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Web Service for Geomagnetism Data

February 9, 2022


BOU observatory data for current UTC day in IAGA2002 format

BOU observatory data for current UTC day in JSON format

BOU electric field data for current UTC day in IAGA2002 format,E-N&id=BOU&sampling_period=1&type=variation

See more examples below.


Request Limits

To ensure availability for users, the web service restricts the amount of data that can be retrieved in one request. The amount of data requested is computed as follows, where an interval is the number of seconds between start time and end time:

samples = count(elements) * interval / sampling_period

Limits by the output format


  • 172800 samples = 4 elements * 12 hours * 3600 samples/hour.


  • 345600 samples = 4 elements * 24 hours * 3600 samples/hour.
  • NOTE: while the json format supports fewer total samples per request, users may request fewer elements to retrieve longer intervals.



  • Observatory code. Required.


  • Time of first requested data.
  • Default: start of current UTC day
  • Format: ISO8601 (YYYY-MM-DDTHH:MM:SSZ)
  • Example: 2018-08-06T22:10:14Z


  • Time of last requested data.
  • Default: starttime + 24 hours
  • Format: ISO8601 (YYYY-MM-DDTHH:MM:SSZ)
  • Example: 2018-08-06T22:10:14Z


  • Comma separated list of requested elements.
  • Default: X,Y,Z,F
  • Valid values: D, DIST, DST, E, E-E, E-N, F, G, H, SQ, SV, UK1, UK2, UK3, UK4, X, Y, Z


  • Interval in seconds between values.
  • Default: 60
  • Valid values: 1, 60, 3600


  • Type of data.
  • Default: variation Valid values: variation, adjusted, quasi-definitive,definitive
  • NOTE: the USGS web service also supports specific EDGE location codes. For example: R0 is "internet variation",R1 is "satellite variation".


  • Output format.
  • Default: iaga2002
  • Valid values: iaga2002, json.

More Examples

Data from observatory BOU (defaults to current day if not specified):

One-second data from observatory BOU (defaults to current day if not specified):

Adjusted (one-min) data from observatory BOU:

Quasi-definitive data from observatory BOU for January 2016:

Definitive data from observatory BOU for March 1st, 2014:

Data from observatory BOU in HDZ (rather than XZY):,D,Z,F

Data from observatory BOU in HDZ for March 2016 (variation, one-min):,D,Z,F

Data for SQ, SV, or Dist for February 2016:,SV,DIST

Delta-F data from observatory BOU:

Data for Dst: