What Is the HYG Catalog?
The data source of every star we sell: an open database merging three real catalogs.
HYG (Hipparcos–Gliese–Yale) merges three real astronomical catalogs into one searchable database of about 120,000 stars with traceable J2000 coordinates, magnitudes, distances and spectral types. Our star library covers 107,838 of them across all 88 constellations.
The three sources
- Hipparcos
- ESA satellite mission — precise positions and parallaxes
- Gliese
- Nearby-star catalog covering faint, close stars
- Yale Bright Star
- Bright-star list — the famous naked-eye stars
How we use it
- Version
- HYG Database v4.1, epoch J2000.0
- Our library
- 107,838 stars · all 88 constellations
- Data page
- see /our-data for the full account and limits
Positions, distances and spectral types come from HYG; brightness and color columns are cross-checked against Gaia (that is where the gaia_source_id on star pages comes from). The catalog IDs, coordinates and data printed on your certificate are not marketing — they are raw records you can verify in any astronomy app.
The honest boundary
HYG reorganizes public research data; we did not “discover” the stars. Magnitudes and distances pass through several data-processing steps, so an individual star may differ slightly from the newest scientific releases (details on the data page). What we guarantee: every star really exists, is traceable, and is verifiable.