Subject: [IGSREPORT-7741] Wk 1088 GPS Earth Orientation
From: Dennis McCarthy <[email-masked]>
To: [email-masked]
Date: Thu, 16 Nov 2000 13:50:12 EST

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IGS Electronic Report   16 Nov 10:50:14 PST 2000      Message Number 7741
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Author: IERS Sub-bureau for Rapid Service and Predictions

Subject: Earth Orientation Contributions to IERS Bulletin A
Date: 16 Nov 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.    51861.81    14               -.016                .043

SPbU Int.    51854.80    17               -.003                .041

NEOS VLBI    51849.25     5   -.22   .07  -.001    .17   .13   .003

IAA VLBI     51849.25     5    .04   .05   .000    .15   .19   .007

CSR SLR      51861.16    10    .00   .04   .082*   .57   .30   .134*

TUD SLR      51849.00    10    .30   .08           .38   .43

IAA SLR      51861.00    30   -.10  -.15           .22   .24

MCC SLR      51857.00    30    .14  -.41           .11   .16

UTX LLR      51840.21     6               -.005                .096

IGS Final    51845.50    30    .01   .00           .06   .03

IGS Rapid    51864.50    19    .01  -.01           .07   .05

             51864.50     2               -.001*               .005*

USNO GPS     51863.75    32               -.003*               .022*

* 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          51859.5  30    .16   .17  -8.09  -.004    .07   .09    .07   .016

ESA          51852.5  30    .01   .35         -.028    .10   .12          .020

EMR          51852.5  30    .03   .15 -25.10  -.022    .11   .12    .24   .017

GFZ          51859.5  30   -.08   .26   -.01  -.009    .09   .07    .07   .027

JPL          51852.5  30    .02   .18 -20.35   .001    .08   .07    .04   .026

NGS          51858.5  30    .01   .21         -.053    .17   .20          .049

SIO          51852.5  30    .01   .18         -.021    .07   .08          .014

USN (Rapid)  51863.5  28    .15   .33         -.035    .12   .16          .023

USNO GPS UT  51863.5  30                1.72                        .03

IGS Final    51845.5  30    .02   .24    .00  -.008    .07   .05    .01   .018

IGS Rapid    51863.5  30    .02   .19   -.01   .000    .10   .10    .08   .027

* 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   51683.   30    .03  -.03  -.012           .03   .05   .038

97C04        51683.   30    .03  -.03  -.007           .03   .05   .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                       [email-masked]
Director, Directorate of Time            phone: (202) 762-1837
U.S. Naval Observatory                   fax: (202) 762-1563
Washington, DC 20392-5420