Pioneer 10 magnetic field measurements, believed to include waves associated with the pick-up of interstellar hydrogen atoms, have been further analyzed. Power spectra and waveform data reveal that the signals previously interpreted as waves are an artifact. They resulted from a very low telemetry/sampling rate, associated with the large distance of Pioneer 10 from Earth, which caused aliasing of a sinusoidal signal at the spacecraft spin frequency to a low frequency just above the proton gyrofrequency. Thus the Pioneer 10 plasma analyzer evidence for interstellar pickup ions must be considered separately from the magnetometer data: The validity of the plasma measurements is not affected by this data artifact. ¿ 1998 American Geophysical Union