We thank Science for their permission to use an
Broadfoot, A. L., et al. 1989.
Ultraviolet Spectrometer observations of Neptune and Triton.
Science 246 (4936), 1459-1466.
(Excerpt from p. 1465.)
Copyright AAAS, December 15, 1989.
Ultraviolet Spectrometer observations of Neptune and Triton
In addition to the atmospheric occultations described here, the UVS
also observed an occultation of the B2.5 V star sigma Sagittarii by the
ring system. This occultation
(Table 1), which was simultaneously
observed by the photopolarimeter experiment (29), intersected the ring
plane between 3.1 and 1.7 R_N. The only event unambiguously
identified in the UVS data is associated with N1R. This event appears as
a low tau feature (mean tau = 0.02) having a total width of approximately
35 km with a somewhat more opaque central core ~15 km wide. The
equivalent width, defined as the width-integrated optical depth of the
ring, was found to be 0.66 +/- 0.12 km. The absorption feature caused
by the ring is centered at spacecraft event time 236/23:24:46.37, which
corresponds to a planetocentric radius of 62,843 km for the ring,
assuming a Neptune rotation pole of right ascension alpha = 298.9
degrees and declination delta = 42.8 degrees.
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