2.4.1.0 simulator.setvp

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simulator.setvp - Function

2.4.1 Set the voltage pattern model for subsequent processing

Description

Set the voltage pattern model (and hence, the primary beam) used for a Telecope. There are currently two ways to set the voltage pattern: by using the extensive list of defaults which the system knows about, or by creating a voltage pattern description with the vpmanager. If you are simulating a telescope which doesn’t yet exist, you will need to supply a model voltage pattern using the vpmanager.

sm.predict behavior depends critically on the parameters here, and the ftmachine parameter set in sm.setoptions

sm.predict will always query the vpmanager for a primary beam/VP pattern. if usedefaultvp==True, it will reset the vpmanager first, so that the PB obtained will be the default for the given telescope name if usedefaultvp==False, it will check whether vptable is set, and if so, load that table into the vpmanager and use the beams therein. if usedefaultvp==False and vptable is not set, it will use whatever is already set in the vpmanager (see example below for overriding a default telescope beam).

What sm.predict does with the obtained PB depends on the ftmachine and dovp parameters:

if ftmachine==”mosaic”: - a message ”Performing Mosaic Gridding” indicates that one is using uv domain convolution for simulating from images. - if the primary beam returned by the vpmanager is ALMA, ACA, or OVRO, heterogeneous gridding will be invoked, and the dish diameter set in sm.setconfig, or already in the antenna subtable, will be used to convolve sky model images. for ALMA or ACA, dish diameter =12m will use a 10.7m Airy pattern, and dish diameter =7m will use a 6.25m Airy pattern. see help sm.setoptions for an example. - otherwise the PB returned by the vpmanager will be used. * heterogeneous simulation only works at present from a sky model image, NOT from sky model components. If you want to simulate a heterogeneous array, please add components to an image using ia.modify, and don’t specify a component list in sm.predict. Homogeneous array simulation from component lists works fine. - IF dovp=True, the primary beam returned by the vpmanager will be used to convolve sky model components. This is not automatically invoked by ftmachine=”mosaic”, but needs to be set explicitly with sm.setvp() if you are simulating from components in addition to or instead of sky model images.

if ftmachine==”ft” (the default): - a message ”Synthesis Gridding” indicates that if requested with dovp==True, image domain PB convolution will be used. - if dovp==True, the primary beam returned by the vpmanager will be used to convolve sky model components and images.

Arguments


Inputs
dovp	Multiply by the voltage pattern (ie, primary beam) when simulating
	allowed:	bool
	Default:	true
usedefaultvp	Look up the default VP for this telescope and frequency?
	allowed:	bool
	Default:	true
vptable	If usedefaultvp is false, provide a VP Table made with vpmanager
	allowed:	string
	Default:	Table
dosquint	Activate the beam squint in the VP model
	allowed:	bool
	Default:	true
parangleinc	Parallactice angle increment for squint application
	allowed:	any
	Default:	variant 360deg
skyposthreshold	Position threshold on the sky for feed arrays ??
	allowed:	any
	Default:	variant 180deg
pblimit	Primary beam limit to use in feed arrays ?
	allowed:	double
	Default:	1.0e-2

Returns
bool

Example

    # use the default primary beam in subsequent sm.predict (according to
    # whatever telescope name was set in sm.setconfig)
    sm.setvp(dovp=True, usedefaultvp=True)
    sm.predict(imagename="point.ra10.image",complist="point.cl")

    # use an alternate VP table e.g. of the format created by vpmanager:
    sm.setvp(dovp=True, usedefaultvp=False, vptable=’MyAlternateVLAPBModel.TAB’, dosquint=F);
    sm.predict(imagename="point.ra10.image",complist="point.cl")

    # set a VP and then use it overridding the default
    # (if telescope="NGVLA" was used previously in setconfig,
    # or if an MS was loaded with observatory name = "NGVLA")
    vp.setpbairy(telescope="NGVLA",dishdiam="10m",maxrad="5deg")
    sm.setvp(dovp=True,usedefaultvp=False)
    sm.predict(imagename="point.ra10.image",complist="point.cl")

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