[IGSREPORT-7922] Wk 1097 GPS Earth Orientation

[Dennis McCarthy]

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IGS Electronic Report   19 Jan 06:46:17 PST 2001      Message Number 7922
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Author: IERS Rapid Service/Prediction Center
Subject: Earth Orientation Contributions to IERS Bulletin A
Date: 18 Jan 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               -.008                .015

SPbU Int.    51914.80    14               -.002                .029

GSFC Int.    51921.81    14                .010                .037

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

IAA VLBI     51912.25     5   -.15   .05   .000    .12   .11   .001

GSFC VLBI    51912.00     5    .04  -.02   .001    .14   .10   .006

CSR SLR      51923.71    11   -.07   .22  -.090*   .37   .42   .091*

TUD SLR      51912.00    10    .02   .07           .33   .30

IAA SLR      51925.00    30   -.24   .02           .25   .19

MCC SLR      51920.00    30    .04   .00           .19   .28

UTX LLR      51867.16     5                .011                .224

IGS Final    51908.50    30    .02   .00           .04   .02

IGS Rapid    51927.50    18    .00  -.03           .02   .08

             51927.50     5                .006*               .011*

USNO GPS     51926.75    32               -.010*               .017*

EMR GPS      51926.50    22                .010*               .039*

* 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          51922.5  30    .12   .21  -7.92   .003    .13   .12    .07   .014

ESA          51922.5  30    .01   .33         -.019    .13   .16          .022

EMR          51915.5  30    .00   .17 -22.49  -.013    .10   .14    .27   .024

GFZ          51922.5  30   -.02   .31   -.06   .014    .07   .07    .09   .024

JPL          51915.5  30    .02   .18 -19.58  -.013    .08   .07    .13   .026

NGS          51919.5  30    .05   .17         -.032    .17   .27          .057

SIO          51915.5  30    .02   .31          .004    .08   .08          .015

USN (Rapid)  51926.5  27    .18   .27         -.019    .13   .09          .029

USNO GPS UT  51926.5  30                 .17                        .02

IGS Final    51908.5  30    .04   .25   -.01   .003    .05   .02    .03   .016

IGS Rapid    51926.5  30    .04   .17   -.01  -.001    .10   .14    .08   .022

* 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   51879.   30    .02   .05  -.019           .03   .04   .033

97C04        51909.   30   -.01   .02  -.008           .06   .06   .051


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