--- title: Star catalogue canonical_url: https://paxabyssi.com/wiki/Star_catalogue markdown_url: https://paxabyssi.com/wiki/Star_catalogue.md type: wiki-page revision_id: 32 revision_view: stable last_updated: 2026-09-27 license: CC BY-SA 4.0 license_url: https://creativecommons.org/licenses/by-sa/4.0/ science_status: - observed - sim summary: The 119,626 real stars at the heart of Pax Abyssi, built from the HYG database and corrected against Gaia DR3, Hipparcos, XHIP and the Washington Double Star Catalog, with every correction kept beside the original value. categories: - Catalogues and data - The Galaxy - Data sources aliases: - Pax Abyssi star catalogue - HYG catalogue - HYG database - 626 stars - The star catalogue - Catalogue stars infobox: type: dataset rows: 119626 image: File:Catalogue_sky_sim.png columns: 77 licence: CC BY-SA 4.0 (HYG); corrections and added columns by Pax Abyssi coordinates: "equatorial (ICRS/J2000): x toward RA 0h Dec 0, y toward RA 6h Dec 0, z toward the north celestial pole; parsecs from the Sun" completeness: about 60 percent of stars within 25 pc; under 10 percent within 100 pc proper_names: 511 age_rows_xhip: 12921 internal_file: pax_abyssi_hyg_v3.csv (the fork's own version number; built from HYG v4.1) base_catalogue: "HYG Database v4.1 (David Nash, astronexus): Hipparcos, Yale Bright Star Catalogue 5th ed., Gliese Catalogue of Nearby Stars 3rd ed." correction_sources: Gaia DR3 parallaxes; XHIP spectral types, metallicities and ages; Washington Double Star Catalog; photometric distance estimates spectral_type_rows: 116,578 (97.5 percent) rows_with_a_distance: 119,624 of 119,626 after corrections metallicity_rows_xhip: 19097 naked_eye_stars_v_le_6: 5,070, plus the Sun gaia_dr3_distances_rows: 97,962 (81.9 percent) wds_cross_matched_stars: 461 corrected_spectral_type_rows: 75529 median_gaia_parallax_uncertainty_percent: 0.58 related: - https://paxabyssi.com/wiki/Milky_Way.md - https://paxabyssi.com/wiki/Sol.md - https://paxabyssi.com/wiki/Red_dwarf.md - https://paxabyssi.com/wiki/Star_system_generation.md - https://paxabyssi.com/wiki/Stellar_classification.md - https://paxabyssi.com/wiki/White_dwarf.md --- # Star catalogue > Source: https://paxabyssi.com/wiki/Star_catalogue > > Licence: [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0/). Text by Pax Abyssi Wiki contributors; history at https://paxabyssi.com/wiki/Star_catalogue/history > > Revision 32, 27 September 2026 The **star catalogue** of [Pax Abyssi](https://paxabyssi.com/wiki/Pax_Abyssi.md) is a table of 119,626 real stars, each one a measured object with a position, a brightness and, for almost all of them, a spectral type. It began as the public HYG database, a merger of the Hipparcos, Yale Bright Star and Gliese catalogues compiled by David Nash, and has been corrected row by row against newer measurements, above all the parallaxes of ESA's Gaia mission. [1] [2] Every star in the game's night sky is a row in this table, and every correction sits in a column of its own beside the value it replaces, so the original measurement is never lost. (Image pending: A black sky scattered with stars of different brightness, a few of them faintly orange or blue-white.) *Figure 1.* Sim render. A patch of the naked-eye sky as the game draws it: every point is a catalogue row, placed by its measured right ascension and declination and scaled by its measured magnitude. ## Where the stars come from HYG is named for its three sources. [1] - **Hipparcos**, the ESA satellite that measured 118,218 stars between 1989 and 1993 and gave the first large set of accurate parallaxes, about a thousandth of an arcsecond in precision for most of them. [3] [4] A 2007 re-reduction of the raw data improved many of them. [5] - **The Yale Bright Star Catalogue**, fifth edition: the stars visible to the naked eye, with their traditional names and designations. [6] - **The Gliese Catalogue of Nearby Stars**, third edition: stars within about 25 parsecs, including many faint red dwarfs too dim for Hipparcos. [7] The current public release is HYG v4.2 (2025). The Pax Abyssi catalogue was forked from v4.1 and carries the internal file name `pax_abyssi_hyg_v3`, which is the fork's own version number rather than HYG's. Its 77 columns are HYG's own 37 (identifiers, astrometry, photometry and multiplicity) plus 40 added ones: extended Hipparcos data, bolometric luminosities, Gaia