[IGSREPORT-6318] Wk 1020 GPS Earth Orientation

[IERS]

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IGS Electronic Report    Fri Jul 30 12:32:23 PDT 1999      Message Number 6318
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Author: IERS Sub-bureau for Rapid Service and Predictions
Subject: Wk 1020 GPS Earth Orientation

Subject: Earth Orientation Contributions to IERS Bulletin A
Date: 29 Jul 99


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.    51385.71    23               -.004                .031

SPbU Int.    51383.71    20                .006                .031

NEOS VLBI    51380.25     5   -.17   .05  -.002    .18   .14   .004

CSR SLR      51369.08    10   -.25  -.12  -.013*   .30   .29   .073*

TUD SLR      51381.00    10   -.32   .03           .27   .23

IAA SLR      51386.00    30   -.09   .03           .19   .12

MCC SLR      51380.00    30    .22   .02           .10   .12

UTX LLR      51324.88     9                .063                .240

IGS Final    51376.50    30    .01   .00           .03   .03

IGS Rapid    51387.50    11    .04  -.01           .12   .09

             51387.50     2               -.008*               .002*

USNO GPS     51387.50    30               -.003*               .015*

EMR GPS      51387.50    22                .008*               .063*

* 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          51383.5  30    .29   .08   2.26   .006    .07   .06    .08   .010

ESA          51376.5  30    .35   .24         -.006    .12   .17          .023

EMR          51376.5  30    .22   .04 -17.17  -.001    .08   .13    .27   .025

GFZ          51383.5  30    .21   .02   -.07   .023    .07   .08    .06   .019

JPL          51376.5  30    .34  -.01 -15.61   .039    .07   .06    .40   .030

NGS          51381.5  31    .28  -.18          .005    .14   .23          .045

SIO          51376.5  30    .37   .09          .031    .09   .11          .029

USN (Rapid)  51387.5  30    .34   .12          .001    .13   .15          .028

USNO GPS UT  51387.5  30                1.14                        .02

IGS Final    51376.5  30    .31   .07    .00   .005    .05   .04    .01   .022

IGS Rapid    51387.5  30    .36   .10    .01   .005    .16   .12    .07   .025

* 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   51334.   30   -.05   .12   .006           .04   .04   .020

97C04        51386.   30   -.05   .23  -.016           .08   .06   .037


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


[Mailed From: Dennis McCarthy <dmc at maia.usno.navy.mil>]