{
  "retrieved": "2026-10-25",
  "objectCount": 6,
  "purpose": "Curated destination gallery; not an astrometric map.",
  "units": {
    "distanceLy": "light-years",
    "secondaryFact": "Unit is explicit on each object; solar mass is the mass of the Sun."
  },
  "notes": [
    "Distances are rounded estimates adopted from the cited outreach/catalog sources. Different methods and publications can report different values; these are not precision measurements or per-object uncertainties.",
    "No RA/Dec, spatial coordinates, angular sizes, or 3D volume reconstruction are supplied. Constellation names indicate apparent sky direction, not physical membership.",
    "Nebula/galaxy x/y morphology and filter-assigned colors use official Hubble and Webb images. Camera-facing observation projections fade to image-sampled clouds when orbiting. All depths, thicknesses, navigable star positions and travel remain illustrative; they are not measured 3D reconstructions or naked-eye colors.",
    "Black-hole rings illustrate nearby emitting gas and gravitational effects, not a luminous solid surface or the event horizon itself.",
    "Apparent magnitude refers to the integrated object; it does not imply uniform surface brightness or easy naked-eye visibility.",
    "Korean names and concise summaries are original paraphrases. Eight credited official observation images are included; full image sources, dates, licenses and processing: observations/deep-observations.json."
  ],
  "sources": [
    {
      "objectId": "SagA",
      "title": "NASA Animation Sizes Up the Universe’s Biggest Black Holes",
      "publisher": "NASA Goddard Space Flight Center",
      "url": "https://www.nasa.gov/universe/nasa-animation-sizes-up-the-universes-biggest-black-holes/",
      "supports": [
        "distanceLy=26000",
        "secondaryFact.value=4300000 solar masses",
        "Milky Way central black hole"
      ],
      "supplementaryUrls": [
        "https://www.nasa.gov/news-release/nasas-swift-catches-x-ray-action-at-milky-ways-center/"
      ],
      "notes": "Adopts NASA 2023 article, updated February 5, 2024. Some EHT releases round the distance to 27000 light-years and mass to four million solar masses; this catalog uses one internally consistent NASA estimate."
    },
    {
      "objectId": "M87BH",
      "title": "Astronomers Capture First Image of a Black Hole",
      "publisher": "Event Horizon Telescope Collaboration",
      "url": "https://eventhorizontelescope.org/press-release-april-10-2019-astronomers-capture-first-image-black-hole",
      "published": "2019-04-10",
      "supports": [
        "distanceLy=55000000",
        "secondaryFact.value=6500000000 solar masses",
        "2019 first image release",
        "M87 host galaxy"
      ],
      "supplementaryUrls": [
        "https://science.nasa.gov/mission/hubble/science/explore-the-night-sky/hubble-messier-catalog/messier-87/"
      ],
      "notes": "Mass is specifically the 2019 EHT estimate. Other techniques give different mass estimates; NASA’s 2023 black-hole animation cites 5.4 billion solar masses. The catalog deliberately labels this EHT estimate rather than claiming a unique exact or latest mass. Virgo constellation comes from NASA Hubble M87 catalog."
    },
    {
      "objectId": "M42",
      "title": "Messier 42 — The Orion Nebula",
      "publisher": "NASA Hubble",
      "url": "https://science.nasa.gov/mission/hubble/science/explore-the-night-sky/hubble-messier-catalog/messier-42/",
      "supports": [
        "distanceLy=1500",
        "apparent magnitude 4.0",
        "Orion constellation",
        "stellar nursery and Trapezium cluster"
      ],
      "notes": "Adopts rounded NASA Hubble catalog distance; literature measurements differ. No inferred 3D arrangement of gas or stars is supplied."
    },
    {
      "objectId": "Helix",
      "title": "Caldwell 63 — Helix Nebula",
      "publisher": "NASA Hubble",
      "url": "https://science.nasa.gov/mission/hubble/science/explore-the-night-sky/hubble-caldwell-catalog/caldwell-63/",
      "supports": [
        "distanceLy=650",
        "NGC 7293 / Caldwell 63",
        "Aquarius constellation",
        "planetary nebula",
        "bright ring nearly three light-years across"
      ],
      "notes": "The 3-light-year fact describes the bright ring; fainter outer structures extend farther. Planetary nebula is an evolutionary category and does not refer to a planet."
    },
    {
      "objectId": "M31",
      "title": "Messier 31 — The Andromeda Galaxy",
      "publisher": "NASA Hubble",
      "url": "https://science.nasa.gov/mission/hubble/science/explore-the-night-sky/hubble-messier-catalog/messier-31/",
      "supports": [
        "distanceLy=2500000",
        "apparent magnitude 3.1",
        "Andromeda constellation",
        "spiral galaxy",
        "nearest major galaxy to the Milky Way"
      ],
      "notes": "Uses NASA Hubble catalog magnitude and rounded distance. Nearby dwarf galaxies are closer than M31; summary specifically says major galaxy."
    },
    {
      "objectId": "M51",
      "title": "Messier 51 — The Whirlpool Galaxy",
      "publisher": "NASA Hubble",
      "url": "https://science.nasa.gov/mission/hubble/science/explore-the-night-sky/hubble-messier-catalog/messier-51/",
      "supports": [
        "distanceLy=31000000",
        "apparent magnitude 8.4",
        "Canes Venatici constellation",
        "spiral galaxy",
        "NGC 5195 interaction"
      ],
      "notes": "Uses 31 million light-years from the cited Hubble catalog. Published distances vary; 3D gallery scale must not imply measurement precision."
    }
  ],
  "observationManifest": "observations/deep-observations.json"
}