REMOVAL OF VELOCITY BIAS IN THE INTERPRETATION OF MEASUREMENTS OF THE AZIMUTHAL COMPONENT OF THE INTERPLANETARY MAGNETIC FIELD.

Parker's model for the interplanetary magnetic field predicts an r** minus **1 dependence for the azimuthal component. Departures from this relation were indicated in an analysis of a subset of the Helios 1 data. As in a previous analysis of Pioneer 10 data, these departures can be traced to velocity bias. This paper examines the decrease in solar wind speed which occurred as Helios 1 approached the sun and thus simulated a steeper gradient of the azimuthal magnetic field component. A simple linear fit between flow speed and distance from the sun makes it possible to remove from the data most of the velocity bias present. This procedure substantially improves the agreement between Parker's model and the Helios data.