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def | __init__ |
def | __call__ |
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__doc__ | |
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string | __name__ |
Definition at line 18 of file simobserve_pg.py.
def simobserve_pg.simobserve_pg_.__init__ | ( | self | ) |
Definition at line 21 of file simobserve_pg.py.
def simobserve_pg.simobserve_pg_.__call__ | ( | self, | |
project = None , |
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skymodel = None , |
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inbright = None , |
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indirection = None , |
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incell = None , |
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incenter = None , |
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inwidth = None , |
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complist = None , |
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compwidth = None , |
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setpointings = None , |
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ptgfile = None , |
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integration = None , |
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direction = None , |
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mapsize = None , |
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maptype = None , |
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pointingspacing = None , |
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caldirection = None , |
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calflux = None , |
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obsmode = None , |
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refdate = None , |
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hourangle = None , |
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totaltime = None , |
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antennalist = None , |
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sdantlist = None , |
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sdant = None , |
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thermalnoise = None , |
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user_pwv = None , |
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t_ground = None , |
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t_sky = None , |
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tau0 = None , |
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seed = None , |
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leakage = None , |
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graphics = None , |
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verbose = None , |
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overwrite = None , |
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async = None |
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) |
mosaic simulation task mosaic simulation task: This task simulates interferometric observations (currently only ALMA can be done easily). New functionality is actively being added, so if you have changed versions of CASA, check the inputs carefully. More information and examples are availible at http://casaguides.nrao.edu/index.php?title=Simulating_Observations_in_CASA Please contact CASA experts with any questions, especially about features noted below as *experimental* ------------------------------- project -- root filename for all output files. ------------------------------- skymodel -- image model of the sky in FITS or CASA image, with optional parameters that can be overridden inbright -- peak brightness in Jy/pixel, or "" for unchanged * NOTE: "unchanged" will take the numerical values in your image and assume they are in Jy/pixel, even if it says some other unit in the header. indirection -- central direction, or "" for unchanged incell -- spatial pixel size, or "" for unchanged incenter -- frequency of center channel e.g. "89GHz", or "" for unchanged inwidth -- width of channels, or "" for unchanged - this should be a string representing a quantity with units e.g. "10MHz" * NOTE: only works reliably with frequencies, not velocities * NOTE: it is not possible to change the number of spectral planes of the sky model, only to relabel them with different frequencies That kind of regridding can be accomplished with the CASA toolkit. ------------------------------- complist -- component list model of the sky, added to or instead of skymodel compwidth -- bandwidth of components; if simulating from components only, this defines the bandwidth of the MS and output images ------------------------------- setpointings -- calculate a map of pointings, or if false, provide ptgfile * if graphics are on, display the pointings shown on the model image ptgfile -- a text file specifying directions in the following format, with optional integration times, e.g. #Epoch RA DEC TIME(optional) J2000 23h59m28.10 -019d52m12.35 10.0 * if the time column is not present in the file, it will use "integration" for all pointings. * NOTE: at this time the file should contain only science pointings: simobserve will observe these, then optionally the calibrator, then the list of science pointings again, etc, until totaltime is used up. integration --- Time interval for each integration e.g '10s' * NOTE: to simulate a "scan" longer than one integration, use setpointings to generate a pointing file, and then edit the file to increase the time at each point to be larger than the parameter integration time. direction -- mosaic center direction e.g 'J2000 19h00m00 -40d00m00' * can optionally be a list of pointings * otherwise simobserve will pack mapsize according to maptype mapsize -- angular size of map * set to "" to span the model image maptype -- hexagonal, square (rectangular raster), "ALMA" for the same hex algorithm as the ALMA OT or "ALMA2012" for the algorithm used in the Cycle 0 OT pointingspacing -- spacing in between beams e.g '1arcsec' or "0.25PB" to use 1/4 of the primary beam FWHM, or "" will use Nyquist spacing, lambda/d/sqrt(3). ------------------------------- obsmode -- observation mode to calculate visibilities from skymodel (which may have been modified above, (optionally) complist, and $ptgfile (which may have been generated above) * this parameter takes two possible values: - interferometer (or i) - singledish (or s) * if graphics are on, display the array (like plotants), the uv coverage, the synthesized (dirty) beam, and ephemeris information * if simulating from component list, you should specify compwidth, the