9_Practical/pimaging.ipynb

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    "<center>\n",
    "<h1 class=\"title\">Imaging</h1>\n",
    "\n",
    "<h2>S.K. Sirothia</h2>\n",
    "<h3>RARG, SKA-SA</h3>\n",
    "<h3>NASSP Radio Interferometry Practical</h3>\n",
    "</center>"
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    "# Check the msfile\n",
    "\n",
    "    #Set up some useful variables\n",
    "    prefix = '3gc4_prac_01'\n",
    "    srcsplitms = '3gc4_prac_01.src.split.ms'\n",
    "\n",
    "    vis = srcsplitms\n",
    "    listobs()"
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    "## The listobs output on casa logger window\n",
    "![image](fig_pimag/list_obs.png)"
   ]
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    "\n",
    "<center>\n",
    "\n",
    "<h1 class=\"title\">Imaging mode 'Channel'</h1>\n",
    "\n",
    "</center>\n"
   ]
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    "# CASA task CLEAN (Make the dirty image)\n",
    "    \n",
    "    default('clean')                     #Set the clean defaults\n",
    "    vis = srcsplitms                     #Pick up our split source data\n",
    "    dirtyname = prefix + '.dirtyimg'     #Make an image root file name\n",
    "    imagename = dirtyname\n",
    "\n",
    "    mode = 'channel'                     #Setting the parameters related to imaging\n",
    "    nchan = 72                           #Set up the output image cube\n",
    "    start = 1\n",
    "    width = 1\n",
    "    \n",
    "    field = '0'                          #Set the field to image\n",
    "    spw = ''                             #Set the spectral window to image\n",
    "    \n",
    "    imsize = [256,256]                   #Set the image size\n",
    "    cell = [45.,45.]                     #Pixel size 45 arcsec for this KAT7 data\n",
    "\n",
    "    weighting = 'briggs'                 #Set the visibility weighting scheme\n",
    "    robust = 0.5\n",
    "    \n",
    "    niter = 0                            #No cleaning since we are making the dirtly image\n",
    "    inp()                                #Check the inputs\n",
    "\n",
    "    clean()                              #Run the task clean to make the dirtly image\n",
    "    \n",
    "    dirtyimage = dirtyname+'.image'      #Check the image\n",
    "    viewer(dirtyimage)"
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   "source": [
    "## Clean log, in the casa shell window \n",
    "![image](fig_pimag/inp_dirtyimage_clean.png)"
   ]
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   "source": [
    "## Checking the inputs, in the casa logger window \n",
    "![image](fig_pimag/clean_dirtyimage_casa_logger.png)"
   ]
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   "source": [
    "## Dirty image in the casa viewer window\n",
    "![image](fig_pimag/viewer_dirtyimage.png)"
   ]
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   "source": [
    "# CASA task CLEAN (Make the clean image)\n",
    "\n",
    "    default('clean')                     #Set the clean defaults\n",
    "    vis = srcsplitms                     #Pick up our split source data\n",
    "    imname = prefix + '.cleanimg'        #Make an image root file name\n",
    "    imagename = imname\n",
    "\n",
    "    mode = 'channel'                     #Setting the parameters related to imaging\n",
    "    nchan = 72                           #Set up the output image cube\n",
    "    start = 1\n",
    "    width = 1\n",
    "\n",
    "    field = '0'                          #Set the field to image (This is a single-source MS with one spw)\n",
    "    spw = ''                             #Set the spectral window to image\n",
    "    imsize = [256,256]                   #Set the image size\n",
    "    cell = [45.,45.]                     #Pixel size 45 arcsec for this KAT7 data\n",
    "\n",
    "    gain = 0.1                           #Standard gain factor 0.1\n",
    "    psfmode = 'clark'                    #Do a simple Clark clean\n",
    "    csclean = False                      #No Cotton-Schwab iterations\n",
    "    #imsize = [512,512]                  #Twice as big for Cotton-Schwab (cleans inner quarter)\n",
    "    #csclean = True                      #If desired, you can do a Cotton-Schwab clean \n",
    "                                         #but will have only marginal improvement for this data\n",
    "\n",
    "    niter = 6000                         #Fix maximum number of iterations\n",
    "    threshold=10.0                       #Also set flux residual threshold (in mJy)\n",
    "\n",
    "    weighting = 'briggs'                 #Set the visibility weighting scheme\n",
    "    robust = 0.5                         #Use Briggs weighting (a moderate value, on the uniform side)\n",
    "\n",
    "    #mask = [108,108,148,148]            #Set a cleanbox +/-20 pixels around the center 128,128\n",
    "    mask = ''                            #If you don't want any clean boxes or masks\n",
    "\n",
    "    interactive=False                    #If you want interactive clean set to True\n",
    "\n",
    "    inp()                                #Check the inputs\n",
    "    clean()                              #Run the task clean to make the dirtly image\n",
    "\n",
    "    clnimage = imname+'.image'           #Check the image\n",
