{
  "credits_version": 1,
  "applies_to": "Every object at https://velvethours.space/forecast/v1/ (schema_version 1) and its index.",
  "sources": [
    {
      "input": "cloud",
      "source": "Environment and Climate Change Canada, HRDPS Continental through MSC GeoMet",
      "licence": {
        "name": "Environment and Climate Change Canada Data Services End-use Licence, version 2.1.1",
        "url": "https://eccc-msc.github.io/open-data/licence/readme_en/"
      },
      "attribution": [
        "Data Source: Environment and Climate Change Canada"
      ],
      "changes": "Total cloud at the site's grid point, converted from percent to a fraction 0 to 1."
    },
    {
      "input": "activity",
      "source": "GFZ German Research Centre for Geosciences, the Hp30 index",
      "licence": {
        "name": "CC BY 4.0",
        "url": "https://creativecommons.org/licenses/by/4.0/"
      },
      "attribution": [
        "GFZ German Research Centre for Geosciences"
      ],
      "citation": "Matzka, J., Bronkalla, O., da Silva, M. V., Kervalishvili, G., Rauberg, J., Korte, M., & Yamazaki, Y. (2024). Geomagnetic Hpo index (V3.0) [Dataset]. GFZ Data Services. https://doi.org/10.5880/hpo.0003",
      "changes": "In an outlook (activity.kind climatological) the value is the month's median of GFZ's Hp30 over dark intervals at the site, computed by Velvet Hours. In a nowcast (activity.kind measured) it is GFZ's value as published."
    },
    {
      "input": "brightness",
      "source": "NASA Black Marble, VNP46A4, 2025",
      "licence": {
        "name": "NASA Earth science data, no restrictions on use (CC0)",
        "url": "https://www.earthdata.nasa.gov/engage/open-data-services-software-policies/data-use-guidance"
      },
      "attribution": [
        "NASA"
      ],
      "citation": "NASA VIIRS Land Science Investigator-led Processing System. (2025). VIIRS/NPP Lunar BRDF-Adjusted Nighttime Lights Yearly L3 Global 15 arc second Linear Lat Lon Grid [Dataset]. NASA Level 1 and Atmosphere Archive and Distribution System Distributed Active Archive Center. https://doi.org/10.5067/VIIRS/VNP46A4.002",
      "changes": "Zenith sky brightness estimated by Velvet Hours from the satellite radiance; uncalibrated."
    },
    {
      "input": "horizon",
      "source": "Terrarium terrain tiles (AWS Open Data): ArcticDEM north of 60 N, and the Canadian Digital Elevation Model",
      "licence": {
        "name": "Per source: ArcticDEM released without limitation; CDEM under the Open Government Licence - Canada",
        "url": "https://github.com/tilezen/joerd/blob/master/docs/attribution.md"
      },
      "attribution": [
        "DEM(s) were created from DigitalGlobe, Inc., imagery and funded under National Science Foundation awards 1043681, 1559691, and 1542736.",
        "Contains information licensed under the Open Government Licence – Canada."
      ],
      "changes": "A horizon profile computed by Velvet Hours from the elevations; the object carries its id."
    }
  ],
  "project_terms": {
    "settled": false,
    "text": "Not yet set. Velvet Hours has not settled its own terms for reusing these objects. Until it does, ask first: mikayla@twst.studio. Each source's terms above apply whatever they become."
  }
}