*    LOD*    x     y      UT*   LOD*

COD          51943.5  30    .05   .24  -7.88   .003    .09   .08    .05   .016

ESA          51943.5  30    .00   .41         -.033    .12   .09          .030

EMR          51936.5  30   -.03   .18 -21.66  -.026    .11   .07    .40   .031

GFZ          51943.5  30    .00   .28    .01  -.002    .07   .09    .05   .025

JPL          51936.5  30    .04   .22 -19.22  -.020    .05   .08    .21   .032

NGS          51943.5  30   -.06   .17          .004    .18   .17          .052

SIO          51936.5  30    .04   .27          .007    .05   .09          .019

USN (Rapid)  51947.5  27    .14   .32         -.026    .13   .12          .055

USNO GPS UT  51947.5  30                 .12                        .05

IGS Final    51929.5  30    .02   .24    .00   .001    .03   .03    .01   .018

IGS Rapid    51947.5  30    .03   .23    .00   .004    .05   .05    .07   .055

* All satellite techniques provide information on the rate of change of
  Universal Time contaminated by effects due to unmodelled orbit node
  motion.  The UT results for COD and JPL are integrations of LOD estimates.
  EMR estimates UT and LOD separately by applying a priori orbit constraints.
  GFZ and IGS use VLBI-based results to minimize drifts in their UT estimates
  and thus the standard deviations are not representative of the intrinsic
  capabilities of GPS alone for monitoring UT variations.  USNO estimates
  UT using long-term models for orbit plane rotations.


IERS Earth Orientation Center Series:

Series       Latest    #          Mean                Standard Deviation
              Day            (series-BullA)
                             x     y  UT1-UTC           x     y  UT1-UTC

Bulletin B   51914.   30    .01   .02  -.010           .06   .05   .052

97C04        51948.   30   -.06   .07   .012           .20   .07   .034


Plots of the residuals are available at http://maia.usno.navy.mil/plots.html.
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The IERS Rapid Service/Prediction Center is an activity of the Earth
Orientation Department at the U.S. Naval Observatory.
--
Dennis D. McCarthy                       dmc at maia.usno.navy.mil
Director, Directorate of Time            phone: (202) 762-1837
U.S. Naval Observatory                   fax: (202) 762-1563
Washington, DC 20392-5420