{
  "title": "미리내 밤하늘 · 좌표와 표현의 기준",
  "coordinates": {
    "engine": "Astronomy Engine · Don Cross",
    "source": "https://github.com/cosinekitty/astronomy/blob/master/source/js/README.md#rotation_gal_eqj--rotationmatrix",
    "license": "MIT",
    "licenseUrl": "https://github.com/cosinekitty/astronomy/blob/master/LICENSE",
    "frame": "IAU Galactic -> J2000 equatorial -> true equator of date -> apparent horizon",
    "functions": [
      "Rotation_GAL_EQJ",
      "Rotation_EQJ_EQD",
      "Horizon"
    ],
    "mapping": "The observed panorama is projected in the IAU Galactic frame: l=0 at the image centre, increasing longitude to the left, north latitude at the top. The unchanged GAL -> EQJ -> equator-of-date -> refracted horizon path remains shared with the HYG stars.",
    "update": "Recomputed when the observation city or time changes. Camera dragging changes the view, not the celestial coordinates."
  },
  "stars": {
    "source": "https://github.com/astronexus/HYG-Database",
    "catalogue": "HYG v4.1, J2000 positions and apparent magnitudes",
    "license": "CC BY-SA 4.0",
    "rendering": "Catalogue apparent magnitude controls compressed display brightness and compact point size; a 1.4 display gain with a tighter core and subdued halo improves clarity while retaining magnitude ordering. Catalogue stellar color is desaturated for a low-light appearance. Illustrative scintillation combines two smooth rhythms with independent per-star speeds and phases, centred on the unchanged base brightness and bounded to +/-3.5% overhead and +/-10% near the horizon. Point size and colour remain steady; reduced-motion mode uses the unmodulated brightness. Low-altitude extinction is illustrative. No extra randomly placed stars are added."
  },
  "milkyWay": {
    "representation": "Observed visible-light photographic all-sky mosaic, displayed as the diffuse Milky Way background",
    "credit": "ESO/S. Brunier",
    "copyright": "© Serge Brunier et Frédéric Tapissier",
    "source": "https://www.eso.org/public/images/eso0932a/",
    "releaseSource": "https://www.eso.org/public/news/eso0932/",
    "download": "https://cdn.eso.org/images/publicationjpg/eso0932a.jpg",
    "license": "CC BY 4.0",
    "licenseUrl": "https://creativecommons.org/licenses/by/4.0/",
    "usagePolicy": "https://www.eso.org/public/copyright/",
    "observed": "2008-08 through 2009-02",
    "released": "2009-09-14",
    "retrieved": "2026-10-25",
    "instrument": "Nikon D3; ground-based visible-light exposures from Chile and La Palma",
    "asset": "assets/eso0932a-milky-way.jpg",
    "width": 4000,
    "height": 2000,
    "sha256": "5363732a1629eed9df2f707b31eaae6b117c0ee35d7cc8d6ddd636bc6512302d",
    "fileChanges": "None. ESO publication JPEG is stored byte-for-byte, including its embedded CC BY 4.0 and author metadata.",
    "projection": {
      "type": "galactic plate-carree",
      "imageCentre": [
        0,
        0
      ],
      "longitudeDirection": "left",
      "latitudeDirection": "up",
      "textureFlipY": true,
      "u": ".5 - l / 360",
      "v": ".5 + b / 180"
    },
    "displayProcessing": "GPU trilinear mipmap filtering with bias 1.25 softens compact photographic stars without offset copies or generated detail. Original RGB is retained without exposure amplification; a 0.32 blend contribution keeps the long-exposure panorama behind the foreground catalogue stars. The band fades from |b|=12 to 24 degrees, fades near the horizon, and is occluded by terrain. No generated dust or replacement nebulae are added.",
    "limits": "Historical stitched panorama, not a live image or calibrated astrometric/photometric survey. Local mosaic distortions remain; precisely selectable foreground stars retain HYG coordinates. The source may contain historical solar-system objects, whose compact image cores are attenuated along with stars; it is not used to calculate present planet positions. Apparent brightness does not model daylight, moonlight, weather or urban light pollution."
  },
  "ground": {
    "representation": "Fictional low ridgeline and ground",
    "limits": "Not a terrain map of Seoul, Jeju, Sydney or Reykjavik. Ground blocks stars, constellation lines, labels and the Milky Way; card-based exploration of hidden objects remains available."
  },
  "visibility": "The scene intentionally remains a dark-sky exploration view at all input times. Daylight, moonlight, weather and light pollution are not simulated. The observation time is never silently changed to night. Reduced-motion mode disables scintillation."
}