Letters of Intent for 2015

LoI 2015-214
Focus Meeting: Towards a promising harvest for Gaia


1 August 2015 to 14 August 2015


IAU GA 2015, United States


Timo Prusti (tprusti@rssd.esa.int)

Coordinating division:

Division A Fundamental Astronomy

Co-Chairs of SOC:

Timo Prusti (ESA)
Anthony Brown (Leiden University)

Chair of LOC:




Gaia status and in flight performance

Gaia science alerts results - supernovae, novae and the exotic.

The First Gaia Data: Hundred Thousand Proper Motions catalogue

Upcoming data releases: contents and tools

Results from the preparatory modelling and simulation work for the scientific exploitation of Gaia

Gaia outlook for Milky Way studies

Gaia outlook for stellar astrophysics

Gaia promise for solar system, exoplanet and extragalactic research areas

Microarcsecond astrometry as a laboratory for fundamental physics

Gaia-ESO spectroscopic survey results and synergies with other ground-based surveys

Beyond Gaia - the cosmos at the sub microarcsec scale.



Gaia is an astrometric, photometric and spectroscopic survey of the full sky. Unbiased on-board detection will ensure astrometry and photometry for all stars between magnitudes 6 and 20. This Gaia catalogue is anticipated to contain 1 billion sources. Spectroscopy will be conducted for magnitude range 6-17 to deduce radial velocities for an estimated sample of 150 million stars. In addition to the kinematic data from astrometry and radial velocities, the photometric and spectroscopic measurements can be used to classify objects and measure astrophysical parameters for stars.

Gaia is scheduled for 20 November 2013 launch. With this timing, by summer 2015 Science Alerts are released regularly and the first catalogue of positions may be available. The IAU General Assembly is right at the time when the Gaia results start to impact the fundamentals of astronomy. The IAU GA marks the start of a decade when Gaia will revolutionise our understanding of stellar astrophysics, the Milky Way and many other research topics. It is clear that the Gaia landscape, progress so far and prospects for the future, has to be presented to the General Assembly. We propose an IAU Focus Meeting to achieve this goal.

We plan a three day Focus Meeting with a specific aspect of Gaia for each day. Day 1 we plan to address the overall status of the mission. This includes a description of the operational aspects which have a scientific impact to the catalogue. Also the calibration issued tackled will be dealt with. An important aspect for the community is to get a very advanced report of the expected final accuracies Gaia can reach. Of immediate interest are details of the intermediate releases, both from the content and schedule perspectives. The description of the intermediate catalogues provides also an opportunity to present the specific tools developed in the Gaia context to help the community deal efficiently with the huge catalogue. Also all Gaia data released at that point of time will be presented. These early data are Science Alerts, which are the first Gaia releases. The Hipparcos stars proper motion catalogue is also intended as an early product. In the planning for the first intermediate data release it is anticipated to provide positions only. When these data are combined with the Hipparcos measurements 20 years earlier, it is possible to provide proper motions for the common stars. In case this first intermediate release can be made in time, then IAU GA could be a suitable forum to release the Hipparcos stars proper motion catalogue.

The second day of the Focus Meeting is devoted to science results. These span studies and models made while preparing for the Gaia data. This session would also include results from the Gaia-ESO ground-based spectroscopic survey, which at that moment has 3.5 years of data gathering and analysis completed. Furthermore the various other ground-based surveys, which have been partly motivated with the existence of the Gaia mission, will be included in the programme.

The third day of the Focus Meeting is dedicated to the specific science topics which will experience major impact by the Gaia catalogue. The status of the research areas will be summarised at that moment just before the Gaia results start to make their mark. Most of the time will be dedicated to Milky Way and stellar studies as the anticipation is that in those fields the earlier intermediate releases already will have a major impact. Furthermore outline of Gaia related topics in solar system, exoplanet and extragalactic topics will be included. Special attention will be provided to the Gaia potential in the area of fundamental physics as it links directly to the ultimate performance we can expect from Gaia.

Although the Gaia harvest is 2015 only at the beginning, we also want to devote time to the future and have a short discussion of science behind astrometry at sub microarcsec level.

IAU General Assembly
Honolulu, 3-14 August 2015

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