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Session 37 - First Results from the Solar and Heliospheric Observatory (SOHO).
Display session, Tuesday, June 11
Tripp Commons,
The Structure Program for the Michelson Doppler Imager instrument on SOHO is designed to provide valuable helioseismic observations through a continuously operating 5 kbps telemetry channel. Only about 3% of the total MDI raw data can be transmitted without interruption to the ground. Therefore, extensive data processing must be performed by the MDI instrument in order produce data products that will fit into the restricted telemetry and to meet the scientific observing requirements.
The Structure Program consists of five observing programs: the Medium-l Velocity, Low-l (LOI) Velocity and Intensity, Limb Figure, Flux Budget, and Magnetic Proxy. These programs generate spatial and temporal averages of three of the MDI full disk observables: the velocity, computed continuum intensity, and the computed line depth. The performance of these filters will be described.
The goal of the Medium-l Program is to provide reliable measurements of solar p-modes in the range of the angular degree, l, from 0 to 300, by generating a 23,000 bin spatial average of the full disk velocity. The Low-l Program rebins the velocity and continuum intensity images into 180 bins, with the intent of observing long period global oscillations.
The other three Structure Observations are averaged over 24 minutes with a 12 minute sample time. The Limb Figure extracts a 14 arcsecond annulus at the Sun's limb in order to study long wavelength oscillations in the observed limb. The Flux Budget and Magnetic Proxy are 128 by 128 pixel rebins of the continuum intensity and line depth observables respectively, to study the solar luminosity and large scale features.
Extensive tests of the individual components of the Structure Program have been performed during the commissioning phase of the SOHO operation. Uninterrupted operation started in April 1996. This research is supported by NASA contract NAG5-3077 at Stanford University.
