Pinpointing Gaia to Map the Milky Way
Pinpointing Gaia to Map the Milky Way (Annotated)
Surveying the skies
The Gaia Spacecraft
Gaia’s View of the Milky Way
Videos
ESOcast 200 Light: ESO helps map the Galaxy
Animation of Gaia's Orbit
ESO’s VST helps determine the spacecraft’s orbit to enable the most accurate map ever of more than a billion stars
This image, a composite of several observations captured by ESO’s VLT Survey Telescope (VST), shows the ESA spacecraft Gaia as a faint trail of dots across the lower half of the star-filled field of view. These observations were taken as part of an ongoing collaborative effort to measure Gaia’s orbit and improve the accuracy of its unprecedented star map.
This image, a composite of several observations captured by ESO’s VLT Survey Telescope (VST), shows the ESA spacecraft Gaia as a faint trail of dots across the lower half of the star-filled field of view. These observations were taken as part of an ongoing collaborative effort to measure Gaia’s orbit and improve the accuracy of its unprecedented star map.
Gaia, operated by the European Space Agency (ESA),
surveys the sky from orbit to create the largest, most precise,
three-dimensional map of our Galaxy. One year ago, the Gaia mission
produced its much-awaited second data release, which included
high-precision measurements — positions, distance and proper motions
— of more than one billion stars in our Milky Way galaxy. This
catalogue has enabled transformational studies in many fields of
astronomy, addressing the structure, origin and evolution the Milky Way
and generating more than 1700 scientific publications since its launch
in 2013.
In order to reach the accuracy necessary for Gaia’s sky
maps, it is crucial to pinpoint the position of the spacecraft from
Earth. Therefore, while Gaia scans the sky, gathering data for its
stellar census, astronomers regularly monitor its position using a
global network of optical telescopes, including the VST at ESO’s Paranal Observatory [1]. The VST is currently the largest survey telescope observing the sky in
visible light, and records Gaia’s position in the sky every second night
throughout the year.
“Gaia observations require a special observing procedure,” explained Monika Petr-Gotzens, who has coordinated the execution of ESO’s observations of Gaia since 2013. “The
spacecraft is what we call a ‘moving target’, as it is moving quickly
relative to background stars — tracking Gaia is quite the challenge!”
“The VST is the perfect tool for picking out the motion of Gaia,” elaborated Ferdinando Patat, head of the ESO’s Observing Programmes Office. “Using
one of ESO’s first-rate ground-based facilities to bolster cutting-edge
space observations is a fine example of scientific cooperation.”
“This is an exciting ground-space collaboration, using
one of ESO’s world-class telescopes to anchor the trailblazing
observations of ESA’s billion star surveyor,” commented Timo Prusti, Gaia project scientist at ESA.
The VST observations are used by ESA’s flight dynamics
experts to track Gaia and refine the knowledge of the spacecraft’s
orbit. Painstaking calibration is required to transform the
observations, in which Gaia is just a speck of light among the bright
stars, into meaningful orbital information. Data from Gaia’s second
release was used to identify each of the stars in the field of view, and
allowed the position of the spacecraft to be calculated with
astonishing precision — up to 20 milliarcseconds.
“This is a challenging process: we are using Gaia’s
measurements of the stars to calibrate the position of the Gaia
spacecraft and ultimately improve its measurements of the stars,” explains Timo Prusti
“After careful and lengthy data processing, we have now
achieved the accuracy required for the ground-based observations of
Gaia to be implemented as part of the orbit determination,” says
Martin Altmann, lead of the Ground Based Optical Tracking (GBOT)
campaign at the Centre for Astronomy of Heidelberg University, Germany.
The GBOT information will be used to improve our knowledge
of Gaia’s orbit not only in observations to come, but also for all the
data that have been gathered from Earth in the previous years, leading
to improvements in the data products that will be included in future
releases.
Notes
[1] This collaboration between ESO and ESA is just one of several cooperative projects which have benefitted from the expertise of both organisations in progressing astronomy and astrophysics. On 20 August 2015, the ESA and ESO Directors General signed a cooperation agreement to facilitate synergy through projects such as these.
More Information
In order to foster exchanges between astrophysics-related spaceborne missions and ground-based facilities, as well as between their respective communities, ESA and ESO are joining forces to organise a series of international astronomy meetings. The first ESA-ESO joint workshop will take place in November 2019 at ESO and a call for proposals for the second workshop, to take place in 2020 at ESA, is currently open.
ESO is the foremost intergovernmental astronomy
organisation in Europe and the world’s most productive ground-based
astronomical observatory by far. It has 16 Member States: Austria,
Belgium, the Czech Republic, Denmark, France, Finland, Germany, Ireland,
Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland
and the United Kingdom, along with the host state of Chile and with
Australia as a Strategic Partner. ESO carries out an ambitious programme
focused on the design, construction and operation of powerful
ground-based observing facilities enabling astronomers to make important
scientific discoveries. ESO also plays a leading role in promoting and
organising cooperation in astronomical research. ESO operates three
unique world-class observing sites in Chile: La Silla, Paranal and
Chajnantor. At Paranal, ESO operates the Very Large Telescope and its
world-leading Very Large Telescope Interferometer as well as two survey
telescopes, VISTA working in the infrared and the visible-light VLT
Survey Telescope. Also at Paranal ESO will host and operate the
Cherenkov Telescope Array South, the world’s largest and most sensitive
gamma-ray observatory.
ESO is also a major partner in two facilities on
Chajnantor, APEX and ALMA, the largest astronomical project in
existence. And on Cerro Armazones, close to Paranal, ESO is building the
39-metre Extremely Large Telescope, the ELT, which will become “the
world’s biggest eye on the sky”.
The European Space Agency (ESA) is Europe’s gateway to
space. Its mission is to shape the development of Europe’s space
capability and ensure that investment in space continues to deliver
benefits to the citizens of Europe and the world.
ESA is an international organisation with 22 Member States.
By coordinating the financial and intellectual resources of its
members, it can undertake programmes and activities far beyond the scope
of any single European country.
ESA's Gaia satellite was launched in 2013 to create the
most precise three-dimensional map of more than one billion stars in the
Milky Way. The mission has released two lots of data thus far: Gaia
Data Release 1 in 2016 and Gaia Data Release 2 in 2018. More releases
will follow in the coming years.
Links
Contacts
Calum Turner
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6670
Email: pio@eso.org
Links
Contacts
Calum Turner
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6670
Email: pio@eso.org
Source: ESO/News
