Abstract. The Voyager 1 outbound ultraviolet observations of the Io plasma torus are
used to determine the location of the ansae, to obtain a third viewing angle
of this structure in the Jovian magnetosphere. At an angle of -114∘
with respect to the Sun–Jupiter line, or a Jovian local time of 04:30 LT,
the Voyager 1 data deliver a distance of 5.74±0.10 RJ for
the approaching and 5.83±0.15 RJ for the receding ansa.
Various periodicities in the radial distance, brightness and width of the
ansae are seen with respect to system III longitude and Io phase angle. The
torus ribbon feature does not appear in all ansa scans. Keywords. Magnetospheric physics (magnetosphere interactions with satellites and rings)
RMSE is not enough: Guidelines to robust data-model comparisons for magnetospheric physics