DR3 distances, photometric distance estimates, double-star cross-matches and the override columns. ## Distance from parallax A star's distance comes from its **parallax**, the small shift in its apparent position as Earth moves from one side of its orbit to the other. The parallax angle $p$ is the angle the radius of Earth's orbit subtends at the star, and the distance in parsecs is simply its reciprocal: $$ d\ [\mathrm{pc}] = \frac{1}{p\ [\mathrm{arcsec}]} = \frac{1000}{p\ [\mathrm{mas}]} $$ One parsec is about 3.26 light years. Gaia DR3 gives Proxima Centauri a parallax of 768.07 milliarcseconds (mas), so it lies 1.302 pc, or 4.25 light years, away. A star at 1,000 pc shows a parallax of only 1 mas, the width of a coin seen from about 4,000 km away. Distance turns apparent brightness into true brightness. The **distance modulus** links the apparent magnitude $m$, what we see, to the absolute magnitude $M$, how bright the star would look from 10 pc: $$ m - M = 5 \log_{10}\!\left(\frac{d}{10\ \mathrm{pc}}\right) $$ The fractional error in distance is roughly the fractional error in parallax. When the parallax is small compared with its uncertainty, the reciprocal becomes meaningless. HYG handles such stars by giving them a placeholder distance of 100,000 pc, a flag meaning "missing or dubious parallax". [8] In the inherited file, 10,225 rows, 8.5 percent of the catalogue, carried that flag, and every quantity derived from distance was wrong for them. HIP 13, an ordinary orange giant of magnitude 8.8, appeared as a star 2.6 million times as luminous as the Sun, placed twice as far away as the Large Magellanic Cloud. ## The corrections **Gaia DR3.** Gaia's third data release (2022) measured parallaxes for about 1.47 billion sources. [9] [2] The catalogue took Gaia DR3 parallaxes for 97,962 rows, 81.9 percent of it, through Gaia's own cross-match with Hipparcos. Their median uncertainty is 0.58 percent. The placeholder rows were recovered in three tiers: 9,053 from Gaia, 1,170 from a photometric estimate (the distance a star of that spectral type must have to look as faint as it does), and 2 that neither method could place. HIP 13 now sits at 415 pc, an ordinary giant about 45 times as luminous as the Sun in visible light. Gaia parallaxes carry a small systematic offset of a few hundredths of a milliarcsecond, which matters only for the most distant stars in the table. [10] **Extended Hipparcos (XHIP).** XHIP compiles spectral classifications, metallicities, ages and other data for Hipparcos stars. [11] It supplies metallicity for 19,097 rows and ages for 12,921, and it was the reference for 25,853 of the 75,529 corrected spectral types. A spectral-source column records where every type came from. **Double stars.** HYG marks very few stars as multiple. A cross-match with the Washington Double Star Catalog, the standard register of visual binaries, identified companions for 461 catalogue stars. [12] The game adds procedural companions to others to reach the binary fractions measured in surveys; those are flagged as procedural and are never presented as observations. **Spectroscopy.** For about 6,000 nearby Sun-like stars, detailed abundances and temperatures from the Hypatia Catalog take priority when the game derives a star's properties. [13] Automatic corrections can be wrong too. A 2026 audit found that one rule-based pass had demoted some famous supergiants, Rigel among them, to main-sequence dwarfs. Measured values from recent papers now override the catalogue for the named stars affected, and the override columns make such mistakes visible and reversible. ## How complete it is The catalogue is limited by brightness, and it is centred on the Sun. Near the Sun it is fairly full; farther out it holds only the bright stars. | Distance from the Sun | Catalogue rows | Reference census | | ------------------------------- | -------------- | ----------------------------------------------------------------------------- | | within 25 pc (82 light years) | about 3,100 | 5,230 stars and 701 brown dwarfs in the Fifth Catalogue of Nearby Stars [14] | | within 100 pc (326 light years) | about 23,900 | more than 300,000 stars in Gaia's Catalogue of Nearby Stars [15] [16] | So even within 25 pc the catalogue holds about 60 percent of the known stars, and within 100 pc under 10 percent. The missing ones are mostly faint red dwarfs and