.. _Predict.json#/: Predict ======= Simulate visibilities for a given sky model. .. _Predict.json#/inputs: inputs ****** .. _Predict.json#/inputs/type: type ++++ :type: ``string`` :doc: Case-insensitive step type; must be 'predict'. .. _Predict.json#/inputs/applycal.*: applycal.* ++++++++++++++ :doc: Set of options for applycal to apply to this predict. For this applycal-substep, .invert is off by default, so the predicted visibilities will be corrupted with the parmdb. .. _Predict.json#/inputs/beam_interval: beam_interval +++++++++++++ :type: ``double`` :default: ``0`` :doc: Time in seconds between beam evaluations. A value of 0 causes a beam evaluation every timestep, whereas a value of 120 would start by evaluating the beam 60 seconds ahead in time, and reuse this beam for all the next timesteps until the timestep that is 120 seconds removed from the start. Because beam evaluation is relatively expensive, this speeds up processing. A value of 120 seems a good value that improves speed considerably, without affecting accuracy. .. _Predict.json#/inputs/beammode: beammode ++++++++ :type: ``enum`` :doc: Same as in `ApplyBeam `__ step. :symbols: ``array_factor``, ``element``, ``default`` .. _Predict.json#/inputs/beamproximitylimit: beamproximitylimit ++++++++++++++++++ :type: ``float`` :doc: Same as in `ApplyBeam `__ step. .. _Predict.json#/inputs/coefficients_path: coefficients_path +++++++++++++++++ :type: ``string`` :default: ``""`` :doc: For beam models that require a coefficients file (like that MWA), this field should point to that filename. .. _Predict.json#/inputs/correctfreqsmearing: correctfreqsmearing +++++++++++++++++++ :type: ``boolean`` :default: ``False`` :doc: Simulate frequency smearing based on the channel width, by multiplying the visibility with a sinc function. .. _Predict.json#/inputs/correcttimesmearing: correcttimesmearing +++++++++++++++++++ :type: ``boolean`` :default: ``False`` :doc: Simulate time smearing based on the integration time, by multiplying the visibility with a sinc function. This is an approximation. The change of u,v,w due to earth rotation over the integration interval is approximated by a straight line. The axis of rotation is the J2000 pole, so precession is ignored. .. _Predict.json#/inputs/elementmodel: elementmodel ++++++++++++ :type: ``enum`` :default: ``default`` :doc: Specifies which beam model to use. The default value of "default" means that the model is inferred from the MS. For a LOFAR MS the default is hamaker, and for an OSKAR MS the default is oskardipole. :symbols: ``hamaker``, ``lobes``, ``oskarsphericalwave``, ``oskardipole (or any other model EveryBeam supports)`` .. _Predict.json#/inputs/onebeamperpatch: onebeamperpatch +++++++++++++++ :type: ``boolean`` :doc: Same as in `ApplyBeam `__ step. .. _Predict.json#/inputs/operation: operation +++++++++ :type: ``string`` :default: ``replace`` :doc: Should the predicted visibilities be output as is (``replace``, default), should they be subtracted from the input visibilities (``subtract``) or added to them (``add``). .. _Predict.json#/inputs/outputmodelname: outputmodelname +++++++++++++++ :type: ``string`` :default: ``""`` :doc: Name for writing the predicted visibilities in the output DPBuffer. If empty (default), write the output in the main/default visibility buffer, thereby replacing the input visibilities. Otherwise, write the output to an extra (model) data buffer in the output DPBuffer with the given name. .. _Predict.json#/inputs/parallelbaselines: parallelbaselines +++++++++++++++++ :type: ``boolean`` :default: ``False`` :doc: Parallelize sky model prediction over baselines instead of sources. Will speed up performance in certain cases. .. _Predict.json#/inputs/sourcedb: sourcedb ++++++++ :type: ``string`` :doc: Path of sourcedb in which a sky model is stored (the output of makesourcedb). When the path ends with ``.skymodel`` or ``.txt`` DP3 expects a skymodel file as used by makesourcedb. This makes it possible to directly use a skymodel file without using makesourcedb to convert the file. The sourcedb format is described at https://www.astron.nl/lofarwiki/doku.php?id=public:user_software:documentation:makesourcedb . In DP3 v5.3 a change was introduced to fix the projection of Gaussian sources. For backward compatibility, also the old behavior is still supported, using the key ``OrientationIsAbsolute`` in the sky model. To make sure you use the new (and most correct) behavior, add ``OrientationIsAbsolute=true`` to your sky models. .. _Predict.json#/inputs/sources: sources +++++++ :type: ``array`` :default: ``[]`` :doc: Patches to use in the predict step of the calibration. .. _Predict.json#/inputs/usebeammodel: usebeammodel ++++++++++++ :type: ``bool`` :default: ``False`` :doc: Use the beam model in the predict part of the calibration. .. _Predict.json#/inputs/usechannelfreq: usechannelfreq ++++++++++++++ :type: ``boolean`` :doc: Same as in `ApplyBeam `__ step. .. _Predict.json#/inputs/usefastpredict: usefastpredict ++++++++++++++ :type: ``boolean`` :default: ``depends on CMake configuration`` :doc: Make use of the accelerated `predict library `__. This is an **experimental** drop-in replacement for the current implementation in DP3, please use at your own risk! Note that the option is only available when compiling with ``USE_FAST_PREDICT=ON``. If the aforementioned CMake option is enabled, the default value is set to ``true``.