PPdisk simdata (CASA 3.2)
From CASA Guides
↵ Simulating Observations in CASA 3.1
Protoplanetary disk
- 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 Wolf & D'Angelo 2005).
- 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:
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Predict:
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Image:
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Analyze:
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