white dwarfs, the commonest stars in the Galaxy and the hardest to see. Beyond that, the game fills space from a model of the [Milky Way](https://paxabyssi.com/wiki/Milky_Way.md). ## Coordinates HYG gives each star Cartesian coordinates $x$, $y$, $z$ in parsecs from the Sun, in the **equatorial** frame: $+x$ toward the vernal equinox (right ascension 0h, declination 0), $+y$ toward right ascension 6h, and $+z$ toward the north celestial pole. [8] That frame is tied to Earth's spin axis, and it is tilted about 63 degrees to the plane of the Galaxy. Using the equatorial $x$-$y$ plane as if it were the Galactic plane is a tempting mistake. The procedural fill the game inherited made it, and the error was found and corrected in 2026 by rotating every row into a proper Galactic frame. ## Notable examples | Star | Catalogue value | Source of the distance | What it shows | | ------------------ | ------------------------ | ---------------------------- | --------------------------------------------------------------------------------------------------------------------------------------- | | Proxima Centauri | 1.302 pc | Gaia DR3 (768.07 ± 0.05 mas) | Gaia refines Hipparcos's 1.296 pc | | Barnard's Star | 1.828 pc | Gaia DR3 (546.98 ± 0.04 mas) | the second-nearest star system | | Sirius | 2.64 pc | Hipparcos | the brightest stars have no Gaia DR3 match here and keep their Hipparcos parallax | | Vega | 7.68 pc | Hipparcos | the same | | HIP 13 | 415 pc | Gaia DR3 | recovered from HYG's 100,000 pc placeholder | | T Coronae Borealis | 916 pc | Gaia DR3 | the recurrent nova called the Blaze Star, also recovered from the placeholder | | mu Cephei | parallax 0.12 ± 0.26 mas | Gaia DR3, unusable | a parallax smaller than its own error: inverting it gives 8,400 pc, which means nothing, so a published distance has to be used instead | > **In Pax Abyssi** > > **BUILT.** The catalogue is the game's sky. The cockpit draws the 5,070 stars at magnitude 6.0 or brighter, 390 of them named, at their measured positions, brightnesses and colours. Any of them can be clicked for a 110-field star sheet generated from its row. The galaxy map holds 119,624 catalogue stars in 32 display classes. The file is never edited by hand: every correction is a script that writes a new column. > > **Not yet.** The sky is Sol's sky everywhere: travel to another star and the constellations do not yet change, although the catalogue already carries the $x$, $y$, $z$ positions needed to redraw the sky from any viewpoint. Stars beyond the catalogue's reach come from the generated galaxy, which is in progress. ## Credits and licences The catalogue is derived from the **HYG Database** (David Nash, astronexus), licensed under Creative Commons Attribution-ShareAlike 4.0; tables and data exports derived from it are shared under the same licence. [1] This work has made use of data from the European Space Agency (ESA) mission Gaia (), processed by the Gaia Data Processing and Analysis Consortium (DPAC, ). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. [17] [2] It also uses the Hipparcos Catalogue (ESA), the Extended Hipparcos Compilation, the Washington Double Star Catalog (US Naval Observatory) and the Hypatia Catalog. [4] [11] [12] [13] ## See also - [Milky Way](https://paxabyssi.com/wiki/Milky_Way.md), the model that fills space beyond the catalogue - [Sol](https://paxabyssi.com/wiki/Sol.md), the one star whose sky the game draws today - [Stellar classification](https://paxabyssi.com/wiki/Stellar_classification.md) - [Red dwarf](https://paxabyssi.com/wiki/Red_dwarf.md) and [White dwarf](https://paxabyssi.com/wiki/White_dwarf.md), the stars the catalogue misses most - [Star system generation](https://paxabyssi.com/wiki/Star_system_generation.md), what the game builds around a catalogue star - [Science in Pax Abyssi](https://paxabyssi.com/wiki/Science_in_Pax_Abyssi.md) ## References 1. Nash, D. (2025). The HYG Database. astronexus.com. 2. Gaia Collaboration, Vallenari, A. and et al. (2023). Gaia Data Release 3: Summary of the content and survey properties. Astronomy & Astrophysics 674, A1. 3. European Space Agency. Hipparcos. ESA Cosmos. 4. Perryman, M. A. C. and et al. (1997). The HIPPARCOS Catalogue. Astronomy & Astrophysics 323, L49-L52. 5. van Leeuwen, F. (2007). Validation of the new Hipparcos reduction. Astronomy & Astrophysics 474, 653-664. 6. Hoffleit, D. and Warren, W. H. (1991). Bright Star Catalogue, 5th Revised Ed. VizieR On-line Data Catalog V/50. 7. Gliese, W. and Jahreiss, H. (1991). Nearby Stars, Preliminary 3rd Version. VizieR On-line Data Catalog V/70A. 8. Nash, D.. HYG Database: details and field definitions. astronexus.com. 9. European Space Agency. Gaia Data Release 3 (Gaia DR3). ESA Cosmos. 10. Lindegren, L. and et al. (2021). Gaia Early Data Release 3: Parallax bias versus magnitude, colour, and position. Astronomy & Astrophysics 649, A4. 11. Anderson, E. and Francis, C. (2012). XHIP: An extended Hipparcos compilation. Astronomy Letters 38, 331-346. 12. Mason, B. D. and et al. (2001). The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog. The Astronomical Journal 122, 3466-3471. 13. Hinkel, N. R. and et al. (2014). Stellar Abundances in the Solar Neighborhood: The Hypatia Catalog. The Astronomical Journal 148, 54. 14. Golovin, A. et al. (2023). The Fifth Catalogue of Nearby Stars (CNS5). Astronomy & Astrophysics 670, A19. 15. Gaia Collaboration et al. (2021). Gaia Early Data Release 3: The Gaia Catalogue of Nearby Stars. Astronomy & Astrophysics 649, A6. 16. European Space Agency. Gaia EDR3: the Gaia Catalogue of Nearby Stars. ESA Cosmos. 17. Gaia Collaboration, Prusti, T. and et al. (2016). The Gaia mission. Astronomy & Astrophysics 595, A1. ## Infobox (dataset) | Field | Value | | --- | --- | | Rows | 119626 | | Image | File:Catalogue_sky_sim.png | | Columns | 77 | | Licence | CC BY-SA 4.0 (HYG); corrections and added columns by Pax Abyssi | | Coordinates | equatorial (ICRS/J2000): x toward RA 0h Dec 0, y toward RA 6h Dec 0, z toward the north celestial pole; parsecs from the Sun | | Completeness | about 60 percent of stars within 25 pc; under 10 percent within 100 pc | | Proper names | 511 | | Age rows xhip | 12921 | | Internal file | pax_abyssi_hyg_v3.csv (the fork's own version number; built from HYG v4.1) | | Base catalogue | HYG Database v4.1 (David Nash, astronexus): Hipparcos, Yale Bright Star Catalogue 5th ed., Gliese Catalogue of Nearby Stars 3rd ed. | | Correction sources | Gaia DR3 parallaxes; XHIP spectral types, metallicities and ages; Washington Double Star Catalog; photometric distance estimates | | Spectral type rows | 116,578 (97.5 percent) | | Rows with a distance | 119,624 of 119,626 after corrections | | Metallicity rows xhip | 19097 | | Naked eye stars v le 6 | 5,070, plus the Sun | | Gaia dr3 distances rows | 97,962 (81.9 percent) | | Wds cross matched stars | 461 | | Corrected spectral type rows | 75529 | | Median gaia parallax uncertainty percent | 0.58 | ## Related pages - [Milky Way](https://paxabyssi.com/wiki/Milky_Way.md): The barred spiral galaxy that contains the Sun, some 100 to 400 billion stars in a disk about 30 kiloparsecs across, and the setting of Pax Abyssi. - [Sol](https://paxabyssi.com/wiki/Sol.md): The Sun and its planetary system, the one star system in Pax Abyssi built entirely from measurement, with nine planets including Pluto and 28 moons on orbits fitted to JPL ephemerides. - [Red dwarf](https://paxabyssi.com/wiki/Red_dwarf.md): A small, cool, faint main-sequence star of spectral class M, between about 8% and 60% of the Sun's mass. Red dwarfs are about three quarters of all stars, live for trillions of years, flare violently when young, and host many of the nearest known rocky planets. - [Star system generation](https://paxabyssi.com/wiki/Star_system_generation.md): How Pax Abyssi builds the planets, moons, rings and belts of every star system except our own, from a star's catalogue row, published occurrence rates and planetary physics, the same way every time. - [Stellar classification](https://paxabyssi.com/wiki/Stellar_classification.md): How astronomers sort stars by their spectra. A letter (O, B, A, F, G, K, M, and L, T, Y for the coolest objects) and a number give the surface temperature; a Roman numeral gives the size and brightness. The Sun is a G2V star. - [White dwarf](https://paxabyssi.com/wiki/White_dwarf.md): The exposed core of a dead Sun-like star, about as massive as the Sun but the size of Earth, held up by the quantum pressure of its electrons and cooling for billions of years. Categories: [Catalogues and data](https://paxabyssi.com/wiki/Category:Catalogues_and_data.md), [The Galaxy](https://paxabyssi.com/wiki/Category:The_Galaxy.md), [Data sources](https://paxabyssi.com/wiki/Category:Data_sources.md)