Gaia is ESA’s latest space astrometry mission and is surveying the skies to create the most accurate map of stars in our Galaxy.
I am involved in the Gaia mission at several levels. As part of the Gaia team, I contribute to making the satellite observe the brightest stars in the sky, something the mission was not initially designed to do. As a member of the Gaia Data Processing and Analysis Consortium (DPAC), I contribute to validating and finalising the Gaia exoplanet orbit fitting pipeline. In the past, I used the Gaia catalogs to optimise the science operations of the Hubble and James Webb Space Telescopes, e.g. for distortion and focal plane geometric calibrations.
For my research, I use the released Gaia data to study exoplanets, brown dwarfs and the motions of Local Group galaxies.

Gaia observations of naked-eye stars

The Gaia survey had a nominal magnitude range of G = 6.0 – 20.0. The stars with G < 6.0, i.e. those visible to the unaided human eye, would thus not be observed by Gaia. As Research Fellow at ESAC in Madrid, Spain, which hosts the Gaia Science Operations Centre, I acquired in-depth knowledge of the mission and had the opportunity to make major contributions to an effort that resulted in effectively removing the bright limit for Gaia astrometry observations. Consequently, the data for about 5000 out of 6000 very bright stars that otherwise would have been lost were included in the second Gaia data release (DR2), representing a significant gain for the Gaia science of nearby and bright stars. However, the data quality is deteriorated compared to the nominal magnitude range and additional characterisation is required.

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Gaia image of a very bright star captured in the special imaging mode. As expected, the core is heavily saturated. Yet scientifically useful information can be extracted. From  Sahlmann et al. 2016.

Rotation of the Large Magellanic Cloud

On the day of Gaia Data Release 1 (DR1), 14 September 2016, Roeland van der Marel (STScI) and I used the Gaia DR1 proper motions of Hipparcos stars in the Large and Small Magellanic Cloud to analyse their proper motions and rotations. We submitted the resulting paper to ApJ Letters the same day. The figure below illustrates the rotation of the Large Magellanic Cloud.