SATLASOptical · Space
Gaia
EndedEnd of observations 15 January 2025, after starting 19 December 2013.
Science observations ended 15 January 2025 and the spacecraft was passivated on 27 March 2025. DR4, from 66 months of data, is due on 2 December 2026.
Two telescopes separated by a 106.5° basic angle shared one focal plane of 106 CCDsCCDCharge-coupled device: a silicon pixel array that stores photo-electrons and shifts them to a readout amplifier. The workhorse optical detector; in X-rays, each photon's charge also measures its energy., scanning the sky continuously as the spacecraft spun every six hours. A global astrometricastrometryMeasuring positions and their changes on the sky: parallax, proper motion and orbital motion. Gaia reaches tens of µas for bright stars. solution gives positions, parallaxesparallaxThe apparent annual shift of a nearby star as Earth orbits the Sun. A parallax of 1″ means a distance of 1 parsec (3.26 light years); distance in pc is 1/parallax in arcseconds. and proper motionsproper motionA star's angular motion across the sky, in mas per year, from its velocity transverse to our line of sight. to tens of microarcsecondsarcsecond1/3600 of a degree (″). A milliarcsecond (mas) is 10⁻³″ and a microarcsecond (µas) 10⁻⁶″. Atmospheric seeing limits ground telescopes to about 0.5–1″ without adaptive optics. for bright stars, with G, BP/RP and RVS photometryphotometryMeasuring the flux of a source in a passband. Aperture photometry sums pixels inside a region; PSF photometry fits the point-spread function; forced photometry measures at a position fixed in advance, whether or not a source is detected there. and spectroscopy, for 1.8 billion sources in DR3. Since 2022 Gaia-CRF3 has been the IAU's fundamental realisation of the ICRSequatorial coordinatesThe standard celestial frame, aligned with Earth's rotation axis and realised today as the International Celestial Reference System (ICRS). Positions are given as right ascension and declination. at optical wavelengths.
- Operator
- ESA
- Orbit
- Sun–Earth L2
- Aperture
- 2 telescopes, 1.45 × 0.5 m mirrors
- Passband
- 330 nm – 1050 nm
- Launch
- 19 December 2013
- End of observations
- 15 January 2025
Passband
Sky coverage
A scanning law swept great circles while the spin axis precessed around the Sun direction every 63 days, covering the whole sky about every six months; sources averaged around 70 focal-plane crossings in the first five years.
Data products
Gaia does not release images. The Data Processing and Analysis Consortium (DPAC) processes the whole mission through one global astrometric solution with photometric and spectroscopic calibrationscalibrationRemoving instrument signatures and putting data in physical units: subtracting bias and dark current, dividing by the flat field (pixel-to-pixel sensitivity), correcting non-linearity and fitting the astrometric solution. Reference files hold these calibrations and are updated as the instrument is understood., and publishes the results as versioned data releasesdata releaseA versioned, documented publication of a survey's processed data (DR1, DR2…). Later releases usually reprocess everything with improved calibration, so their values supersede, rather than add to, earlier ones.. Each release reprocesses everything over a longer time baselinebaselineThe separation between two antennas of an interferometer, projected onto the plane perpendicular to the source. Long baselines give fine resolution; short ones recover extended emission., so DR3 values supersede DR2 values rather than adding to them.
Where to start
1Positions, parallaxes, proper motions and photometry
2Stellar temperatures, distances and extinctions
3Variability and light curves
From detector to catalogueAbout data levels
| 1RawTelemetry | 2CalibratedIntermediate data | 3MeasuredData release tables | 4CombinedDerived catalogues | |
|---|---|---|---|---|
| Archive products | ||||
| Low latency | Searched as calibrated data arrive, ahead of the archive products Transient alerts | |||
Starting point, listed aboveContributed: made outside the mission pipelineSelect a product for its full entry
All products
RawTelemetry
Raw CCD windows
Detector readout
Not public
Small windows read out around each detected source as it crosses the focal plane.
CalibratedIntermediate data
Per-transit measurements
Time series
Public access: From DR4 (planned for 2 December 2026)
Individual crossing times, fluxes and spectra used inside the solution. A selection becomes public with DR4 as epoch astrometry and photometry.
MeasuredData release tables
gaia_source
Archive table (ADQL)
Positions, parallaxes, proper motions, magnitudesmagnitudeA logarithmic flux scale, m = −2.5 log₁₀(F/F₀): five magnitudes is a factor of 100, and larger is fainter. The naked eye reaches about 6; single Rubin exposures reach about 24 in r. and colours. In DR3, 1.8 billion sources, 1.5 billion with parallaxes.
Epoch photometry
Time series
Brightness over time. DR3 has it for the 10.5 million sources with variability analysis; DR4 adds G, BP and RP light curveslight curveFlux of one source as a function of time. The basic product of transit searches, variable-star work and transient follow-up. per transittransitA planet passing in front of its star and blocking a fraction (R_p/R_*)² of its light, about 84 ppm for an Earth across the Sun. Repeated transits give period and radius; spectra taken during transit probe the planet's atmosphere. as its own table.
