[IGSREPORT-8727] Wk 1137 GPS Earth Orientation

[Dennis McCarthy]

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IGS Electronic Report   25 Oct 11:31:00 PDT 2001      Message Number 8727
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Author: IERS Rapid Service/Prediction Center
Subject: Earth Orientation Contributions to IERS Bulletin A
Date: 25 Oct 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 the ITRF and the ICRF reference frames by removing
a priori mean bias and rate.

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.    52201.79    18               0.001               0.027

GSFC Int.    52204.79    17              -0.004               0.025

IAA VLBI     52192.25     5  -0.02  0.02  0.001   0.14  0.16  0.004

GSFC VLBI    52192.25     6  -0.19 -0.06 -0.004   0.10  0.04  0.020

CSR SLR      52204.85    11  -0.13 -0.42 -0.011*  0.24  0.44  0.089*

TUD SLR      52200.00    10  -0.19 -0.09          0.28  0.28

IAA SLR      52205.00    30  -0.08  0.11          0.16  0.13

MCC SLR      52200.00    30   0.00 -0.20          0.14  0.12

IGS Final    52188.50    30   0.01  0.01          0.02  0.03

IGS Rapid    52207.50    19   0.00 -0.01          0.02  0.05

             52207.50     2              -0.003*              0.022*

USNO GPS     52206.75    32               0.003*              0.017*

EMR GPS      52206.50    22              -0.008*              0.034*

* 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          52201.5  30   0.10  0.30 -10.28  0.019   0.10  0.12   0.27  0.029

ESA          52195.5  30   0.05  0.37        -0.046   0.07  0.10         0.024

EMR          52195.5  30   0.02  0.09 -15.11 -0.033   0.12  0.12   0.35  0.019

GFZ          52202.5  30   0.02  0.21   0.01 -0.030   0.07  0.08   0.08  0.031

JPL          52195.5  30   0.04  0.24 -17.55 -0.026   0.08  0.07   0.25  0.026

NGS          52199.5  30  -0.07  0.07        -0.067   0.12  0.20         0.080

SIO          52195.5  30  -0.02  0.22        -0.035   0.08  0.08         0.019

USN (Rapid)  52205.5  29  -0.12  0.31        -0.057   0.11  0.13         0.023

USNO GPS UT  52206.5  30                0.71                       0.01

IGS Final    52188.5  30   0.01  0.19   0.00 -0.001   0.03  0.04   0.02  0.014

IGS Rapid    52205.5  30   0.00  0.20  -0.01  0.001   0.05  0.08   0.08  0.028

* 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   52154.   30  -0.01  0.01  0.004          0.04  0.05  0.025

97C04        52207.   30   0.04  0.07  0.013          0.07  0.08  0.030


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