data

Data Formats

For GeoJSON, all coordinates need to be given in degrees, longitude as [-180...180] deg, latitude as [-90...90] deg

Stars
stars.6.json, stars.8.json; the number indicates limit magnitude

{
  "type": "FeatureCollection",
  "features": [{
    "type": "Feature",
    "id": "",        // Hipparcos number
    "properties": {
      "name": "",    // Proper name
      "desig": "",   // Bayer, Flamsteed, variable, Gliese, HD, HIP
      "mag": "",     // Apparent magnitude
      "bv": ""       // b-v color index
    },
    "geometry": {  
      "type": "Point",
      "coordinates": [lon, lat]
    }
  }, { } ]
}

DSOs
dsos.6.json, dsos.14.json: the number indicates limit magnitude
dsos.bright.json: handselected
lf.json: Local group

{
  "type": "FeatureCollection",
  "features": [{
    "type": "Feature",
    "id": "",       // Short designator
    "properties": {
      "name": "",   // Proper name or most commonly used designator
      "desig": "",  // Designator
      "type": "",   // Object type: gg, g, s, s0, ds, i, e, oc, gc, dn, bn, sfr, rn, pn, snr
      "mag": "",    // Apparent magnitude, 999 if n.a.
      "dim": ""     // Angular dimensions in arcminutes
    },
    "geometry": {  
      "type": "Point",
      "coordinates": [lon, lat]
    }
  }, { } ]
}

Object type gg: galaxy cluster, g: galaxy, s: spiral galaxy, s0: lenticular gal., ds: dwarf gal., i: irregular gal., e: elliptical gal.,
oc: open cluster, gc: globular cluster, dn: dark nebula, bn: bright nebula, sfr: star forming region, rn: reflection nebula, pn: planetary nebula, snr: supernova remnant

additional lg.json properties:
sub: Sub group membership: [MW|M31|N3109|LG] (Milky way, Andromeda, NGC 3109, gen. LG)
pop: MW popultions [OH|YH|BD] (Old halo, young halo, bulge & disk), M31 populations [M31|GP] (gen. M31, great plane)
str: Tidal streams [Mag|Sgr|CMa|FLS] (Magellanic Stream, Sagittarius Stream, Canis Major/Monoceros Stream, Fornax-Leo-Sculptor Great Circle)

Constellations
constellations.json

{
  "type": "FeatureCollection",
  "features": [{
    "type": "Feature",
    "id": "",           // 3-letter designator
    "properties": {
      "name": "",       // full name
      "genitive": "",   // for naming stars, not yet used
      "desig": "",      // 3-letter designator again
      "display": []     // [ra,dec,scale], for single constellation display (tbi)
    },
    "geometry": {  
      "type": "Point",
      "coordinates": [lon, lat]  // Position of const. name
    }      
  }, { } ]
}

Constellation lines
constellations.lines.json

{
  "type": "FeatureCollection",
  "features": [{
    "type": "Feature",
    "id": "",           // 3-letter designator of constellation
    "geometry": {  
      "type": "MultiLineString",
      "coordinates": [[[lon, lat],[lon, lat],..],[[]lon, lat,[lon, lat],..],..]
    }
  }, { } ]
}

Constellation boundaries
constellations.bounds.json

{
  "type": "FeatureCollection",
  "features": [{
    "type": "Feature",
    "id": "",           // 3-letter designator of constellation
    "geometry": {  
      "type": "Polygon",
      "coordinates": [[[lon, lat],[lon, lat],..]]
    },
  }, { } ]
}

Milky way
mw.json

{
  "type": "FeatureCollection",
  "features": [{
    "type": "Feature",
    "id": "",       // ol 1-5
    "properties": {},
    "geometry": {
      "type": "MultiPolygon",
      "coordinates":[[[[lon, lat],[lon, lat],..],[[lon, lat],[lon, lat],..],..]]
    }
  }, { } ]
}

Special Planes

{
  "type": "FeatureCollection",
  "features": [{
    "type": "Feature",
    "id": "",       
    "geometry": {  
      "type": "LineString",
      "coordinates": [[lon, lat],[lon, lat]]
    }
  }, { } ]
}

Asterisms

{
  "type": "FeatureCollection",
  "features": [{
    "type": "Feature",
    "id": "",       // Name without spaces
    "properties": {
      "n": "",      // Proper name
      "es": "",     // Proper name in spanish
      "loc": [lon,lat], // Center location of name string
      "p": n        // Priority 1..6 (~Average brighness)
                    // p=6: Guiding line
    },
    "geometry": {  
      "type": "MultiLineString",
      "coordinates": [[[lon, lat],[lon, lat],..],[[]lon, lat,[lon, lat],..],..]
    }
  }, { } ]
}

Planets Not geojson, because positions need to be calculated by date from keplerian elements
All element values in degrees, except a (AU|km) and e (dimensionless)

"id":{                // (usually) 3-letter id
  "name": "",         // full name
  "trajectory": bool, // show trajectory (tbi)
  "H": n,             // absolute magnitude
  "elements":[{
    "a": "da": Semimajor axis / change per century (all 'dx' fields)
    "e": "de": Eccentricity
    "i": "di": Inclination
    "L": "dL": or "M": "dM": mean longitude (M*Q) or mean anomaly
    "W": "dW": or "w": "dw": longitude of periapsis (w*N) or argument of periapsis
    "N": "dn": longitude of the ascending node
    "ep":"2000-01-01" epoch, default date
  }]}