qs091.labonte01 Posted: 17-Jul-95 Updated: 26-Apr-96 Events specified: AR 7270
Barry LaBonte and Melinda Kellogg, University of Hawaii
Science question: High frequency oscillations probe the upper
layers of the solar convection zone. Their properties
are strongly affected by magnetic fields. We want to study
3 questions: What are the highest frequency waves
that are observable? What is the spatial distribution
of the enhancement of high frequency oscillations around
sunspot regions? Do high frequency waves show absorption
in sunspots?
Method: During flare mode observations, Yohkoh SXT took optical
PFI images at 10 second cadence. During some flares,
observations continued for entire daylight intervals.
The absence of disturbance by the Earth's atmosphere
make these data unique for observation of solar oscillations
at high temporal and spatial frequency.
Required data: A search of the Observing Log identified a series
of flare mode optical images in AR 7270 on September 5, 6,
and 7, 1992 as the best candidates for this study.
Update 26-Apr-96
Work on this project is in progress.
1). A new algorithm for constructing flat fields for the optical images using a Fourier technique has been developed and works well.
2). Coregistration of the images by corelation shows that for short timescales, the spacecraft pointing solution from the standard procedures is accurate to +/- 0.05 full-res pixel; solar rotation is easily seen over distances of a fraction of a pixel (~10 minutes).