Data & licence

Star catalogue

Celeris uses an adapted catalogue from two sources: the HYG database by Astronexus for the stars, OpenNGC for the deep-sky objects. Both are under CC BY-SA 4.0, and so is this catalogue.

stars.json.gz 443 KB gzip · 1.3 MB unpacked · 9,030 entries · JSON · CC BY-SA 4.0

Download the catalogue

What is in it

The file is a gzip-compressed JSON array of 9,030 objects:

8,920 stars from the HYG database v4.1, filtered by magnitude
110 deep-sky objects — the Messier objects, taken from OpenNGC

Fields

Field	Type	Meaning
`id`	String	Deterministic UUID, see below
`name`	String	Proper name, otherwise the HR/HIP designation; for Messier objects the Messier number
`raHours`	Number	Right ascension in hours (J2000)
`decDeg`	Number	Declination in degrees (J2000)
`vMag`	Number · null	Apparent visual magnitude
`bV`	Number · null	Colour index B−V
`hip`	Number · null	Hipparcos number
`hr`	Number · null	Bright Star Catalogue number
`type`	String	Deep-sky objects only, e.g. `Globular Cluster`

Example entry:

{
  "id": "3d0242ab-45c1-a393-4bda-b0c1920e03a0",
  "name": "Vega",
  "raHours": 18.61564,
  "decDeg": 38.783692,
  "vMag": 0.03,
  "bV": -0.001,
  "hip": 91262,
  "hr": 7001
}

What was changed against the originals

Filtered — from the HYG database only entries down to a limiting magnitude, with the sun excluded. From OpenNGC only the 110 Messier objects.
Converted — from the CSV files of both sources into a single JSON array with the fields named above. Columns not needed were dropped.
Given identifiers — every entry carries an id. It is deterministic: SHA-256 over the canonical string Name|RA:h:m:s|Dec:±d:m:s, the first 32 hex characters of it in UUID form. Same input, same id — on a repeat run too.
Merged — stars and deep-sky objects live in one file. The deep-sky objects are the ones with the type field set.
Renamed for the Messier objects — the display name is composed as M<number> <common name> (<NGC/IC number>). Where OpenNGC lists several common names the more usual one is chosen; for M101 (“Pinwheel Galaxy”) and M40 (“Winnecke 4”) the name was supplied, because OpenNGC carries none.
Mapped differently for M102 — OpenNGC lists M102 as a duplicate of M101. This catalogue follows the mapping to NGC 5866 that is usual today and therefore holds 110 distinct objects.
Compressed — gzip, so the file can ship with the app.

The script that builds the deep-sky part is in the project under tools/build_messier.py and loads OpenNGC directly from GitHub.

Sources and licence

Part	Source	Author	Licence
8,920 stars	HYG Database v4.1	Astronexus (David Nash)	CC BY-SA 4.0
110 Messier objects	OpenNGC	Mattia Verga	CC BY-SA 4.0

Both sources are licensed under the Creative Commons Attribution-ShareAlike 4.0 International License, and so is this adapted catalogue.