Sources & Credits
This map is assembled from open astronomical catalogs. This is the same data professional observatories and planetarium software are built on. Nothing here is invented; every star, line, and nebula comes from published work by people who spent careers measuring the sky. Our thanks to all of them.
The stars
Star positions, brightnesses, and names come from the HYG Database (v41), compiled by David Nash from the Hipparcos, Yale Bright Star, and Gliese catalogs and released under CC BY-SA 4.0. We draw 8,922 of its 119,626 stars: everything visible to the naked eye under a dark sky, plus every star needed to complete a constellation figure.
The constellations
The constellation lines and names are the modern skyculture from Stellarium, the open-source planetarium project, used under CC BY-SA 4.0. Thanks to Stellarium’s team. Constellation figures are a matter of convention rather than fact.
The deep sky
Galaxies, nebulae, and clusters, including the Messier objects, come from OpenNGC by Mattia Verga, © 2023 and released under CC BY-SA 4.0.
The HII regions are great glowing hydrogen clouds where stars are born. Our list comes from Stewart Sharpless’s 1959 A Catalogue of H II Regions (Astrophysical Journal Supplement Series, 4, 257), obtained through the VizieR service, with cross-identifications and modern positions from SIMBAD. Both are operated by the Centre de Données astronomiques de Strasbourg. Sharpless’s coordinates are recorded in the B1950 reference frame; we precess them to J2000 so they line up with everything else on this map.
The fainter, more diffuse nebulae come from Beverly Lynds’s 1965 Catalogue of Bright Nebulae (Astrophysical Journal Supplement Series, 12, 163), also through VizieR, and also precessed from B1950. Lynds measured these by eye from the Palomar sky survey plates and graded each one from 1 to 6 for brightness. We keep that grade but deliberately do not filter on it: a modern camera stacking hours of exposure reaches things a 1965 photographic plate could barely register, so several of the objects she marked “barely detectable” are ordinary targets today.
A very small number of targets are entered by hand, because the catalog they belong to was never published in a form a computer can read. The Propeller Nebula is the reason this exists: astrophotographers all know it as Simeis 57, but that designation appears in no machine-readable table we can point a build script at. Each hand-entered object records where every one of its values came from, and says plainly which of them are estimates.
This research has made use of the SIMBAD database, CDS, Strasbourg Astronomical Observatory, France.
This research has made use of the VizieR catalogue access tool, CDS, Strasbourg Astronomical Observatory, France.
The Milky Way
The background is Deep Star Maps 2020, made by Ernie Wright at NASA’s Scientific Visualization Studio from 1.7 billion stars measured by ESA’s Gaia mission.
NASA/Goddard Space Flight Center Scientific Visualization Studio. Gaia DR2: ESA/Gaia/DPAC.
Interface
Equipment icons are from Lucide, © Lucide Contributors, used under the ISC license. Type set in Outfit, Figtree, and IBM Plex Mono, all under the SIL Open Font License 1.1. The object-type glyphs on the map were drawn for this project.
The photographs
Every astrophotograph on this site was taken by Angela Brand. They are © Copyright Angela Brand, all rights reserved, and are not covered by the open licenses above. Please don’t reuse them without receiving full permission.
On licensing
The catalog data this map loads is available under CC BY-SA 4.0, the same license we received most of it under. The Sharpless, Lynds, and SIMBAD material is used under CDS’s terms, which allow scientific and educational use but not commercial use. This site is non-commercial by design: no ads, nothing for sale, no charge to look at the sky.