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Instrument: VIS : Visible Imaging System (Polar)
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The Visible Imaging System (VIS) is a set of three low-light-level cameras
flown on the POLAR spacecraft of the International Solar-Terrestrial Physics
(ISTP) program. Two of these cameras share primary and some secondary optics
and are designed to provide images of the nighttime auroral oval at altitudes
~1 to 8 RE (Earth radius) as viewed from the eccentric, polar orbit of the
spacecraft. A third camera is used to monitor the directions of the
fields-of-view of the auroral cameras with respect to the sunlit Earth. The
auroral images are to be gained with filters with narrow passbands at visible
wavelengths. The emissions of interest include those from N2+ at 391.4 nm, Ol
at 557.7 and 630.0 nm, Hl at 656.3 nm and OII at 732.0 nm. The primary
scientific objectives of this imaging instrumentation, together with the in
situ measurements from instruments on board the ensemble of ISTP spacecraft,
are (1) quantitative assessment of the dissipation of magnetospheric energy
into the auroral ionosphere, (2) an instantaneous reference system for the
above in situ observations, (3) development of a substantial model of the
energy flow within the magnetosphere, (4) investigation of the topology of the
magnetosphere, and (5) delineation of the responses of the magnetosphere to
substorms and variable solar wind conditions.
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Instrument Logistics
Instrument Start Date: 1996-02-24
Instrument Owner: Lockheed Martin Astrospace
University of Iowa