Difference between revisions of "PPdisk simdata (CASA 3.1)"

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{{Simulations Intro 3.1}}
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[[Category: Simulations]]
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== Protoplanetary disk ==
 
== Protoplanetary disk ==
[ftp://ftp.cv.nrao.edu/NRAO-staff/rindebet/input50pc_672GHz.fits this fits file] is a model of a protoplanetary disk from S. Wolf.  ** If you use it for anything more than learning CASA, please cite [http://adsabs.harvard.edu/abs/2005ApJ...619.1114W Wolf & D'Angelo 2005].
+
*[ftp://ftp.cv.nrao.edu/NRAO-staff/rindebet/input50pc_672GHz.fits This fits file] is a model of a protoplanetary disk from S. Wolf (If you use it for anything more than learning CASA, please cite [http://adsabs.harvard.edu/abs/2005ApJ...619.1114W Wolf & D'Angelo 2005]).
 +
 
 +
*Simdata version for CASA 3.1
 +
__NOTOC__
 +
<br>
 +
====Explanation of the script====
 +
 
 +
=====Set simdata as current task and reset all parameters=====
 +
  default("simdata") 
 +
=====Specify sky model image=====
 +
  modelimage        =  "input50pc_672GHz.fits" 
 +
=====Image coordinate system can be verified=====
 +
  imhead("input50pc_672GHz.fits") 
 +
=====Image center can be identified=====
 +
  # ia.open("input50pc_672GHz.fits")
 +
  # ia.shape()
 +
  # [257L, 257L, 1L, 1L]
 +
  # ia.toworld([128.5,128.5])
 +
  # {'numeric': array([  4.71239120e+00,  -4.01423802e-01,  1.00000000e+00,  6.72000001e+11])}
 +
  # qa.formxxx("4.71239120rad",format='hms',prec=5)
 +
  # '18:00:00.03052'
 +
  # qa.formxxx("-0.401423802rad",format='dms',prec=5)
 +
  # '-022.59.59.602743'
 +
  # ia.done()
 +
=====Brightness scale can be viewed with 'imstat' task=====
 +
  # imstat("input50pc_672GHz.fits")
 +
  # ...
 +
  #  'max': array([  6.52469971e-05]),
 +
  # ...
 +
  # that's 0.0652 mJy/pixel. 
 +
=====Let's leave the brightness of the image as it is=====
 +
  inbright          =  "unchanged" 
 +
=====Let's call our project psim2=====
 +
  project            =  "psim2" 
 +
=====We'll leave the sky model the way it is: simdata will create psim2.skymodel CASA image since this model is a fits file, and most but not all of CASA routines can operate directly on fits=====
 +
  modifymodel        =  False 
 +
  skymodel          =  "input50pc_672GHz.fits" 
 +
=====We need to decide where to point the telescope.  The image is 2/3 arcsec in size, so we only need one pointing. We could put that in a text file ourself, or let simdata create the ascii pointing file for us.=====
 +
  setpointings      =  True
 +
  direction          =  "J2000 18h00m00.031s -22d59m59.6s"
 +
  mapsize            =  "0.76arcsec" 
 +
=====The default pointingspacing is fine: we'll only fit one pointing in the small mapsize the default calculation maptype hexagonal is ok too since only one will fit anyway.=====
 +
 
 +
=====We do want to calculate visibilities in a measurement set: let's do a 20 min snapshot observation using out20 configuration:=====
 +
  predict            =  True
 +
  totaltime          =  "1200s"
 +
 
 +
=====Use appropriate antenna configurations based on desired angular resolution=====
 +
  repodir=os.getenv("CASAPATH").split(' ')[0]
 +
  antennalist        =  repodir+"/data/alma/simmos/alma.out20.cfg" 
 +
=====Deconvolve the visibilities back into an image=====
 +
  image              =  True
 +
  vis                =  "$project.ms"
 +
  imsize            =  [192, 192] 
 +
=====Specify number of iteration of cleaning task with proper threshold and weighting=====
 +
  niter              =  10000
 +
  threshold          =  "1e-7Jy"
 +
  weighting          =  "natural"   
 +
=====We'd like to calculate a difference and fidelity image, and see some diagnostics:=====
 +
  analyze            =  True 
 +
=====And see the array but not the UV coverage:=====
 +
  showarray          =  True
 +
  showuv            =  False 
 +
=====Plot both to the screen and the png files with lots of messages:=====
 +
  graphics          =  "both"
 +
  verbose            =  True
 +
  overwrite = True
 +
 
