Data obtained from our request page contains data at 5 second resolution. Vector magnetic field samples were obtained eight times a second, and the data originally recorded as 0.5 second averages. This data set is averaged over the 5 second interval centered on the time of the given measurement. The data, originally recorded in local geomagnetic coordinates, have been rotated into geographic coordinates. Similarly, plots obtained from the request page are based on this 5 second resolution data.

The 5 second data files are in binary format. Each 5 sec file contains data for one day for a single station. The naming convention is: 3 letter station abbreviation followed by yearday with the extension '.bin' (meaning binary data) such as 'gjo95154.bin'.

The record format of these 5 second binary data files is:

            record size(fixed) = 15 bytes
    number of records per file = 17280
                     file size = 259200 bytes
  flag for bad or missing data = 32767000

Byte Number Content Data Type
1 hour byte
2 minute byte
3 second byte
4-7 Bx(nT x 1000) 4 byte longint
8-11 By(nT x 1000) 4 byte longint
12-15 Bz(nT x 1000) 4 byte longint

Any use of these data must include a proper acknowledgment of their source. Please see our data use policy.