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Summary: NH Long Range Reconnaissance Imager (LORRI)
images (17). This same feature appears in the HST/
SBC image in Fig. 2B, obtained when East Girru
was shifted just behind the limb. The auroral feature
near East Girru in both LORRI and HST/SBC im-
ages is ~15° northward of Jupiter's field line tangent
point at the limb, which suggests that ionospheric
currents are diverted northward from this nominal
position toward a region of higher gas density near
the plume. Similar deviations of the anti-jovian FUV
emissions from nominal tangent points observed
with STIS are likely caused by the prevalence and
distribution of plumes there (21). Volcanic plume
aurorae were not identified in previous lower-quality
STIS FUV images, which caused an apparent dis-
crepancy with visible images of plume aurorae. The
East Girru plume FUV auroral feature in Fig. 2 re-
solves this discrepancy and reveals the influence of
plumes on Io's electrodynamic interaction. The
upstream-side emission feature is more apparent
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