TheGalaxyDB is a living galactic encyclopedia assembled from five public astronomical datasets: SDSS DR17, HyperLEDA, HECATE, PGC2003, and Mangrove. 22.4 million galaxies, each carrying whatever the union of those sources can provide morphology, redshift, distance, stellar mass, and star formation rate. Every galaxy is rendered live in your browser using GLEN, the Galaxy Engine a custom WebGL renderer that produces morphologically-accurate galaxy visualizations with physically-derived structure.
GLEN stands for Galactic Layer & Environment Navigator. Where STEN (the Star Engine, powering TheStarDB) renders individual stellar objects, GLEN operates at galactic scale. It characterises a galaxy's morphological class, inclination, bar strength, spiral arm winding, and integrated color, then produces a real-time rendering that reflects those measured parameters. Spiral arms tighten from Sa to Sc. Bars strengthen through SBa to SBc. Ellipticals shift from compact E0 to flattened E7. What you see in GLEN is what the data says not what an artist imagined.
Sb Spiral Galaxy · GLEN Render
Each morphological class has a dedicated shader in GLEN from tight-wound Sa spirals to E0 compact ellipticals to chaotic irregulars shaped by ancient collisions.
HyperLEDA catalogs over four million galaxies but only carries morphological T-types for roughly 60,000 of them leaving 3.94 million with no structural classification. NASA/IPAC NED indexes approximately three billion source entries, the overwhelming majority typed simply “Galaxy” with no morphology, stellar mass, or star formation rate. Nobody has filled this gap at the scale of 22 million objects with computed physical properties for all of them. Until now.
Every galaxy entry carries a classification label at the record level: SPECTROSCOPIC where T-type comes from HyperLEDA survey data, and PHOTOMETRIC where morphology is derived from WISE infrared color-morphology relations. Honest about what the data is. Always.
For galaxies with known physical parameters, GLEN applies the same derivation philosophy used for star clusters across the network. The Tully–Fisher relation (L ∝ vrot4) links a spiral galaxy's rotation velocity to its intrinsic luminosity, allowing an absolute magnitude to be derived from kinematic measurements alone. For ellipticals, the Faber–Jackson relation (L ∝ σ4) does the same using stellar velocity dispersion, and the Fundamental Plane refines this further with effective radius, reducing the scatter from ±1.5 mag to roughly ±0.3 mag. These are the galaxy-scale equivalents of the distance modulus chain applied to star clusters on TheStarDB: a physically motivated empirical calibration, fitted on objects with measured magnitudes, then applied to fill in properties for objects where the measurement was missing. The 1.1 million SDSS spectroscopic velocity dispersions in the GLEN catalog are the raw material for Faber–Jackson derivations at scale. Where we have applied a derived estimate rather than a measured value, it is flagged PHOTOMETRIC. The formal discipline covering all of this is galaxy scaling relations a well-established sub-field of extragalactic astrophysics. The data existed. The equations are textbook. The application at this scale was not done before.
GLEN derives physical properties for galaxies using established empirical scaling relations from extragalactic astrophysics. The chains below are the exact methods applied. Where a value is derived rather than directly observed, it is labeled PHOTOMETRIC in the catalog.
For spiral galaxies with measured rotation velocities from 21 cm HI observations or optical spectroscopy, the Tully-Fisher relation links rotation speed to total luminosity. The steep power law (4th power) means a factor of 2 in rotation velocity corresponds to a factor of 16 in luminosity, making this a precise distance and luminosity indicator for well-inclined disk galaxies.
For elliptical galaxies, stellar velocity dispersion σ serves the same role as rotation velocity for spirals. The GLEN catalog contains 1.1 million SDSS DR17 spectroscopic velocity dispersions, making this the raw material for Faber-Jackson derivations at a scale no prior public catalog has reached. Each derived value is flagged PHOTOMETRIC.
The Fundamental Plane is a tighter constraint than Faber-Jackson alone, adding effective radius Re and mean surface brightness Ie as a third axis. For galaxies where all three quantities are available, this reduces scatter from ±1.5 mag to ±0.3 mag, a fivefold improvement. GLEN applies the Fundamental Plane wherever the supporting photometry exists, falling back to Faber-Jackson otherwise.
HyperLEDA provides morphological T-types for only ~52,000 of the 22.4 million galaxies in the GLEN catalog. For the remaining 21.9 million, a color-morphology calibration assigns a T-type estimate: bluer integrated colors indicate young stellar populations characteristic of late-type spirals; redder colors indicate the older stellar populations of ellipticals and lenticulars. This is the photometric proxy for morphology in the absence of resolved imaging. Every such assignment is labeled PHOTOMETRIC and flagged for later verification against deeper surveys.
GLEN renders each galaxy class with a dedicated GLSL pipeline. Not flat images. Not sprites. Real-time WebGL shaders that respond to the galaxy's Hubble type, bar strength, arm pitch angle, and inclination. All computed on your GPU, per frame.
Every galaxy carries redshift, distance, morphology, stellar mass, and SFR where available. The TheGalaxyDB API exposes the full 22.4M-entry dataset for programmatic access REST-first, JSON everywhere, rate limits that scale with your plan.
TheGalaxyDB and TheStarDB share the same sanctum API backend. Together they form the astronomical database arm of the Preservation Network the only platform with 16M+ stars and 22M+ galaxies under one publicly queryable roof.
Browse 22.4 million galaxies by morphology, distance, and redshift or open the GLEN explorer and render any galactic type live in your browser.