[IGSREPORT-8230] Wk 1112 GPS Earth Orientation

[Dennis McCarthy]

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IGS Electronic Report   03 May 12:05:28 PDT 2001      Message Number 8230
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Author: IERS Rapid Service/Prediction Center
Subject: Earth Orientation Contributions to IERS Bulletin A
Date:  3 May 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

SPbU Int.    52026.80    18               -.001                .022

GSFC Int.    52025.80    16                .005                .016

IAA VLBI     52010.25     5   -.05   .11  -.001    .21   .12   .004

GSFC VLBI    52017.00     5   -.11  -.02   .000    .14   .06   .002

CSR SLR      52028.93    11    .06   .05  -.027*   .29   .42   .088*

TUD SLR      52026.00    10    .01   .40           .41   .52

IAA SLR      52030.00    30   -.06   .20           .25   .21

MCC SLR      52023.00    30    .02  -.03           .15   .20

UTX LLR      51867.16     5                .006                .223

IGS Final    52013.50    30    .00  -.01           .06   .08

IGS Rapid    52032.50    19    .01   .00           .07   .09

             52032.50     5               -.007*               .009*

USNO GPS     52031.75    32               -.005*               .026*

EMR GPS      52031.50    22                .004*               .022*

* 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          52027.5  30   -.02   .16  -8.96   .009    .11   .06    .06   .014

ESA          52020.5  30    .02   .13         -.033    .11   .12          .023

EMR          52020.5  30    .01   .17 -18.35  -.034    .11   .13    .23   .018

GFZ          52020.5  30   -.03   .26   6.24  -.004    .06   .09   2.01   .030

JPL          52020.5  30    .02   .20 -18.40   .001    .07   .09    .07   .030

NGS          52026.5  30   -.11  -.04         -.009    .21   .21          .045

SIO          52020.5  30    .04   .21          .020    .08   .09          .018

USN (Rapid)  52030.5  29    .04   .31         -.031    .13   .17          .037

USNO GPS UT  52031.5  30                -.04                        .05

IGS Final    52013.5  30    .01   .24    .00  -.001    .06   .08    .02   .018

IGS Rapid    52030.5  30    .02   .24    .01  -.003    .09   .11    .07   .030

* 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   52004.   30   -.01   .03   .003           .07   .06   .026

97C04        52032.   30    .02   .04  -.012           .07   .17   .028


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