Ephemerides

The astrometric observation of the solar system bodies is a key point to improve our knowledge of their dynamical and physical characteritics and to elaborate the theories of their motion. The IMCCE hosts numerous services of ephemeris computation and databases to prepare, to collect and to analyze such observations.

Ephemeris:

• General ephemeris of the solar system bodies position
• General ephemeris of naturals satellites position
• Ephemeris for physical observation of the solar system bodies

Databases:

• Natural Satellites Data Center (NSDC)
• Cometary Notes

Support to observers:

• International observational campaigns of natural satellites
• Solar System Object Transient Event Predictions (ssoTEP, prototype)

These services are completed with VO-compliant Web services and knowledge databases dedicated to the solar system objects.

Astrometry

The Fundamental Astronomy astrometry portal gives access to services and products which concern the monitoring of quasar coordinates: IVS-OPAR as described below.

Geodynamics

The Geodynamics portal gives access to services and products which concern the Earth’s rotation and Space Astrogeodesy, under the auspice of the International VLBI Service for Geodesy and Astrometry (IVS) and the International Earth Rotation and Reference Systems Service (IERS).

Accurate knowledge of the Earth orientation is needed for a variety of high-precision, civilian or military applications including positioning, navigation, communications, and time-keeping. In addition, EOP variations provide subtle information on the Earth’s interior (mantle anelasticity, rotation of the core and of the inner core), the interaction of the solid Earth with atmosphere, oceans and continental water (loading and deformation processes) and the response of the Earth to various natural events like earthquakes or large-scale climatic events.

The monitoring and modeling of the Earth’s orientation, are among the main missions of the SYRTE department. These activities are supported by two international services: IVS-OPAR and IERS EOP-PC as described below.

Quasars

VLBI (Very Long Baseline Interferometry) observing program proposes a regular monitoring of quasar coordinates, a relevant product for both astrometry and studying physical and dynamical properties of these mysterious objects. These activities are supported by the International VLBI Service for Geodesy and Astrometry (IVS). The SYRTE hosts one component of this service:

IVS OPAR
the Parisian IVS analysis center (head: Anne-Marie Gontier), in charge of the analysis of very long baseline radio interferometry (VLBI) observations, of the production of VLBI-derived Earth orientation parameters (EOP) time series, station position and velocity and radio source coordinate catalogues, and time series of station and radio source coordinates.

The huge and increasing number of quasars reckoned from various sky surveys leads to a large quantity of data which brings various and inhomogeneous information in the fields of astrometry, photometry, radioastronomy and spectroscopy. A compilation of various quasar catalogues, called Large Quasar Astrometric Catalogue (LQAC), is conducted at the SYRTE departement of Paris Observatory. The LAQC contains 113 666 quasars and gives equatorial coordinates, multiband photometry, radio fluxes, redshift, luminosity distances and absolute magnitudes for each of them. The LQAC in ASCII and VOtable format, together with all annexe information will be available in a near future at the web site of the International Celestial Reference System Product Center.

Reference Systems

The Reference Systems portal gives access to services and products which concern the Earth’s orientation and the Celestial Reference Systems, under the auspice of the International Earth Rotation and Reference Systems Service (IERS).

The monitoring and modeling of the Earth’s orientation, the realization and the maintenance of reference systems are among the main missions of the IERS. The SYRTE hosts two components of this service:

IERS EOP-PC
the IERS product center for EOP (head: Daniel Gambis), collecting EOP series derived from various space and geodetic technics (GNSS, VLBI, DORIS, Laser or optical), computing the international reference combined series and disseminating them through the wordlwide geodetic and astronomical community. This service offers a customized access to all operational EOP series either by a form or by a web service. It also proposes some tools for using meteorologic and oceanic data from climatic data centers to better understand and directly observe their impact on the Earth’s rotation.

Products (not yet available in VOTable format):

• Synopsis and analysis tools of all operational EOP series by technique
• C01 combined series (at 0.05-yr interval since 1846)
• C04 combined series (daily values since 1962)
• Web service under DOS and Linux

IERS ICRS-PC
the IERS product center for the international celestial reference system (ICRS, head: Jean Souchay, in collaboration with the USNO). This component participates in the elaboration and the maintenance of the international celestial reference frame (ICRF) by VLBI, and its tying to other wavelengths and to the dynamical reference system. The team also provides information on the physical and dynamical characteristics of the ICRF objects and is connected to the CDS.

Products:

• Reference catalogues:
  • ICRF - at the CDS
  • ICRF Ext.1
  • ICRF Ext.2 - at the CDS
• Informations on radio sources