katsdpimager.sky_model module¶
Load a local sky model from file and transfer it to a model image
At present the only file format supported is a katpoint catalogue file, but other formats (e.g. Tigger) may be added later.
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class
katsdpimager.sky_model.KatpointSkyModel(catalogue)¶ Bases:
katsdpimager.sky_model.SkyModelSky model created from a
katpoint.Catalogue.-
flux_density(wavelength)¶ Get flux densities for the sources at the given wavelength/frequency.
- Parameters
wavelength (Quantity) – Wavelength or frequency
- Returns
Flux densities in Jy, shape N×4 for Stokes IQUV
- Return type
array
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lmn(phase_centre)¶ Get direction cosine coordinates of the sources
- Parameters
phase_centre (Quantity) – RA and DEC of phase centre
- Returns
The l/m/n coordinates, shape N×3
- Return type
array
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exception
katsdpimager.sky_model.NoSkyModelError¶ Bases:
ExceptionAttempted to load a sky model for continuum subtraction but there isn’t one
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class
katsdpimager.sky_model.SkyModel¶ Bases:
objectA sky model which can be used to generate images at specified frequencies.
This is an abstract base class.
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flux_density(wavelength)¶ Get flux densities for the sources at the given wavelength/frequency.
- Parameters
wavelength (Quantity) – Wavelength or frequency
- Returns
Flux densities in Jy, shape N×4 for Stokes IQUV
- Return type
array
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lmn(phase_centre)¶ Get direction cosine coordinates of the sources
- Parameters
phase_centre (Quantity) – RA and DEC of phase centre
- Returns
The l/m/n coordinates, shape N×3
- Return type
array
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katsdpimager.sky_model.catalogue_from_telstate(telstate, capture_block_id, continuum, target)¶ Extract a katpoint catalogue written by katsdpcontim.
- Parameters
telstate (
katsdptelstate.TelescopeStateorkatdal.sensordata.TelstateToStr) – Telescope statecapture_block_id (str) – Capture block ID
continuum (str or
None) – Name of the continuum imaging stream (used to form the telstate view). IfNone, there must be exactly one continuum imaging stream in the data set, which is used.target (
katpoint.Target) – Target field
- Raises
NoSkyModelError – If no sky model could be found for the given parameters
- Returns
- Return type
katpoint.Catalogue
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katsdpimager.sky_model.open_sky_model(url)¶ Load a sky model from an external resource.
The format is encoded in the URL as a format query parameter, and defaults to
katpoint.- Parameters
url (str) –
The interpretation depends on the format.
- katpoint
A
file://URL for a katpoint catalogue file- katdal
A katdal MVFv4 URL. The following extra query parameters are interpreted and removed before they are passed to katdal:
- target (required)
Description of the katpoint target whose LSM should be loaded
- continuum (optional)
Name of the continuum image stream. If not specified, there must be exactly one in the file.
- Raises
ValueError – if format was not recognised, the URL doesn’t contain the expected query parameters, or the URL scheme is not supported
IOError, OSError – if there was a low-level error reading a file
Exception – any exception raised by katdal in opening the file
- Returns
- Return type