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Phase Spectra Seen from Space
Published online by Cambridge University Press: 08 February 2017
Extract
A 15 hour time series of simultaneous spectroscopic measurements of the continuum intensity, Doppler shift, and line depth in the Ni I 6768Å line at disk center of the quiet sun has been obtained during a guest investigator campaign with the Michelson Doppler Imager (MDI, see Scherrer et al. 1995). In addition, the line intensity has been calculated from the continuum intensity and the line depth data. The spatial shifts due to solar rotation have been approximately removed during the observation run by shifting the CCD read-out area by 1 pixel every 4 minutes. Small residual shifts have been removed during the data analysis. Before applying the Fourier analysis, a (temporal) low pass filtered mean velocity (line of sight component of solar rotation) and mean intensity (center-limb variation) has been removed from each frame. Finally, the continuum intensity (C), line intensity (I), and velocity (V) time series have been subjected to a 3D Fourier transform, yielding κ - ω power, cross power, phase difference, and coherence spectra. The data can now be compared to recent ground-based observations (Deubner, 1990; Deubner et al., 1992; Straus & Bonaccini, 1997).
- Type
- VII. The Solar Atmosphere
- Information
- Symposium - International Astronomical Union , Volume 185: New Eyes to See Inside the Sun and Stars , 1998 , pp. 455 - 456
- Copyright
- Copyright © Kluwer 1998