BP/RP and RVS spectra
Spectrum
Low-resolution spectra for about 220 million sources and high-resolution spectra around the calcium triplet for about a million (DR3).
CombinedDerived catalogues
Astrophysical parameters
Catalogue
Temperatures, gravities, metallicities, distances and extinctionsextinctionDimming and reddening of light by interstellar dust, strongest at short wavelengths. Severe toward the Galactic plane, where infrared and radio see through it. inferred for hundreds of millions of stars.
Non-single stars and exoplanets
Catalogue
Binary orbits from astrometry, photometry and spectroscopy; DR4 is expected to add astrometric exoplanet candidates.
Solar system objects
Catalogue
Epoch astrometry and photometry for 158,152 Solar System objects in DR3, mostly asteroids, with reflectance spectra for 60,518.
AlertsGaia Science Alerts
Transient alerts
Alert
Sudden brightenings (supernovae, microlensingmicrolensingBrightening of a background star as a foreground star passes almost in front of it and bends its light. A planet around the lens adds a short anomaly, revealing planets at several AU independent of their brightness., outbursts) published for follow-up. AlertsalertA machine-readable notice that a source has appeared, changed or been detected, issued within seconds to days so other facilities can follow up. Optical alerts reach users through brokers; high-energy, neutrino and gravitational-wave alerts through GCN. stopped when observations ended in January 2025.
Archives
Quick start
Gaia tables are queried in ADQL through the archive's TAP service.
from astroquery.gaia import Gaia
# Every star within 10 parsecs (parallax > 100 mas)
job = Gaia.launch_job_async("""
SELECT source_id, ra, dec, parallax, pmra, pmdec, phot_g_mean_mag
FROM gaiadr3.gaia_source
WHERE parallax > 100
""")
nearby = job.get_results()Key papers
Mission · 2016
The Gaia mission (opens in a new tab)Gaia Collaboration, Prusti et al., A&A 595, A1
The spacecraft, payload, scanning law and the processing consortium (DPAC); the paper every Gaia user cites.
Data · 2023
Gaia Data Release 3: Summary of the content and survey properties (opens in a new tab)Gaia Collaboration, Vallenari et al., A&A 674, A1
What DR3 contains, how it was processed and its known limitations; read before using any DR3 table.
Pipeline · 2021
Gaia Early Data Release 3: The astrometric solution (opens in a new tab)Lindegren et al., A&A 649, A2
The astrometric solution behind DR3's positions, parallaxes and proper motions, which DR3 reuses from EDR3.
Pipeline · 2021
Gaia Early Data Release 3: Photometric content and validation (opens in a new tab)Riello et al., A&A 649, A3
G, BP and RP photometry, its calibration and the corrections users are expected to apply; also reused in DR3.
Pipeline · 2023
Gaia Data Release 3: Processing and validation of BP/RP low-resolution spectral data (opens in a new tab)De Angeli et al., A&A 674, A2
How the XP spectra are calibrated and represented as basis-function coefficients.
Data · 2018
Gaia Data Release 2: Summary of the contents and survey properties (opens in a new tab)Gaia Collaboration, Brown et al., A&A 616, A1
The first release with parallaxes and proper motions for over a billion sources; much published work is on DR2.
Data · 2021
Estimating Distances from Parallaxes. V. Geometric and Photogeometric Distances to 1.47 Billion Stars in Gaia Early Data Release 3 (opens in a new tab)Bailer-Jones et al., AJ 161, 147
The standard distance catalogue, used instead of inverting parallaxes.
Result · 2018
The merger that led to the formation of the Milky Way's inner stellar halo and thick disk (opens in a new tab)Helmi et al., Nature 563, 85
Gaia-Enceladus, found in DR2 kinematics.
Result · 2024
Discovery of a dormant 33 solar-mass black hole in pre-release Gaia astrometry (opens in a new tab)Gaia Collaboration, Panuzzo et al., A&A 686, L2
Gaia BH3, published from DR4 validation data ahead of the release.
In the literature
The star behind the TESS microlensing planet
The Gaia23bra paper takes its source star's position and brightness from Gaia DR3 (source 5252141822116891648) and its light curve from Gaia Science Alerts: two different Gaia products from two different stages.
Science cases
Sources
Verified 15 November 2026.
- Gaia at ESA (opens in a new tab)
- Gaia news 2026 (opens in a new tab)
- Gaia scanning law (opens in a new tab)
- Gaia payload module (opens in a new tab)
- Gaia DR3 contents (opens in a new tab)
- Gaia DR4 contents (opens in a new tab)
- Gaia-CRF3 (Gaia Collaboration 2022) (opens in a new tab)
- Gaia mission paper (2016) (opens in a new tab)
Other optical facilities: Hubble, SDSS, Kepler / K2, ZTF, TESS, CHEOPS, DESI, Pandora