 +
===To run the script ===
 +
 
 +
  CASA<> execfile("Ppdisk.simdata.txt")
 +
 
 +
  CASA<> go simdata
 +
 
 +
<br>
 +
*Output results:
  
simdata2 version of script and output: [[File:Ppdisk.simdata2.txt]]
 
  
[[File:Psim2.skymodel.png|300px]]
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{| style="border:1px solid #3366FF; " cellspacing=2
[[File:Psim2.predict.png|300px]]
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|Input:<br> [[File:Psim2.skymodel.png|300px]]
[[File:Psim2.image.png|300px]]
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|Predict:<br> [[File:Psim2.predict.png|300px]]
[[File:Psim2.analysis.png|300px]]
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|-
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|Image:<br> [[File:Psim2.image.png|300px]]
 +
|Analyze:<br> [[File:Psim2.analysis.png|300px]]
 +
|}

Latest revision as of 18:28, 28 April 2011

Simulating Observations in CASA 3.1

Protoplanetary disk

  • Simdata version for CASA 3.1


Explanation of the script

Set simdata as current task and reset all parameters
 default("simdata")   
Specify sky model image
 modelimage         =  "input50pc_672GHz.fits"  
Image coordinate system can be verified
 imhead("input50pc_672GHz.fits")  
Image center can be identified
 # ia.open("input50pc_672GHz.fits")
 # ia.shape()
 # [257L, 257L, 1L, 1L]
 # ia.toworld([128.5,128.5])
 # {'numeric': array([  4.71239120e+00,  -4.01423802e-01,   1.00000000e+00,  6.72000001e+11])}
 # qa.formxxx("4.71239120rad",format='hms',prec=5)
 # '18:00:00.03052'
 # qa.formxxx("-0.401423802rad",format='dms',prec=5)
 # '-022.59.59.602743'
 # ia.done()
Brightness scale can be viewed with 'imstat' task
 # imstat("input50pc_672GHz.fits")
 # ...
 #  'max': array([  6.52469971e-05]),
 # ...
 # that's 0.0652 mJy/pixel.   
Let's leave the brightness of the image as it is
 inbright           =  "unchanged"  
Let's call our project psim2
 project            =  "psim2"  
We'll leave the sky model the way it is: simdata will create psim2.skymodel CASA image since this model is a fits file, and most but not all of CASA routines can operate directly on fits
 modifymodel        =  False  
 skymodel           =  "input50pc_672GHz.fits"   
We need to decide where to point the telescope. The image is 2/3 arcsec in size, so we only need one pointing. We could put that in a text file ourself, or let simdata create the ascii pointing file for us.
 setpointings       =  True
 direction          =  "J2000 18h00m00.031s -22d59m59.6s"
 mapsize            =  "0.76arcsec"  
The default pointingspacing is fine: we'll only fit one pointing in the small mapsize the default calculation maptype hexagonal is ok too since only one will fit anyway.
We do want to calculate visibilities in a measurement set: let's do a 20 min snapshot observation using out20 configuration:
 predict            =  True
 totaltime          =  "1200s"
Use appropriate antenna configurations based on desired angular resolution
 repodir=os.getenv("CASAPATH").split(' ')[0]
 antennalist        =  repodir+"/data/alma/simmos/alma.out20.cfg"  
Deconvolve the visibilities back into an image
 image              =  True
 vis                =  "$project.ms"
 imsize             =  [192, 192]  
Specify number of iteration of cleaning task with proper threshold and weighting
 niter              =  10000
 threshold          =  "1e-7Jy"
 weighting          =  "natural"    
We'd like to calculate a difference and fidelity image, and see some diagnostics:
 analyze            =  True  
And see the array but not the UV coverage:
 showarray          =  True
 showuv             =  False  
Plot both to the screen and the png files with lots of messages:
 graphics           =  "both"
 verbose            =  True
 overwrite = True

To run the script

 CASA<> execfile("Ppdisk.simdata.txt")
 CASA<> go simdata


  • Output results:


Input:
Psim2.skymodel.png
Predict:
Psim2.predict.png
Image:
Psim2.image.png
Analyze:
Psim2.analysis.png