1. Calibration and Analysis of Ha Data to be Taken by SOT/NFI
Calibration and Analysis of Ha Data to be Taken by SOT/NFI
Jongchul Chae
Department of Physics and Astronomy
Seoul National University, Korea
17th SOT meeting
17th SOT meeting

2. Science from Ha observations
Chromosphere = a zoo of dynamic plasma features including
prominences/filaments
fibrils, spicules, grains
surges, jets, upflow events ?
Key physical processes
chromospheric magnetic reconnection
MHD waves
Ha imaging spectroscopy
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3. Ha absorbing/emitting features
chromosphere
photosphere
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4. Contrast
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5. Calibration Basic Processing Data Calibration Data restructuring
Subtraction of dark+bias
Flat fielding
Data Calibration
Contrast calibration
Intensity calibration
Wavelength calibration
Data restructuring
Image alignment
Constructing data cube
Subsonic filtering
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6. Analysis Morphological change Brightness change
Transverse velocity from tracking
Cloud model analysis of contrast profile
Line-of-sight velocity
Optical thickness
Absorption width
Source function
Other spectral analyses
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7. An example: Imaging Ha spectroscopy from Ground
An example: Imaging Ha spectroscopy from Ground
Flat-fielding (Chae 2004, Solar Physics)
Contrast & Data restructuring
Cloud model fit to the contrast profile (Chae et al. 2006, Solar Physics)
17th SOT meeting
17th SOT meeting

8. Observations 10 inch refractor at Big Bear Solar Observatory
One cycle of Lyot Ha filter (0.25 A bandwidth) tuning to -0.6, -0.3, 0.0, +0.3, +0.6 A in 15 s
Dalstar 1M30P Camera (12-bit, 30 fps, 20% QE, 1 pixel=0.38”).
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9.
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10. Flat-Fielding of Solar Hα Observations Using Relatively Shifted Images (Chae 2004)
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11.
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12.
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13. Data restructuring:
Input: a sequence of two-dimensional images for each run
Output: a data cube, that is, a four-dimensional array of contrast for each run
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14. Cloud model fitting
Model
Inputs:
Outputs:
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15.
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16. Contrast profiles from a cube
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17. Maps of physical parameters
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18. Power of Ha imaging by SOT
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From the 1m Swedish Telescope (courtesy of O. Engvold)

19. Suggested SOT observing sequences
7 wavelengths at -0.9, -0.6, -0.3, 0., +0.3, +0.6, +0.9 A and a frame size of 2k by 2k.
One cycling may take the duration of 33 s and the disk space of 10.5 Mb.
One flat-fielding observation consists of 9 cycles with moving the telescope pointing.
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