**ASI/CGS associate analysis center for ILRS**

G. Bianco, R. Devoti, V. Luceri, P. Rutigliano, C. Sciarretta, F.Vespe

# INTRODUCTION

As an associate ILRS Analysis Center, the Space Geodesy Center \"G.
Colombo\" (CGS), of the Italian Space Agency (ASI), is mainly involved
in the areas of tectonic plate motion, Earth rotation and polar motion,
time variations of the Earth's gravitational field and satellite orbit
determination, as outlined in the next.

The CGS is also strengthening its geodetic capabilities with the
acquisition of a new powerful SLR system: the Matera Laser Ranging
Observatory (MLRO). It has been installed and is currently under the
validation phase, but some analyses have already been made using its
data.

Other information on the CGS and some of the analysis results are
available at the CGS WWW server GeoDAF (Geodetical Data Archive
Facility, [http://geodaf.mt.asi.it)]().

**DATA PRODUCTS PROVIDED**

-   estimated coordinates (SSC) of the global SLR tracking network and
    the Earth Orientation Parameters (EOP) submitted for the AWG pilot
    project;

-   estimated coordinates and velocity field (SSC/SSV) of the global SLR
    tracking network and the Earth Orientation Parameters (EOP)
    submitted to the ITRF-2000 frame realization;

-   the monthly estimated EOP provided to the IERS for the Bulletin B;

-   low degree geopotential zonal rates from the analysis of different
    geodetic satellites as a contribution to the definition of the Earth
    mantle viscosity profile;

-   estimation of tectonic movements and strain-rates in the
    Mediterranean area combining SLR, GPS and VLBI results obtained at
    CGS;

-   test solution of SSC and EOP time series for the IERS pilot project
    on coordinate and EOP combination;

## CURRENT ACTIVITIES

-   AWG Pilot project: the CGS is currently involved in the activities
    of the AWG pilot projects with the submission of coordinate/EOP test
    solutions and great effort is being made in the
    comparison/combination of the submitted solutions.

-   International Terrestrial Reference System (ITRS) maintenance: the
    production of IERS oriented products (global SSC/SSV and EOP time
    series) is regularly performed to assure the CGS contribution to the
    reference frames establishment.

-   Earth's gravitational field: in cooperation with other universities,
    the CGS is providing zonal drifts of the gravity field based on a
    long lasting data set of geodetic satellites. This solution is
    providing boundary values for the study of the rheology of the
    Earth.

-   Satellite rotation: the validation of the MLRO data has been
    undertaken and the acquired data will be soon available to the
    scientific community. The high single shot precision of the system
    gave the opportunity to study the satellite rotation: the first
    LAGEOS observations revealed a strong rotational signal on the order
    of a few mm RMS.

-   Geodetic solution combination: the combination algorithms are being
    tuned with the aim to build a unique SSC/SSV solution for the
    Mediterranean area, taking into account all the available solutions
    from different analysis groups.

**FUTURE PLANS**

-   A new solution of geopotential zonal drifts is foreseen with updated
    data set and a new analysis strategy.

-   So far, the capability of measuring the rotation of the LAGEOS has
    been demonstrated and further capabilities of MLRO data have to be
    exploited. It has been recognized that the interpretation of streak
    camera observations could help in estimating the attitude of the
    tracked satellite.

-   The LLR data analysis activities will soon start together with the
    MLRO lunar tracking.

-   Two color SLR observations for tropospheric studies has also been
    planned for the near future.

## Most recent pubblications:

1.  R. Devoti, M.Fermi, C.Ferraro, R.Lanotte V.Luceri, A.Nardi,
    R.Pacione, P.Rutigliano, C.Sciarretta, G.Bianco, F.Vespe, Height
    Time Series of the Italian GPS Fiducial Network compared with VLBI
    and SLR Estimations, In: Towards an Integrated Global Geodetic
    Observing System (IGGOS), IAG Symposia (120) 130-133, 2000

2.  R. Devoti, M.Fermi, C.Ferraro, R.Lanotte V.Luceri, A.Nardi,
    R.Pacione, P.Rutigliano, C.Sciarretta, G.Bianco, F.Vespe, Earth
    Orientation Parameters measured by Space Geodesy Techniques, In:
    Towards an Integrated Global Geodetic Observing System (IGGOS), IAG
    Symposia (120) 177-179, 2000

3.  G. Bianco, R. Devoti, M. Fermi, C. Ferraro, R. Lanotte, V.
    Luceri, A. Nardi, R. Pacione, P. Rutigliano, C. Sciarretta and F.
    Vespe, Investigation on the combination of space geodetic
    techniques, J. Geodyn. 30, 337-353, 2000.

4.  R. Devoti, V. Luceri, C. Sciarretta, G. Bianco, G. Di Donato, L.L.A.
    Vermeersen and R. Sabadini, The SLR secular gravity variations and
    their impact on the inference of mantle rheology and lithospheric
    thickness, Geophys. Res. Lett., 28(5), 855-858, 2001.

5.  B. Bianco, M. Chersich, R. Devoti, V. Luceri, M. Selden,
    Measurements of LAGEOS-2 rotation by Satellite Laser Ranging
    observations, Geophys. Res. Lett., 2001, in press

Main points of contact:

Dr. Giuseppe Bianco Dr. Vincenza Luceri

Agenzia Spaziale Italiana, ASI/CGS Telespazio SpA, ASI/CGS

P.O. Box ADP, 75100 Matera -- Italy P.O. Box ADP, 75100 Matera - Italy

tel: +39-0835-377209 tel: +39-0835-377231

fax: +39-0835-339005 fax: +39-0835-334951

e-mail: <giuseppe.bianco@asi.it> e-mail: <cinzia.luceri@asi.it>