PR Gazis,
A Barnes, JD Mihalov… - Journal of Geophysical …, 1994 - Wiley Online Library
At the end of 1992, the Pioneer 10, Pioneer 11, and Voyager 2 spacecraft were at
heliocentric distances of 56.0, 37.3, and 39.0 AU and heliographic latitudes of 3.3° N, 17.4° …