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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.  

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