Predict

Simulate visibilities for a given sky model.

inputs

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.

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.

type:: boolean
default:: False
doc:: Simulate frequency smearing based on the channel width, by multiplying the visibility with a sinc function.

type:: int
default:: 1
doc:: Apply time smearing correction by upsampling the uvw values before predicting and averaging the predicted data afterwards. The value is the upsampling and averaging factor. A value of 0 or 1 disables time smearing.

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)

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).

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.

type:: boolean
default:: False
doc:: Parallelize sky model prediction over baselines instead of sources. Will speed up performance in certain cases.

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.