NRAO Home > CASA > CASA Toolkit Reference Manual
imager.setjy - Function

2.3.1 Compute the model visibility for a specified source flux density


Description

Compute the model visibility for a specified source flux density, and insert into the MODEL_DATA column. The source flux density for a set of standard flux density reference sources may optionally be pre-computed, by setting the input flux density to -1 (the default). At present, these include 3C286, 3C48, 3C147, 3C138, and 1934-638. In this case, if the source is not in this set, an unpolarized flux density of 1 Jy will be assumed. Users may also specify standard=’SOURCE’ to use the model(s) in the SOURCE_MODEL column of the SOURCE subtable.

Users may also specify a model image that will be scaled to the specified total flux density (or that computed for reference sources). When a model image is specified, setjy will only permit processing one field, and will currently only process Stokes I.

Arguments





Inputs

field

Field Id (0-relative) or name

allowed:

any

Default:

variant

spw

Spectral Window Id. (0-relative)

allowed:

any

Default:

variant

modimage

A model image

allowed:

string

Default:

fluxdensity

Specified flux density (I,Q,U,V) in Jy (lookup the value; use 1.0 if not found)

allowed:

doubleArray

Default:

0.0 0.0 0.0 0.0

standard

Flux density standard

allowed:

string

Default:

Baars

Perley 90

Perley-Taylor 95

Perley-Taylor 99

Perley-Butler 2010

SOURCE

scalebychan

Do the flux scaling on a per channel basis else on a spw basis. Effectively True if fluxdensity is specified.

allowed:

bool

Default:

false

spix

Spectral index for fluxdensity. S = fluxdensity * (freq/reffreq)**spix

allowed:

doubleArray

Default:

0.0

reffreq

Reference frequency for spix.

allowed:

any

Default:

variant 1GHz

polindex

Coefficients for Taylor expansion of Polarization index

allowed:

doubleArray

Default:

0.0

polangle

Coefficients for Taylor expansion of Polarization angle in radians

allowed:

doubleArray

Default:

0.0

rotmeas

rotation measure (rad/lambda**2)

allowed:

double

Default:

0.0

time

Time range to operate on

allowed:

string

Default:

scan

Scan(s) to operate on

allowed:

string

Default:

intent

Observation intent

allowed:

string

Default:

observation

Observation ID(s) to operate on

allowed:

string

Default:

interpolation

interpolation method in the case of time variable calibrator

allowed:

string

Default:

nearest

Returns
record

Example

 
 
im.setjy(fieldid=2, spwid=-1, fluxdensity=[2.6,0.2,0.3,0.5],standard=’Baars’)  
 
 
Compute the model visibility for field id. 2 to the specified  
point-source (I,Q,U,V) for all spectral windows id.’s on the  
Baars flux density scale.  

__________________________________________________________________


More information about CASA may be found at the CASA web page

Copyright 2016 Associated Universities Inc., Washington, D.C.

This code is available under the terms of the GNU General Public Lincense


Home | Contact Us | Directories | Site Map | Help | Privacy Policy | Search