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NOAO Newsletter - National Solar Observatory - March 2000 - Number 61


Diffraction-Limited Magnetogram Movies

Christoph Keller, Thomas Rimmele, and Rick Paxman

Rick Paxman, John Seldin, Dave Carrara, and Kurt Gleichman of ERIM International in Ann Arbor, Michigan, and Thomas Rimmele and Christoph Keller of NSO recently joined forces to obtain the highest resolution magnetogram movies ever obtained. The ERIM team was responsible for restoring the images with phase-diverse speckle imaging; Rimmele operated the adaptive optics system at the Dunn Solar Telescope to provide the best possible image quality, and Keller ran the Zurich Imaging Polarimeter I (ZIMPOL) and performed the speckle deconvolution of the narrow-band images and magnetograms. The adaptive optics corrected the low-order aberrations with an update rate of about 1.5 kHz and fed a narrow-band channel with the Universal Birefrin-gent Filter in the wing of the Ca I 610.3 nm line and two white-light channels that were used to obtain an in-focus and an out-of-focus image for the phase-diversity processing, which removes the remaining aberrations. All three channels were equipped with a ZIMPOL I camera running simultaneously at 5 frames/s. The one-hour dura-tion was limited by the available hard-disk space.

This combined attack for obtaining the best magnetogram movies of the solar surface was very successful and led to spectacular time sequences with a consistent spatial resolution of better than 0.2". While the team is still optimizing their data reduction process, they have made some movies available via the web at http://www.noao.edu/noao/staff/keller/aopds . An example of a single frame from one of the movies is shown below.


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