THE INDUCED MAGNETOSPHERE OF COMET HALLEY - INTERPLANETARY MAGNETIC-FIELD DURING GIOTTO ENCOUNTER

Direction of the interplanetary magnetic field (IMF) which governs the orientation of the Halley's magnetosphere was restored by using Giotto magnetic field data. The Giotto trajectory was a twisted curve in the coordinate system rotating with IMF vector and covered rather uniformly the transverse cross section of the comet. Magnetic field vectors show a regular structure arising from the field line draping about the cometary ionosphere. Violations of the field line draping occur only at the moments of rapid changes of IMF orientation.