Difference between revisions of "Setjy"

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Revision as of 15:43, 16 March 2012

Help on setjy task:

Fills the model column with the visibility of a calibrator

       The task places the model visibility amp and phase associated
       with a specified source (generally a calibrator).
       The simplest way to to enter the flux density
       (I,Q,U,V) explicitly, but this is valid only for a point source.

       For an extended source, the clean model (image.model) can be
       specified and the model visibilities associated with this clean
       model is placed in the visibility model column.

       Models are available for 3C48, 3C138, 3C286 between
       1.4 and 43 GHz.  3C147 is available above 13 GHz.  These models
       are scaled to the precise frequency of the data.  Only I source 
       model can be inserted at a time.

       The location of the models are system dependent:  At the AOC and CV,
       the models are in the directory::/usr/lib/casapy/data/nrao/VLA/CalModels
       or /usr/lib64/casapy/data/nrao/VLA/CalModel.

       Setjy need only be run on the calibrator sources with a know flux
       density and/or model.

       Keyword arguments:
       vis -- Name of input visibility file
               default: none.  example: vis='ngc5921.ms'
       field -- Select field using field id(s) or field name(s).
              default: ''=all fields, but run setjy one field at a time.
                 [run listobs to obtain the list id's or names of calibrators]
              If field string is a non-negative integer, it is assumed a field index
                otherwise, it is assumed a field name
              field='0~2'; field ids 0,1,2
              field='0,4,5~7'; field ids 0,4,5,6,7
              field='3C286,3C295'; field named 3C286 adn 3C295
              field = '3,4C*'; field id 3, all names starting with 4C
       spw -- Select spectral window/channels
              default: ''=all spectral windows and channels
              spw='0~2,4'; spectral windows 0,1,2,4 (all channels)
              spw='<2';  spectral windows less than 2 (i.e. 0,1)
              spw='0:5~61'; spw 0, channels 5 to 61
              spw='0,10,3:3~45'; spw 0,10 all channels, spw 3, channels 3 to 45.
              spw='0~2:2~6'; spw 0,1,2 with channels 2 through 6 in each.
              spw='0:0~10;15~60'; spectral window 0 with channels 0-10,15-60
              spw='0:0~10,1:20~30,2:1;2;4'; spw 0, channels 0-10,
                       spw 1, channels 20-30, and spw 2, channels, 1,2 and 4
              field='3C286,3C295'; field named 3C286 adn 3C295
              field = '3,4C*'; field id 3, all names starting with 4C
       spw -- Select spectral window/channels
              default: ''=all spectral windows and channels
              spw='0~2,4'; spectral windows 0,1,2,4 (all channels)
              spw='<2';  spectral windows less than 2 (i.e. 0,1)
              spw='0:5~61'; spw 0, channels 5 to 61
              spw='0,10,3:3~45'; spw 0,10 all channels, spw 3, channels 3 to 45.
              spw='0~2:2~6'; spw 0,1,2 with channels 2 through 6 in each.
              spw='0:0~10;15~60'; spectral window 0 with channels 0-10,15-60
              spw='0:0~10,1:20~30,2:1;2;4'; spw 0, channels 0-10,
                       spw 1, channels 20-30, and spw 2, channels, 1,2 and 4

       Use one of the two methods below:  modimage or fluxdensity

       modimage -- Model image (I only) from which the model visibilities
              default: '' means do not use model, but fluxdensity
              Each field must be done separately.  The image clean model
              will be scaled from the frequency in the model to that actually used.
              Both the amplitude and phase are calculated.
              At the AOC or CV, the models are located in the
              /usr/lib/casapy/data/nrao/VLA/CalModels/3C286_L.im (egs)
                   lib64

       fluxdensity -- Specified flux density [I,Q,U,V] in Jy
               default => -1, places [1,0,0,0] flux density for all sources,
                  except for 3C286, 3C48 and 3C147 where the absolute flux
                  density it added.  It is recommended to use the modimage for
                  these sources if they are resolved with the observations.
               Only one flux density can be executed at a time.  The phases are
                  set to zero.
               example   fluxdensity=-1  will insert 1.0 for all calibrators
                         except 3C286, 3C147 and 3C48
               example   field = '1'; fluxdensity=[3.2,0,0,0] wil put in 
                         flux density of I=3.2 for field='1'

               At present, this is the only method to insert a polarized flux
               density model (June 2000).
               example:  fluxdensity=[2.63,0.21,-0.33,0.02]
                         will put in I,Q,U,V flux densities of 2.63,0.21,-0.33,
                         and 0.02, respectively, in the model column.

       standard -- Flux density standard, used if fluxdensity<0
               default: 'Perley-Taylor 99'; example: standard='Baars'
               Options: 'Baars','Perley 90','Perley-Taylor 95',
                  'Perley-Taylor 99'