Ultraviolet spectroscopy of the extended solar corona during the Spartan 201 mission

Abstract

The instruments on the Spartan 201 spacecraft are an Ultraviolet Coronal Spectrometer and a White Light Coronagraph. Spartan 201 was deployed by the Space Shuttle on 11 April 1993 and observed the extended solar corona for about 40 hours. The Ultraviolet Coronal Spectrometer measured the intensity and spectral line profile of HI Lyα and the intensities of OVI 103.2 and 103.7 nm. Observations were made at heliocentric heights between 1.39 and 3.5 R_⊙. Four coronal targets were observed, a helmet streamer at heliographic position angle 135°, the north and south polar coronal holes, and an active region above the west limb. Measurements of the HI Lyα geocorona and the solar irradiance were also made. The instrument performed as expected. Straylight suppression, spectral focus, radiometric sensitivity and background levels all appear to be satisfactory. The uv observations are aimed at determining proton temperatures and outflow velocities of hydrogen, protons and oxygen ions. Preliminary results from the north polar coronal hole observations are discussed.