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SLR-Report No.5754

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Date:2005-08-03 13:15:00
Sender:Ron Noomen <Ron Noomen <ron@astro.lr.tudelft.nl>>
Subject:[SLR-Report] No. 5754: Delft QL Report August 03, 2005
Author:Ron Noomen
Content:********************************************************************************
SLR Electronic Report 2005-08-03 13:15:00 UTC Message No. 5754
********************************************************************************

Author: Ron Noomen
Subject: Delft QL Report August 03, 2005


WEGENER-2 IERS

REPORT OF THE QUICK-LOOK DATA ANALYSIS CENTER
DELFT UNIVERSITY OF TECHNOLOGY
FACULTY OF AEROSPACE ENGINEERING
THE NETHERLANDS


August 3, 2005


This is a daily report, presenting the results of a continuing analysis of the
most recent global LAGEOS-1 and LAGEOS-2 quick-look laser ranging data. The
report consists of (A) a pass summary, (B) an overview of the analysis results,
detailed statistics of the analysed measurements, and an accumulative pass
overview and (C) the earth rotation parameter solutions submitted to IERS. The
report is based on all quick-look data as received until Wed, Aug 3, 2005.
Questions and comments should be addressed to:

R. Noomen
Delft University of Technology
Faculty of Aerospace Engineering
Delft Institute for Earth-Oriented Space Research
Kluyverweg 1
2629 HS Delft
The Netherlands

Telephone: +31-15-2785377
Telefax : +31-15-2785322
E-mail : ron.noomen@deos.tudelft.nl


A. PASS SUMMARY

The table below gives an overview of the ranging data both on LAGEOS-1 and
LAGEOS-2, as received by the Quick-Look Data Analysis Center (QLDAC) on Wed,
Aug 3, 2005. All data were obtained through the NASA Crustal Dynamics Data
Information system (CDDIS) and the Eurolas Data Center (EDC) in Germany.
The data are unscreened and may span more than a week due to late reporting
by the stations.

------------------------------------------------------------------------------
Station System/Location Period No. of Passes
ID LAGEOS-1 LAGEOS-2
------------------------------------------------------------------------------
1864 Maidanak, Uzbekistan (site 2) 050801 - 050801 1 -
1873 Simeiz, Crimea, Ukraine 050802 - 050802 1 -
1884 Riga, Latvia 050802 - 050802 1 -
1893 Kazivili, Crimea, Ukraine 050801 - 050801 1 -
6810 Zimmerwald 846, Switzerland 050801 - 050801 - 1
7080 McDonald Obs., Fort Davis, TX 050802 - 050802 1 -
7090 Yarragadee, Australia 050801 - 050801 2 2
7105 Greenbelt, Maryland 050802 - 050802 3 -
7110 Monument Peak, California 050801 - 050801 2 1
7355 Urumqi, China (TROS) 050801 - 050801 2 -
7810 Zimmerwald 423, Switzerland 050801 - 050801 - 1
7811 Borowiec, Poland 050801 - 050802 3 -
7824 San Fernando, Spain 050731 - 050802 4 -
7825 Mount Stromlo, Australia 050801 - 050802 7 6
7832 Riyad, Saudi Arabia 050801 - 050803 4 3
7838 Simosato Observatory, Japan 050801 - 050801 1 -
7839 Graz, Austria 050801 - 050803 6 3
7840 Herstmonceux, United Kingdom 050802 - 050803 7 2
7841 Potsdam, Germany 050801 - 050802 2 -
8834 Wettzell, Germany 050801 - 050802 3 3
------ ------ --- ---
TOTAL 050731 - 050803 51 22
------------------------------------------------------------------------------


B. ANALYSIS RESULTS

The analysis is based on two orbit solutions using global quick-look normal
points that cover a period of 8 days which are computed simultaneously. This
week´s data interval runs from Tue, Jul 26, 2005 to Wed, Aug 3, 2005. The
measurement and dynamic models used in this analysis are close to the IERS
Standard. The overall model is referred to as QLDACMOD11. The details of this
model can be obtained on request. The terrestrial reference frame is provided
by the ITRF2000 station coordinates solution (extended with coordinates
of new stations, where necessary).

The general statistics and results of this week´s analysis are thus:

-----------------------------------------------------------------------
Satellite LAGEOS-1 LAGEOS-2
Number of Stations 0 0
Number of Passes 0/ 0 0/ 0
Number of Normal Points 0/ 0 0000/ 0
Weighted RMS of Fit (mm) 0 0
-----------------------------------------------------------------------


Residual statistics per station. The header line for each station shows
the station id, its name, whether the position is solved for or not and the
measurement accuracy in mm. Rejected observations are not used for the
calculation of the rms-of-fit, the biases or the scatter. The latter holds
w.r.t. the residual trend line described by the bias estimates. Uncertainties
are 3-sigma values.

