{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://github.com/api-evangelist/nasa/blob/main/json-schema/epic-image.json",
  "title": "EPIC Image",
  "description": "An Earth image from NASA's EPIC (Earth Polychromatic Imaging Camera) on DSCOVR.",
  "type": "object",
  "properties": {
    "identifier": {
      "type": "string",
      "description": "Unique identifier for the image."
    },
    "caption": {
      "type": "string",
      "description": "Caption describing the image."
    },
    "image": {
      "type": "string",
      "description": "Image filename without extension."
    },
    "version": {
      "type": "string",
      "description": "Version identifier."
    },
    "date": {
      "type": "string",
      "format": "date-time",
      "description": "Date and time the image was taken."
    },
    "centroid_coordinates": {
      "type": "object",
      "properties": {
        "lat": { "type": "number" },
        "lon": { "type": "number" }
      },
      "description": "Geographic coordinates of the image center."
    },
    "dscovr_j2000_position": {
      "$ref": "#/$defs/position"
    },
    "lunar_j2000_position": {
      "$ref": "#/$defs/position"
    },
    "sun_j2000_position": {
      "$ref": "#/$defs/position"
    },
    "attitude_quaternions": {
      "type": "object",
      "properties": {
        "q0": { "type": "number" },
        "q1": { "type": "number" },
        "q2": { "type": "number" },
        "q3": { "type": "number" }
      }
    }
  },
  "required": ["identifier", "image", "date"],
  "$defs": {
    "position": {
      "type": "object",
      "properties": {
        "x": { "type": "number" },
        "y": { "type": "number" },
        "z": { "type": "number" }
      }
    }
  }
}