The MIRIAD task uvgen can be used to simulate a variety of observing modes. Additionally it can simulate the a number of systematic and random errors and non-ideal effects that a synthesis instrument will typically suffer.
Simulating a telescope approximately, let alone in some detail, requires a good many parameters. uvgen takes an appreciable number of parameters and input files to describe the telescope, correlator and source. Fortunately keyword and set-up files for some common situations exist ( e.g. simulating the ATCA and VLA). Also the defaults are usually sensible.
Some inputs to uvgen , and typical values for the ATCA, are given below. Note that these are not the default values.
These typical values for the ATCA (and also the VLA) can be found in
in `keyword' files, found in the $MIRCAT directory.
The parameters in these files can be loaded from within the miriad
shell using the source command.
For example, to load typical parameters for the ATCA, use
miriad% source $MIRCAT/uvgen.def.at
By leaving some of uvgen 's parameters unset ( e.g. leakage, systemp, pbfwhm) you get an idealised telescope (no polarisation leakage, no receiver noise, no primary beam effects). Nor is there any reason that you cannot request an ATCA-like telescope to produce Stokes I or circular polarisations!
The source, antenna and correlator description files are described in the
help for uvgen
, as are a number of other parameters needed in the
simulation process. There are, however, a collection of description
files for common situations. These are all kept in the $MIRCAT
directory.
Given the various standard keyword and description files kept in the
$MIRCAT directory, it is not particularly difficult to set up the
inputs to uvgen
.
For example, to simulate the `spiral' source using configuration
3.0A, in a continuum mode, you would give the following commands
to the miriad
front-end:
miriad% source $MIRCAT/uvgen.def.at
miriad% source = $MIRCAT/spiral.source
miriad% ant = $MIRCAT/3.0a.ant
miriad% corr = $MIRCAT/at.corr.1
miriad% inp uvgen
and then set or unset other parameters as desired.