Read FISS data¶

Data format¶

There are two kinds of level 1 data: one is the processed data that has the filename of either '*1.fts', and the other is the compressed data that compresses the processed data using principle component analysis (PCA). The compressed data has two files one is the eigenvalue with the filename of '*_c.fts', and another is the eigenvector with the name of '*_p.fts'. To reconstruct the data, these two types of files should be in the same directory. Among these two, only the '*_c.fts' file will be used to read the data, and '*_p.fts' is used passively.

The table below summarizes these file types:

File types	Description
\*1.fts	Processed data.
\*_c.fts	Eigenvalue of the compressed data (main file).
\*_p.fts	Eigenvector of the compressed data (sub file).

Read Data¶

Now, we are ready to read the FISS data. Here, we show how to handle the compressed data (*_c.fts), but you can also use the same method for the processed data (*1.fts).

To read the FISS data we use the fisspy.read.FISS module:

In [ ]:

import fisspy
fname = './FISS_20140603_170841_A1_c.fts'
fiss = fisspy.read.FISS(fname)

You can read the data with the shape of (y,x,λ) and the header with the .data and .header attributes.

In [ ]:

fiss.data

Out[ ]:

array([[[7116.11181641, 7123.06005859, 7115.08935547, ...,
         7320.97900391, 7324.15869141, 7324.78466797],
        [7012.34667969, 7019.34082031, 7011.31054688, ...,
         7343.17773438, 7347.43310547, 7347.41552734],
        [7006.23193359, 7010.51171875, 7003.09912109, ...,
         7303.20996094, 7307.27441406, 7307.81689453],
        ...,
        [7113.49462891, 7114.36230469, 7106.13232422, ...,
         7631.99072266, 7633.38232422, 7634.62695312],
        [7081.48779297, 7079.49414062, 7071.55175781, ...,
         7578.56396484, 7580.08105469, 7581.52392578],
        [7092.57421875, 7091.46142578, 7084.03515625, ...,
         7555.39111328, 7556.4609375 , 7557.59423828]],

       [[7212.64746094, 7219.09814453, 7212.01953125, ...,
         7318.93017578, 7322.15234375, 7322.57910156],
        [7177.25439453, 7182.99804688, 7175.34472656, ...,
         7355.71191406, 7359.23193359, 7358.66357422],
        [7132.80810547, 7136.59228516, 7129.38623047, ...,
         7305.28417969, 7308.18945312, 7308.70263672],
        ...,
        [7065.79296875, 7068.30175781, 7061.06982422, ...,
         7626.03173828, 7627.05859375, 7628.70166016],
        [7002.35253906, 7001.8515625 , 6994.52783203, ...,
         7566.27490234, 7567.78955078, 7569.55566406],
        [7021.21875   , 7019.43994141, 7011.95996094, ...,
         7562.21630859, 7562.36767578, 7564.67236328]],

       [[7241.15087891, 7247.05029297, 7240.47851562, ...,
         7338.67822266, 7342.7109375 , 7344.18115234],
        [7252.63232422, 7260.09521484, 7254.09912109, ...,
         7386.73681641, 7390.64990234, 7391.64257812],
        [7145.65332031, 7149.48144531, 7142.99072266, ...,
         7308.43847656, 7312.24951172, 7313.49609375],
        ...,
        [7094.63623047, 7098.92919922, 7092.01708984, ...,
         7681.48339844, 7682.96875   , 7683.60742188],
        [7028.58642578, 7030.24316406, 7022.75292969, ...,
         7604.31152344, 7605.55322266, 7606.68066406],
        [6996.43945312, 6996.42529297, 6988.95947266, ...,
         7573.12744141, 7574.19775391, 7576.15429688]],

       ...,

       [[7036.64746094, 7037.16259766, 7045.09570312, ...,
         7229.30957031, 7226.89599609, 7229.54980469],
        [7000.76318359, 7002.78369141, 7009.23193359, ...,
         7202.43261719, 7201.7109375 , 7205.59033203],
        [7006.60400391, 7008.78710938, 7016.1171875 , ...,
         7234.43310547, 7235.27685547, 7237.71289062],
        ...,
        [6603.97363281, 6609.1796875 , 6610.92285156, ...,
         7327.31054688, 7333.40332031, 7334.15429688],
        [6541.77783203, 6544.40917969, 6547.33496094, ...,
         7202.00146484, 7209.82568359, 7210.59423828],
        [6540.33496094, 6544.27001953, 6547.78710938, ...,
         7229.359375  , 7236.43798828, 7237.23681641]],

       [[7079.18994141, 7077.49755859, 7087.25634766, ...,
         7243.95214844, 7239.84912109, 7244.13330078],
        [7030.85253906, 7030.89013672, 7039.74316406, ...,
         7245.76025391, 7243.72070312, 7246.265625  ],
        [7021.67431641, 7020.08496094, 7029.73828125, ...,
         7240.45605469, 7240.32617188, 7243.45214844],
        ...,
        [6570.17529297, 6572.94970703, 6575.56933594, ...,
         7284.13818359, 7290.47460938, 7291.52783203],
        [6497.43798828, 6496.58496094, 6500.19921875, ...,
         7155.86523438, 7164.11181641, 7165.36083984],
        [6497.15429688, 6496.859375  , 6500.12255859, ...,
         7183.61523438, 7190.92382812, 7192.05371094]],

