These experimenter-supplied, magnetometer data are on binary magnetic tape created on a CDC 6600 computer. The tape contains both 3-second and 5-minute averages of magnetic field components (given as Hp, He, and Hn) on separate files. Each logical record of the 3-second data contains the year, month, day of month, hour, and 3 minutes of 3-second data (time in minutes of the hour, Hp, He and Hn). The 5-minute average record also contains year, month, day of month, and hour plus one hour of 5-minute averages. Minute of the hour is not included in the 5-minute averages. The first set of values is centered around 5 minutes of the first hour and averages for each 5-minute period follow sequentially. All data values, excluding the time information, were multiplied by 100 so that they could be written as binary integers to facilitate reading.