{
  "HAPI": "3.3.1",
  "status": {
    "code": 1200,
    "message": "OK"
  },
  "startDate": "1932-01-01T01:30:00Z",
  "stopDate": "2026-09-01T01:30:00Z",
  "cadence": "PT3H",
  "timeStampLocation": "center",
  "modificationDate": "2026-09-23T10:35:04Z",
  "title": "Kp and ap Indices (Definitive, 3-hour)",
  "description": "Planetary geomagnetic 3-hourly indices Kp and ap (definitive): Kp, introduced by Bartels (1949) and endorsed by IAGA, is derived from K-values recorded at 13 geomagnetic observatories; ap is the equivalent planetary amplitude (unit: 2 nT) derived from Kp. Kp is encoded as a decimal where the plus/minus thirds map to fractional parts .3 and .7 (e.g. 3−=2.7, 3o=3.0, 3+=3.3). Produced by GFZ Potsdam, redistributed by WDC for Geomagnetism, Kyoto. Timestamps are bin centers of each 3-hour interval (01:30, 04:30, ... 22:30 UT; timeStampLocation=center).",
  "resourceID": "doi:10.5880/Kp.0001",
  "datasetCitation": "Matzka, J., Stolle, C., Yamazaki, Y., Bronkalla, O., & Morschhauser, A. (2021). The Geomagnetic Kp Index and Derived Indices of Geomagnetic Activity. Space Weather, 19, e2020SW002641. doi:10.1029/2020SW002641. Kp index data: Matzka, J., Bronkalla, O., Tornow, K., Elger, K., & Stolle, C. (2021), Geomagnetic Kp index, V. 1.0, GFZ Data Services, doi:10.5880/Kp.0001. Redistributed via WDC for Geomagnetism, Kyoto.",
  "licenseURL": "https://creativecommons.org/licenses/by/4.0/",
  "parameters": [
    {
      "name": "Time",
      "type": "isotime",
      "units": "UTC",
      "fill": null,
      "length": 24,
      "label": "Time"
    },
    {
      "name": "kpValue",
      "type": "double",
      "units": null,
      "fill": "99.9",
      "label": "Kp",
      "description": "Planetary K index (0-9 scale), 3-hourly. Plus/minus thirds encoded as decimals .3 and .7 (3−=2.7, 3o=3.0, 3+=3.3)."
    },
    {
      "name": "apValue",
      "type": "integer",
      "units": null,
      "fill": "999",
      "label": "ap",
      "description": "Equivalent planetary amplitude (unit: 2 nT), 3-hourly, derived from Kp."
    },
    {
      "name": "versionCode",
      "type": "integer",
      "units": null,
      "fill": null,
      "label": "Version Code",
      "description": "Processing status code Mm (major*10+minor). Currently a single definitive version (versionCode 20)."
    }
  ],
  "x_LastUpdate": "2026-09-23T15:05:53Z"
}