--------------------------------------------------------------------------------
Date Time Sat. Obs. RMS Range Bias Time Bias Scatter
tot/rej (mm) (mm) (us) (mm)
--------------------------------------------------------------------------------



Distribution of daytime, nighttime and twilight passes since Jan 1, 2003:
--------------------------------------------------------------------------
Station System Period Number of Passes
LAGEOS-1 LAGEOS-2
Day/Night/Twil. Day/Night/Twil. Total
--------------------------------------------------------------------------
1824 KIEVLA 050112 - 050404 0/ 9/ 0 0/ 14/ 0 23
1831 LVIL 050117 - 050718 0/ 27/ 0 0/ 20/ 0 47
1864 MD2LAS 050110 - 050801 0/ 64/ 0 0/ 46/ 0 110
1873 SIMLAS 050316 - 050802 0/ 24/ 0 0/ 14/ 0 38
1884 RIGLAS 050104 - 050802 0/ 38/ 0 3/ 42/ 3 86
1893 CRMLAS 050731 - 050801 0/ 2/ 0 0/ 0/ 0 2
6405 TIGO 050104 - 050706 7/ 18/ 2 8/ 21/ 2 58
6810 ZIMLAT 050101 - 050801 193/111/ 20 151/ 70/ 17 562
7080 MLRS25 050101 - 050802 36/ 62/ 4 25/ 67/ 8 202
7090 ML0514 050101 - 050801 109/349/ 27 105/244/ 21 855
7105 ML0725 050108 - 050802 1/ 36/ 3 13/ 54/ 5 112
7110 ML0414 050118 - 050801 79/106/ 17 39/103/ 10 354
7124 ML0819 050118 - 050622 0/ 29/ 0 0/ 9/ 0 38
7237 CHALAS 050102 - 050723 0/ 59/ 1 0/ 71/ 0 131
7249 BEJLAS 050101 - 050705 0/ 55/ 0 0/ 69/ 0 124
7308 CRLLAS 050111 - 050510 7/ 5/ 1 1/ 10/ 0 24
7355 TROS02 050603 - 050801 0/ 34/ 0 0/ 7/ 0 41
7405 TIGO 050105 - 050705 5/ 26/ 0 3/ 7/ 0 41
7501 ML0616 050117 - 050721 40/110/ 3 40/ 87/ 7 287
7806 METLAS 050301 - 050301 0/ 0/ 0 0/ 1/ 0 1
7810 ZIMLAT 050101 - 050801 172/110/ 18 146/ 64/ 16 526
7811 POLLAS 050111 - 050802 0/ 46/ 0 0/ 39/ 0 85
7824 SPNLAS 050108 - 050802 4/ 92/ 0 1/ 92/ 3 192
7825 STL3 050101 - 050802 211/310/ 30 176/204/ 23 954
7832 SALRO 050101 - 050803 72/168/ 12 103/174/ 19 548
7835 GRASSE 050104 - 050705 0/ 32/ 2 0/ 33/ 3 70
7837 CHILAS 050102 - 050414 0/ 22/ 0 0/ 40/ 1 63
7838 SHOLAS 050106 - 050801 46/ 63/ 1 24/ 77/ 4 215
7839 AUSLAS 050103 - 050803 150/104/ 13 92/ 90/ 13 462
7840 RGOLAS 050102 - 050803 174/100/ 20 119/ 90/ 20 523
7841 GFZLA3 050105 - 050802 43/ 40/ 10 17/ 61/ 8 179
7848 FTLR06 050515 - 050719 4/ 30/ 0 3/ 10/ 0 47
7941 MLROnn 050102 - 050725 49/ 84/ 5 70/ 92/ 18 318
8834 WLRS01 050109 - 050802 156/109/ 17 129/103/ 19 533
--------------------------------------------------------------------------


C. EARTH ROTATION PARAMETER SOLUTIONS FOR IERS

The following solutions for the polar motion and the UT1-UTC time difference
were also obtained in the 10-day data arc analysis described in the previous
section. Only solutions submitted to IERS are presented here.




D. COMMENTS

1. The analysis covered in this report is based on a new set of station
coordinates: instead of the solution SSC(DUT)93L05, which was extrapolated
over some 10 years beyond the epoch of the latest observations, the current
analysis relies on the ITRF2000 solution.
Tests performed during the last year show that the rms-of-fit that can be
obtained when using ITRF2000 can be reduced to about 2 cm (instead of the
3+ cm which was achieved with the old model, for present-day epochs). Other
model modifications are to be expected. We hope to serve the community with
this development.

2. As of July 1, 2003, a new computation model and analysis strategy are in use:
in terms of geometric modeling, models for ocean loading and
atmospheric pressure loading have been turned on. The frequency of the
solutions for the Earth Orientation Parameters has been increased to
once per day (rather than once per 3 days). As a consequence, the arc
length has been changed from 10 days to 8 days. Also, the empirical
accelerations acting on the spacecraft are estimated twice per arc
(i.e. for 4-day periods). To absorb (unmodeled) geocenter motion,
3 coefficients of the gravity field model are estimated: C(1,0),
C(1,1) and S(1,1). Finally, the overall weighting scheme for the
individual SLR observations is also modified slightly.

3. As of the same date, provisions for handling the dual-wavelength systems
7405 and 7810 properly have been installed. This is done by introducing
dummy station ids 6405 and 6810 for the observations taken on 2nd wavelength.
The specific analysis results are easily recognizable because the wavelength
has been added to the printout of the station name.

4. As of July 7, 2004, similar provisions for handling the dual-wavelength syste
7941 properly have been installed. This is done by introducing a
dummy station id 6941 for the observations taken on 2nd wavelength.


From: Ron Noomen

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