[IGSREPORT-8206] Wk 1111 GPS Earth Orientation

[Dennis McCarthy]

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IGS Electronic Report   26 Apr 13:13:23 PDT 2001      Message Number 8206
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Author: IERS Rapid Service/Prediction Center
Subject: Earth Orientation Contributions to IERS Bulletin A
Date: 26 Apr 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.    52015.80    16               -.004                .013

GSFC Int.    52012.80    17                .007                .011

IAA VLBI     51996.25     5   -.17   .07  -.002    .19   .03   .003

GSFC VLBI    52003.00     5    .08   .02   .002    .11   .10   .004

CSR SLR      52019.61    11    .09   .15  -.023*   .50   .49   .173*

TUD SLR      52017.00    10    .18   .26           .31   .40

IAA SLR      52019.00    30   -.02  -.04           .20   .14

MCC SLR      52018.00    30    .07  -.03           .17   .20

UTX LLR      51867.16     5                .010                .225

IGS Final    52006.50    30    .00  -.01           .02   .02

IGS Rapid    52025.50    19    .00   .00           .02   .03

             52025.50     9               -.001*               .021*

USNO GPS     52024.75    32               -.007*               .020*

EMR GPS      52024.50    22               -.029*               .046*

* 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          52018.5  30   -.02   .14  -8.89   .011    .11   .08    .10   .012

ESA          52020.5  30    .00   .14         -.034    .11   .08          .022

EMR          52006.5  30   -.01   .16 -18.81  -.041    .09   .10    .34   .021

GFZ          52020.5  30   -.04   .26   6.24  -.005    .05   .09   2.01   .028

JPL          52013.5  30    .00   .18 -18.38   .005    .06   .08    .09   .029

NGS          52017.5  30   -.10  -.06         -.017    .19   .19          .049

SIO          52013.5  30    .00   .24          .021    .07   .08          .017

USN (Rapid)  52023.5  29    .00   .33         -.037    .12   .17          .032

USNO GPS UT  52024.5  30                -.07                        .03

IGS Final    52006.5  30    .01   .24    .00   .004    .03   .04    .02   .020

IGS Rapid    52023.5  30   -.01   .23    .03  -.003    .07   .06    .07   .026

* 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   51969.   30   -.01   .07  -.012           .05   .05   .019

97C04        52025.   30    .00   .04  -.019           .06   .10   .036


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