[IGSREPORT-7681] Wk 1085 GPS Earth Orientation

[Dennis McCarthy]

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IGS Electronic Report   26 Oct 12:34:01 PDT 2000      Message Number 7681
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Author: IERS Sub-bureau for Rapid Service and Predictions

Subject: Earth Orientation Contributions to IERS Bulletin A
Date: 26 Oct 00


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.  (No corrections are applied to 
the NEOS VLBI and the NEOS Intensives series for UT1-UTC.)

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.    51840.80    17               -.012                .049

SPbU Int.    51837.80    27               -.009                .038

NEOS VLBI    51828.25     5   -.21   .06   .001    .22   .11   .003

IAA VLBI     51821.25     5   -.02   .18   .003    .20   .11   .005

CSR SLR      51837.34    10   -.50  -.22  -.098*   .31   .71   .134*

TUD SLR      51837.00    10    .26   .28           .30   .54

IAA SLR      51841.00    30   -.11  -.18           .20   .21

MCC SLR      51836.00    30    .10  -.34           .11   .17

UTX LLR      51781.16     6                .071                .133

IGS Final    51824.50    30    .00  -.01           .06   .03

IGS Rapid    51842.50    18    .01   .00           .04   .02

             51842.50     2               -.002*               .008*

USNO GPS     51842.75    32               -.002*               .013*

* 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          51838.5  30    .08   .19  -8.05  -.003    .09   .08    .08   .011

ESA          51838.5  30    .07   .36         -.040    .12   .08          .017

EMR          51838.5  30    .06   .15 -25.47  -.023    .10   .13    .20   .016

GFZ          51838.5  30   -.01   .28    .01  -.013    .07   .08    .05   .021

JPL          51831.5  30   -.01   .20 -20.26   .006    .08   .09    .07   .021

NGS          51837.5  30   -.05   .15         -.045    .17   .18          .057

SIO          51831.5  30    .00   .20          .009    .09   .08          .032

USN (Rapid)  51842.5  30    .10   .36         -.043    .10   .17          .023

USNO GPS UT  51842.5  30                1.67                        .03

IGS Final    51824.5  30    .01   .24    .00   .001    .08   .05    .01   .017

IGS Rapid    51842.5  30    .04   .21    .05  -.012    .08   .08    .08   .018

* 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 Central Bureau Series:

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

Bulletin B   51789.   30    .00   .04  -.004           .03   .03   .015

97C04        51843.   30   -.01   .04  -.018           .07   .11   .043


Plots of the residuals are available at http://maia.usno.navy.mil/plots.html.
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The IERS Sub-bureau for Rapid Service and Prediction is an activity of the
National Earth Orientation Service and is performed by 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