Copyright WDC C1 for STP at RAL.
This consists of two datasets; one gives 5-minute averages of the Interplanetary Magnetic Field from the ISEE3 spacecraft, and the other gives the position of the spacecraft. Data is available from 1979-06-29 to 1983-12-31. Note that the data coverage is not continuous. In particular there is no data between 1982-12-22 and 1983-10-31 inclusive.