spase://NASA/NumericalData/ISEE3/MAG/CDF/PT1M

This Data Set contains averaged 1 min magnetic field data converted from simple ASCII records. It was created at the NSSDC from a more complex, multi-resolution data set with the current NSSDC ID of SPHE-00673 and old NSSDC ID of 78-079A-02D, provided by the Principal Investigator Team and now available from ftps://spdf.gsfc.nasa.gov/pub/data/isee/isee3/magnetic_fields/1min_ascii_extracted/. The Coordinate System for the magnetic field components is the JPL-defined I,S Coordinate System set at the origin at the spacecraft: I is the unit vector in the direction of the ISEE 3 spin axis, positive in the northward direction, and S is the unit vector from the spacecraft to the sun. The Z-Axis is parallel to I, the Y-Axis is parallel to the cross product I ⨯ S, and the X-Axis is parallel to Y ⨯ Z. The I,S coordinate system is approximately the same as the Solar Ecliptic, SE, System since the Spacecraft Z-Axis, the Spin Axis, is maintained within 0.5° of perpendicular to the Ecliptic Plane. The SE coordinate system is defined in the same way as GSE, but with the spacecraft point of observation substituted for the position of the earth. For years 1984 through 1990 the spacecraft position in HGI coordinates was added to the data product. The HGI coordinate system is sun-centered and inertially fixed with respect to an X-Axis directed along the intersection line of the Ecliptic and Solar Equatorial planes, which defines the 0° longitude direction. The Solar Equatorial plane is inclined at 7.25° from the Ecliptic. This direction was towards an Ecliptic longitude equal to 74.367° on January 1, 1900 at 12:00 UT, but because of the precession of the earth's equator, this longitude increases by 1.4° per century. The Z-Axis is directed perpendicular to and northward of the solar equator and the Y-Axis completes the right-handed Set. The HGI longitude increase from 0° in the X-Direction towards the positive Y-Direction. The HGI latitude increases to +90° at the north pole and decreases to -90° at the south pole. Note that the values listed are 1 min averages, so that B ^2 may not equal B^2 .