Observing Gaia from Earth to improve its star maps

ESA – Gaia Mission patch.

2 May 2019

While ESA�s Gaia mission has been surveying more than one billion stars from space, astronomers have been regularly monitoring the satellite�s position in the sky with telescopes across the world, including the European Southern Observatory in Chile, to further refine Gaia�s orbit and ultimately improve the accuracy of its stellar census.

One year ago, the Gaia mission released its much-awaited second set of data, which included high-precision measurements � positions, distance indicators and proper motions � of more than one billion stars in our Milky Way galaxy.

Gaia among the stars

The catalogue, based on less than two years of observations and almost four years of data processing and analysis by a collaboration of about 450 scientists and software engineers, has enabled transformational studies in many fields of astronomy, generating more than 1000 scientific publications in the past twelve months.

Meanwhile in space, Gaia keeps scanning the sky and gathering data that is being crunched for future releases to achieve even higher precision on the position and motion of stars and enable ever deeper and more detailed studies into our place in the cosmos. But to reach the accuracy expected for Gaia�s final catalogue, it is crucial to pinpoint the position and motion of the satellite from Earth.

To this aim, the flight dynamics experts at ESA�s operations centre make use of a combination of techniques, from traditional radio tracking and ranging to simultaneous observing using two radio antennas � the so-called delta-DOR method.