Gaia Data Release 3

achivement of five years of intense work through adversity.

Last updated on 2022-06-13 · 4min read · Gaia

Finally, after many years of hard work, we made it! the Gaia Data Release 3 (Gaia DR3) is out. GDR3 is the work of the Gaia DPAC (data processing and analysis consortium), i.e. over 400 European scientists and engineers.

We overcame unforeseen complicated challenges

Gaia DR3 was marked by a very complicated context of unforeseen events and a pandemic context. As a result, we decided to split the release and the first part of GDR3 was published as EDR3 (early DR3) in December 2020. This early release catalog contained information about 1.81 billion stars: astrometry, and integrated broad band photometry. This new part contains what the community has been waiting for eagerly: the dispersed light spectra (BP/RP) for 220 million objects, and 1 million high-resolution spectra (RVS).

The CU8 data release: the astrophysical parameters

But the second part -- Gaia DR3 -- contains much more. It contains in particular the astrophysical paramters (APs), the work I took part in with the CU8 team. CU8 comprises more than 75 scientists and engineers across 15 cells and 8 countries and their work span a large variety of tasks: for instance software development, data management, refinement of stellar atmosphere, spectroscopy, and cosmology. In Gaia DR3, CU8 provides

  • classifications for 1.6 billion sources,
  • temperatures, gravities, distances, and radii for 470 million stars using BP/RP, and for 6 million using RVS,
  • 130 million ages and masses,
  • 5 million chemical abundances,
  • 2 million chromospheric activity indices rotation velocities,
  • and extinction maps.

The details, it is all described in the three main CU8 papers

This represents of course only a (not so) brief overview of the work that CU8 undertook. CU8 led 12 of the 45 papers coming with Gaia DR3 and they had major contributions to a dozen more.

What's next?

GDR3 spans 34 months of observations taken from July 2014 to May 2017. The Gaia mission was initially planned for 5 years (until 2020) and Gaia has not stopped observing our Galaxy. We expect the mission to successfully pass the 10-year mark.

Gaia DR4 expected in ~2025 will contain all data products from the nominal 5-year mission:

  • updated astrometry: parallax and proper motions
  • all BP/RP and RVS spectra
  • New astrophysical parameters (not only updated values)
  • epoch astrometry
  • epoch photometry
  • and the raw data

And Gaia DR5 will mark the end of the mission with all 10-year+ data products.

A human adventure through storms and bad weather conditions

Gaia DR3 was an adventure in many aspects. It was a long journey, but it is a very rewarding one.

I was a postdoc (until 2021) at the MPIA and I was part of the management team of CU8. I was leading the validation of the scientific products, but I also had technical responsibilities (e.g., data model, data management, software development).

It was far from smooth sailing. We went through a lot of storms and bad weather conditions. COVID-19 had a major impact on the timeline but most importantly on the mental health of the team. We had to deal with a lot of stress and we had to deal with a lot of work. But the team found the energy to adapt to the conditions and made it through for a successful release.

I learned a lot about managing a team and how to deal with my stress and the stress of others. I discovered why all this mindfulness thing is so important. I also realized aspects of academia that I had never seen before, and not all of them are healthy in my opinion.

I may write a retrospective on the human side of the journey.