desired bandwidth - there is not currently a way to specify the spectrum of a component, so simulations from a componentlist only will be continuum (1 chan) refdate -- date of simulated observation eg: '2014/05/21' hourangle -- hour angle of observation e.g. '-3h' totaltime --- total time of observation e.g '7200s' or if a number without units, interpreted as the number of times to repeat the map antennalist -- ascii file containing antenna positions. each row has x y z coordinates and antenna diameter; header lines are required to specify the observatory name and coordinate system e.g. # observatory=ALMA # coordsys=UTM # datum=WGS84 # zone=19 * standard arrays are found in your CASA data repository, os.getenv("CASAPATH").split()[0]+"/data/alma/simmos/" * if "", will not not produce an interferometric MS * a string of the form "alma;0.5arcsec" will be parsed into a full 12m ALMA configuration. This only works for full ALMA and may fail to find the standard configuration files on some systems - see casaguides.nrao.edu caldirection -- *NEW* an unresolved calibrator can be observed interleaved with the science pointings. This feature is experimental, so please contact us with any questions. * The calibrator is implemented as a point source clean component with this direction and flux=calflux sdant -- the index of the antenna in the list to use for total power. defaults to the first antenna on the list. ------------------------------- thermalnoise -- add thermal noise * this parameter takes two possible values: - tsys-atm: J. Pardo's ATM library will be used to construct an atmospheric profile for the ALMA site: altitude 5000m, ground pressure 650mbar, relhum=20%, a water layer of user_pwv at altitude of 2km, the sky brightness temperature returned by ATM, and internally tabulated receiver temperatures - tsys-manual: instead of using the ATM model, specify the zenith sky brightness and opacity manually. Noise is added and then the visibility flux scale is referenced above the atmosphere. * In either mode, noise is calculated using an antenna spillover efficiency of 0.96, taper of 0.86, surface accuracy of 25 and 300 microns for ALMA and EVLA respectively (using the Ruze formula for surface efficiency), correlator efficiencies of 0.95 and 0.91 for ALMA and EVLA, receiver temperatures for ALMA of 17, 30, 37, 51, 65, 83,147,196,175,230 K interpolated between 35, 75,110,145,185,230,345,409,675,867 GHz, for EVLA of 500, 70, 60, 55, 100, 130, 350 K interpolated between 0.33,1.47,4.89,8.44,22.5,33.5,43.3 GHz, for SMA of 67, 116, 134, 500 K interpolated between 212.,310.,383.,660. GHz * These are only approximate numbers and do not take into account performance at edges of receiver bands, neither are they guaranteed to reflect the most recent measurements. Caveat emptor and use the sm tool to add noise if you want more precise control. t_ground -- ground/spillover temperature in K user_pwv -- precipitable water vapor if constructing an atmospheric model t_sky -- atmospheric temperature in K [for tsys-manual] tau0 -- zenith opacity at observing frequency [for tsys-manual] * see casaguides.nrao.edu for more information on noise, in particular how to add a phase screen using the toolkit seed -- random number seed for noise generation ------------------------------- leakage -- add cross polarization corruption of this fractional magnitude graphics -- view plots on the screen, saved to file, both, or neither verbose -- print extra information to the logger and terminal overwrite -- overwrite existing files in the project subdirectory ------------------------------- How to specify a model image: ------------------------------- * simobserve requires a CASA or fits image. If you merely have a grid of numbers, you will need to write them out as fits or write a CASA script to read them in and use the ia tool to create an image and insert the data. * simobserve does NOT require a coordinate system in the header. If the coordinate information is incomplete, missing, or you would like to override it, set the appropriate "in" paremeters. In the absence of other information, simobserve will assume that the axes of your input correspond to RA, Dec, and (optionally) frequency and (optionally) Stokes parameter. * If you have a proper Coordinate System, simobserve will do its best to generate visibilities from that, and then create a synthesis image according to the specified user parameters. Regridding the spectral dimension may not have complete flexibility yet. * You can manipulate an image header with the "imhead" task, or you can delve deeper with the ia and cs tools. If you use the tools, you should be aware that a CoordinateSystem in CASA can exist independently of an Image. Once the CoordinateSystem is detached from the image, it is the user's responsibility to do any manipulation e.g. axis reordering on both. Example: ia.open("myimage_filename") ia.summary() # see header as attached to the image csys=ia.coordsys() # detach the CoordinateSystem csys.summary() # examine it csys.setreferencepixel([100,100]) arr=ia.getchunk() # get the data from the Image ia.done() csys.reorder([0,2,1]) # reorder the CoordinateSystem arr=arr.reorder([0,2,1]) # reorder the data ia.fromshape(outfile="mynewimage_file",shape=[32,32,256],csys=csys.torecord(),overwrite=True) # make a new image, with the right shape and CoordinateSystem ia.putchunk(arr) # put the data into the new image. csys.done() ia.done() ------------------------------- Output produced: (not all will always exist, depending on input parameters) To support different runs with different arrays, the names have the configuration name from antennalist appended. ------------------------------- project.[cfg].skymodel = 4d input sky model image (optionally) scaled project.[cfg].skymodel.flat.regrid.conv = input sky regridded to match the output image, and convolved with the output clean beam project.[cfg].skymodel.png = diagnostic figure of sky model with pointings project.[cfg].ptg.txt = list of mosaic pointings project.[cfg].quick.psf = psf calculated from uv coverage project.[cfg].ms = noise-free measurement set project.[cfg].noisy.ms = corrupted measurement set project.[cfg].observe.png = diagnostic figure of uv coverage and visibilities project.[cfg].simobserve.last = saved input parameters for simobserve task
Definition at line 26 of file simobserve_pg.py.
References vla_uvfits_line_sf.verify.
simobserve_pg.simobserve_pg_.__bases__ [private] |
Definition at line 22 of file simobserve_pg.py.
simobserve_pg.simobserve_pg_.__doc__ [private] |
Definition at line 23 of file simobserve_pg.py.
string simobserve_pg.simobserve_pg_.__name__ [static, private] |
Definition at line 19 of file simobserve_pg.py.