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Coronal Observation 4

Purpose: Measurement of kinetic temperatures for H I, O VI, Mg X, Fe XII and Si XII. Primary observable quantities: line profiles for these ions. This mode is expected to be used 10% of the time.

Description: Duration 1 to 6 hours. There will be several versions with different dwell times, each one optimized for a particular target (streamers, quiet corona, coronal holes). Scan telescope mirror from selectable radial position 1.5 to 5.0 R (TBC). There are 10 mirror positions, with step size ranging from 0.2 to 0.5 R (TBC). At each mirror position, first measure resonantly scattered Ly-alpha and Fe XII 1242 Å profiles. A series of exposures is obtained with slightly different grating positions (``dither motion"). There are 20 grating positions with steps of 0.01 Å (TBC). Then move Ly-alpha grating such that resonantly scattered line falls on blocked section of XDL detector, and continue measurement of the FeXII 1242 Å profiles (without dither motions). Dwell times increase with height in the corona.

The O VI 1032/1037 Å profiles are also measured, using dither motion. There are 20 grating positions with steps of 0.01 Å (TBC). Dwell times increase with height in the corona. Polarized visible radiance will be measured at one pixel along the slit for each mirror position.



Peter Smith
Fri Jan 17 12:11:15 EST 1997