{
  "models": [
    {
      "order": 1,
      "model": "TAN",
      "training_stars": 959,
      "validation_stars": 232,
      "validation_median_original_pixels": 0.7374425111303266,
      "validation_p90_original_pixels": 1.580852611284427,
      "training_median_original_pixels": 0.7405022378618118
    },
    {
      "order": 2,
      "model": "TAN-SIP 2",
      "training_stars": 959,
      "validation_stars": 232,
      "validation_median_original_pixels": 0.6939134070904998,
      "validation_p90_original_pixels": 1.4207969146877137,
      "training_median_original_pixels": 0.6452680169461545
    },
    {
      "order": 3,
      "model": "TAN-SIP 3",
      "training_stars": 959,
      "validation_stars": 232,
      "validation_median_original_pixels": 0.5239026303821681,
      "validation_p90_original_pixels": 1.4098758850957833,
      "training_median_original_pixels": 0.5533146016860628
    },
    {
      "order": 4,
      "model": "TAN-SIP 4",
      "training_stars": 959,
      "validation_stars": 232,
      "validation_median_original_pixels": 0.5146027140936491,
      "validation_p90_original_pixels": 1.3987225858690182,
      "training_median_original_pixels": 0.55772878019295
    },
    {
      "order": 5,
      "model": "TAN-SIP 5",
      "training_stars": 959,
      "validation_stars": 232,
      "validation_median_original_pixels": 0.7202024424301925,
      "validation_p90_original_pixels": 1.6676064630984695,
      "training_median_original_pixels": 0.7220095155103534
    }
  ],
  "selected": {
    "order": 3,
    "model": "TAN-SIP 3",
    "training_stars": 959,
    "validation_stars": 232,
    "validation_median_original_pixels": 0.5239026303821681,
    "validation_p90_original_pixels": 1.4098758850957833,
    "training_median_original_pixels": 0.5533146016860628
  },
  "selection_rule": "Simplest within 5% of best validation median and 10% of its p90",
  "warp_grid_median_original_pixels": 0.5355719212022323,
  "warp_grid_max_original_pixels": 4.71470103921191,
  "star_supported_warp_max_original_pixels": 1.8923046313941791,
  "local_models": [
    {
      "smoothing": 1e-05,
      "median_original_pixels": 0.41153131519870884,
      "p90_original_pixels": 1.270073505050319
    },
    {
      "smoothing": 0.0001,
      "median_original_pixels": 0.35447137114045285,
      "p90_original_pixels": 1.1704812538280562
    },
    {
      "smoothing": 0.001,
      "median_original_pixels": 0.3401415213417979,
      "p90_original_pixels": 1.1817632469508355
    },
    {
      "smoothing": 0.01,
      "median_original_pixels": 0.3218906809840366,
      "p90_original_pixels": 1.317962582018346
    },
    {
      "smoothing": 0.1,
      "median_original_pixels": 0.3101751548468653,
      "p90_original_pixels": 1.3990779142737737
    },
    {
      "smoothing": 1.0,
      "median_original_pixels": 0.3450351543237715,
      "p90_original_pixels": 1.3957843928376545
    }
  ],
  "selected_local_model": {
    "smoothing": 0.001,
    "median_original_pixels": 0.3401415213417979,
    "p90_original_pixels": 1.1817632469508355
  },
  "local_selection_rule": "Minimum median + 0.25 times p90 on held-out stars; model-selection estimates, not an external accuracy certification.",
  "region": "X 251–4700, Y 251–5800; scan borders excluded",
  "interpretation": "Combined image distortion; cannot assign a separate physical glass contribution from one scan.",
  "caveat": "Held-out set was selected within 3.5 binned pixels of initial WCS; no plate-epoch proper-motion correction."
}