Calibration and Analysis of Ha Data to be Taken by SOTNFI

1
Calibration and Analysis of Ha Data to be Taken
by SOT/NFI

• Jongchul Chae
• Department of Physics and Astronomy
• Seoul National University, Korea

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

3
Ha absorbing/emitting features
chromosphere
photosphere
4
Contrast
5
Calibration

• Basic Processing
• Subtraction of darkbias
• Flat fielding
• Data Calibration
• Contrast calibration
• Intensity calibration
• Wavelength calibration
• Data restructuring
• Image alignment
• Constructing data cube
• Subsonic filtering

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

7
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)

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
  pixel0.38).

9
(No Transcript)
10

• Flat-Fielding of Solar Ha Observations Using
  Relatively Shifted Images (Chae 2004)

11
(No Transcript)
12
(No Transcript)
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

14
Cloud model fitting

• Model
• Inputs
• Outputs

15
(No Transcript)
16
Contrast profiles from a cube
17
Maps of physical parameters
18
Power of Ha imaging by SOT
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.