The arrival of the Gaia astrometric star catalogue
will change completely the
astrometric accuracy of new observations. More, it will also allow to re-reduce old
observations with the Gaia accuracy. At the present time, we have catalogues of
a sufficient accuracy to start the new reductions. Our first purpose is to select old
observational data of selected objects of the Solar System worth to be reanalyzed.
Preliminary works have shown the interest of this task. Old observations such as photographic
plates contain valuable unused information concerning especially the moving objects
of the Solar System. We are able to "observe in the past" these moving objects,
increasing the ability to understand their dynamics.
The large amount of possible old data to be
studied makes necessary to start
now the selection and the digitizing criteria of old plates.
This workshop is dedicated to this topic.