Further information

Virtual Observatory

The virtual Observatory (VO) allows accessing data from different data centers and supplies tools to analyze them. This is possible thanks to standards that are defined by the Virtual Observatory Alliance (IVOA). Those are continuously updated to fit the user needs. The basic objective of the VO is to provide users an easy way to access a collection of heterogeneous data through Internet and user-friendly tools to interpret and understand them. In order to benefit from existing tools, datasets need to be supplied in VOTable format.

The VOTable format is based on XML (Extensible Markup Language) - it is consequently defined by its XML-schema. This format is self-descriptive and can be used to define unambiguously the data that it contains (see the footnote).

ITRF solutions in VOTable

ITRF data are supplied here in VOTable format :

We also provide two stylesheets XSLT 'Extensible Stylesheet Language – Transformations' for transforming the VOTable and better visualize its content:

nice_css.xsl. Visualize the VOTable ITRF2005.XML with that stylesheet (XSLT 1.0).
vot2ssc.xslt. If applied to ITRF2005.XML, this stylesheet transforms the file to a slightly modified version of the SSC format that has been used to provide ITRF solutions in the past : xslt_transform.txt. This transformation can not be realized without an Internet navigator compatible with XSLT 2.0.

Related web sites

http://hpiers.obspm.fr/icrs-pc/. ICRFs solutions are already available in VOTable format.
http://ivsopar.obspm.fr/vo. OPAR (one of the IVS analysis centers) provides their products in VOTable.

Footnote: 'Unified Content Descriptors' (UCD) define unambiguously a physical quantity. A working group has started to propose all the UCDs needed for geodesy which allows an unambiguous broadcasting of all geodetic datasets. Thus, geodetic data can be integrated easily in the Virtual Observatory. Draft of the UCDs to be used in geodesy has been proposed by the working group OV-Gaff.