       [[7086.27539062, 7082.92919922, 7094.92382812, ...,
         7241.73681641, 7237.0234375 , 7241.67333984],
        [7028.95214844, 7028.87646484, 7038.41113281, ...,
         7264.92236328, 7261.62597656, 7265.14648438],
        [7034.25097656, 7032.36230469, 7043.29052734, ...,
         7234.70996094, 7233.64794922, 7237.57373047],
        ...,
        [6573.10986328, 6576.46630859, 6578.87841797, ...,
         7244.41894531, 7251.1875    , 7252.89599609],
        [6504.79052734, 6503.99560547, 6507.7421875 , ...,
         7115.03808594, 7123.48291016, 7125.04638672],
        [6505.9453125 , 6503.875     , 6507.15429688, ...,
         7143.95019531, 7151.77783203, 7153.34863281]]])

In [ ]:

fiss.header

Out[ ]:

SIMPLE  =                    T /  file does conform to FITS standard            
BITPIX  =                   16 /  number of bits per data pixel                 
NAXIS   =                    3 /  number of data axes                           
NAXIS1  =                  512 /  length of data axis 1                         
NAXIS2  =                  256 /  length of data axis 2                         
NAXIS3  =                  130 /  length of data axis 3                         
DATE    = '2014-06-03T17:08:41' /  file creation date (YYYY-MM-DDThh:mm:s       
EXPTIME =                 0.03 /  Second                                        
HBINNING=                    1                                                  
VBINNING=                    2                                                  
GAIN    =                    0 /  Value Range: 0-255                            
STRTIME = '2014.06.03-17:08:24' /  Scan Start Time                              
ENDTIME = '2014.06.03-17:08:41' /  Scan Finish Time                             
ELAPTIME=             17.33194 /  Elapse Time During Scanning(Second)           
FISSMODE= 'Spectrograph'       /  FISS Mode                                     
STEPTIME=                130.0 /  1 Step Duration time(millisecond)             
STEPSIZE=         4.484155E-44 /  1 step size to move scanner(micrometer)       
CCDTEMP =                  -28 /  Cooling Temperature of CCD                    
CCDNAME = 'DV897_BV'           /  Productname of CCD                            
WAVELEN = '6562.8  '           /  CCD1 Wavenength(angstrom)                     
CCD_XPIX=                  512 /  Full Pixel Size of X                          
CCD_YPIX=                  512 /  Full Pixel Size of Y                          
OBSERVER= 'Donguk Song'        /  The Name of Main Observer                     
TARGET  = 'Sunspot '           /  Observation Target                            
TEL_XPOS=                  134 /  X position of Telescope on the Sun            
TEL_YPOS=                 -318 /  Y position of Telescope on the Sun            
CRPIX1  =        259.848724365 /  pixel position of reference line center       
CDELT1  =      0.0191817938094 / angstrom per pixel                             
CRVAL1  =             6562.817 / angstrom of reference line center              
HISTROY = 'processed by FISS_PREP'                                              
HISTORY dark+bias subtracted                                                    
HISTORY flat-fieldded                                                           
HISTORY -0.28 degree tilt corrected                                             
HISTORY displacement/distortion corrected

When you read the FISS data without any optional keyword, the wavelength will be calibrated using the information in the fits header. This calibration method always works, but it does not reflect the instrumental or time-varying shift of the line profile. Hence, we recommend recalibrating the wavelength using wvCalib with the method keyword of either 'center' or 'photo'.

In [ ]:

fiss.wave = fiss.wvCalib(method='photo')
print(fiss.wave[250-5:250+5])

[6562.50901164 6562.52811525 6562.54721886 6562.56632247 6562.58542608
 6562.60452969 6562.6236333  6562.64273691 6562.66184052 6562.68094413]

You can correct the stray light and line asymmetry using the 'corSLA' method.

In [ ]:

fiss.corSLA()

You can smooth the spectral profile using the 'smoothingProf'.

In [ ]:

fiss.smoothingProf()

If you want to reset the data, you can reload the data using the 'reload'.

In [ ]:

fiss.reload

Now we draw the quick look interactive figure for the raster and spectral profile. For this we use '.imshow' method.

Note that if you run the interactive figure, you should change the matplotlib backend first:

In [ ]:

%matplotlib

Using matplotlib backend: <object object at 0x0000025F4F9EF550>

In [ ]:

fiss.imshow()

No description has been provided for this image

If you do not set the help box keyword to False, two figures will pop up: one is the main figure, and another is the help box for the interactive keys.

Following the help box figure or the below table for interactive keys, you can select or adjust the pixel point to change the raster image or profile.

Keys	Description
ctrl/cmd+h	Return to original setting position.
right	Change the spectrograph and profile at the pixel of x+1.
left	Change the spectrograph and profile at the pixel of x-1.
up	Change the profile at the pixel of y+1.
down	Change the profile at the pixel of y-1.
ctrl/cmd+right	Show the raster image with λ+1.
ctrl/cmd+left	Show the raster image with λ-1.
spacebar	Show the raster image with λ-1.
ctrl/cmd+b	Show the previous point. It is used to blink between two points.

This module is combined with the lambdameter function, so you can easily draw the line-of-sight Doppler map, using the 'vshow' method.

In [ ]:

fiss.vshow(hw=0.2)
fiss.chVclim(-5,5)

/Users/jhkang/miniforge3/envs/fisspydocs/lib/python3.9/site-packages/fisspy/read/read_factory.py:613: UserWarning: FigureCanvasAgg is non-interactive, and thus cannot be shown
  self.fig.show()

For details of the attributes and methods please see fisspy.read.FISS document page.

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