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Session 2 - Everything Else.
Display session, Friday, June 27
Ballroom C, Chair: Richard Canfield

[2.18] Phase-Diversity Restoration of two Simultaneous 70-minute Photospheric Sequences.

M. G. Löfdahl, T. E. Berger, R. A. Shine, A. M. Title (Lockheed Martin Advanced Technology Center)

Seeing effects have been corrected in two cospatial and cotemporal 70-minute sequences of images collected in the G-band 4305 Å\ and wideband 4686 ÅThe data were obtained with the 50 cm Swedish Vacuum Solar Telescope on the island of La Palma, Spain. The 29\arcsec\times 70\arcsec field-of-view (FOV) near disk center contains both an enhanced network region and an (apparently) non-magnetic ``quiet'' region of granulation. The mean time between restored frames is 23.5 s. Each of the 180 images is created with Phase-Diverse Speckle (PDS) imaging, using two different focus positions sampled at the best three snapshots of the atmospheric turbulence (seeing) during a 20-second selection window. Wavefronts are estimated for each focused--defocused image pair and a restored frame is produced from all six images. The average resolution in the restored sequence is about 0\farcs4 (corresponding to spatial frequencies up to half the diffraction limit of the telescope), which is good enough to allow detection of \sim0\farcs2 bright points. The data is used for statistical measurements of magnetic element speed, interaction frequency, and lifetime (see accompanying poster by T. E. Berger et al). We show destretched and space-time filtered movies of both the G-band and continuum images, as well as raw data to demonstrate the effect of the restoration process. This work was supported by NASA contracts NAS5-30386 at Stanford and NAS8-39747 and Independent Research Funds at Lockheed-Martin. MGL was supported by the Swedish Science Research Council.

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