    "    viewer(clnimage)"
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   "source": [
    "## Clean log, in the casa shell window \n",
    "![image](fig_pimag/inp_cleanimage_clean.png)"
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   "source": [
    "## Checking the inputs, in the casa logger window \n",
    "![image](fig_pimag/clean_cleanimage_casa_logger.png)"
   ]
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   "source": [
    "## Clean image in the casa viewer window\n",
    "![image](fig_pimag/viewer_cleanimage.png)"
   ]
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    "\n",
    "<center>\n",
    "\n",
    "<h1 class=\"title\">Imaging mode 'mfs'</h1>\n",
    "\n",
    "</center>\n"
   ]
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    "# CASA task CLEAN (Make the dirty image mode=mfs)\n",
    "    \n",
    "    default('clean')                     #Set the clean defaults\n",
    "    vis = srcsplitms                     #Pick up our split source data\n",
    "    dirtyname = prefix + '.dirtyimg'     #Make an image root file name\n",
    "    imagename = dirtyname\n",
    "    \n",
    "    os.system('rm -rf '+imagename+'*')   #remove previous version of these images\n",
    "    \n",
    "    mode = 'mfs'                         #Setting the parameters related to imaging\n",
    "    nchan = 72                           #Set up the output image cube\n",
    "    start = 1\n",
    "    width = 1\n",
    "    \n",
    "    field = '0'                          #Set the field to image\n",
    "    spw = ''                             #Set the spectral window to image\n",
    "    \n",
    "    imsize = [256,256]                   #Set the image size\n",
    "    cell = [45.,45.]                     #Pixel size 45 arcsec for this KAT7 data\n",
    "\n",
    "    weighting = 'briggs'                 #Set the visibility weighting scheme\n",
    "    robust = 0.5\n",
    "    \n",
    "    niter = 0                            #No cleaning since we are making the dirtly image\n",
    "    inp()                                #Check the inputs\n",
    "\n",
    "    clean()                              #Run the task clean to make the dirtly image\n",
    "    \n",
    "    dirtyimage = dirtyname+'.image'      #Check the image\n",
    "    viewer(dirtyimage)"
   ]
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   "source": [
    "## Dirty image (mode=mfs) in the casa viewer window\n",
    "![image](fig_pimag/viewer_dirtyimagemfs.png)"
   ]
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    "# CASA task CLEAN (Make the clean image, mode=mfs)\n",
    "\n",
    "    default('clean')                     #Set the clean defaults\n",
    "    vis = srcsplitms                     #Pick up our split source data\n",
    "    imname = prefix + '.cleanimg'        #Make an image root file name\n",
    "    imagename = imname\n",
    "\n",
    "    os.system('rm -rf '+imagename+'*')   #remove previous version of these images\n",
    "\n",
    "    mode = 'mfs'                         #Setting the parameters related to imaging\n",
    "    nchan = 72                           #Set up the output image cube\n",
    "    start = 1\n",
    "    width = 1\n",
    "\n",
    "    field = '0'                          #Set the field to image (This is a single-source MS with one spw)\n",
    "    spw = ''                             #Set the spectral window to image\n",
    "    imsize = [256,256]                   #Set the image size\n",
    "    cell = [45.,45.]                     #Pixel size 45 arcsec for this KAT7 data\n",
    "\n",
    "    gain = 0.1                           #Standard gain factor 0.1\n",
    "    psfmode = 'clark'                    #Do a simple Clark clean\n",
    "    csclean = False                      #No Cotton-Schwab iterations\n",
    "    #imsize = [512,512]                  #Twice as big for Cotton-Schwab (cleans inner quarter)\n",
    "    #csclean = True                      #If desired, you can do a Cotton-Schwab clean \n",
    "                                         #but will have only marginal improvement for this data\n",
    "\n",
    "    niter = 6000                         #Fix maximum number of iterations\n",
    "    threshold=10.0                       #Also set flux residual threshold (in mJy)\n",
    "\n",
    "    weighting = 'briggs'                 #Set the visibility weighting scheme\n",
    "    robust = 0.5                         #Use Briggs weighting (a moderate value, on the uniform side)\n",
    "\n",
    "    #mask = [108,108,148,148]            #Set a cleanbox +/-20 pixels around the center 128,128\n",
    "    mask = ''                            #If you don't want any clean boxes or masks\n",
    "\n",
    "    interactive=False                    #If you want interactive clean set to True\n",
    "\n",
    "    inp()                                #Check the inputs\n",
    "    clean()                              #Run the task clean to make the dirtly image\n",
    "\n",
    "    clnimage = imname+'.image'           #Check the image\n",
    "    viewer(clnimage)"
   ]
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   "source": [
    "## Clean image (mode=mfs) in the casa viewer window\n",
    "![image](fig_pimag/viewer_cleanimagemfs.png)"
   ]
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