<casaxml xsi:schemaLocation="http://casa.nrao.edu/schema/casa.xsd file:///opt/casa/code/xmlcasa/xml/casa.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://casa.nrao.edu/schema/psetTypes.html">
<task category="simulation" name="simalma" type="function">
<needs>simanalyze</needs>
<needs>simobserve</needs>
<shortdescription>Simulation task for ALMA </shortdescription>
This task simulates ALMA observation including 12-m, ACA 7-m and total
power arrays, and images and analyzes simulated data.
This task makes multiple calls to simobserve (to calculate
visibilities and total power spectra), followed by gridding of total
power spectra (if total power is requested), concatenation of the
simulated visibilities, calls to the simanalyze task for visibility
inversion and deconvolution and calculation of difference and fidelity
images, and feathering of single dish and interferometric data.
These steps may not all be familiar to new users, so the simalma task
runs by default in a "dryrun" mode, in which it assesses the user's
input parameters and sky model, and prints an informational report
including the required calls to other CASA tasks, both to the screen
and to a text file in the project directory (defined below).
The user can modify their parameters based on the information, then
either run with dryrun=False to actually call the other tasks to
create the simulated data, or run the other tasks individually one at
a time to better understand and control the process.
NOTE The ALMA project is refining the optimal method of combining the
three types of data. If that best practice is changed after this
release of CASA, the user can control the process by modifying the
calls to the other CASA tasks.
-------------------------------
project -- root filename for all output files. A subdirectory will be
created, and all created files will be placed in that subdirectory
including the informational report.
-------------------------------
skymodel -- input image (used as a model of the sky)
* simalma requires a CASA or fits image. If you merely have a grid of
numbers, you will need to write them out as fits or write a
CASA script to read them in and use the ia tool to create an image
* simalma does NOT require a coordinate system in the header. If the
coordinate information is incomplete, missing, or you would like to
override it, set the appropriate "in" parameters. NOTE that setting
those parameters simply changes the header values, ignoring
any values already in the image. No regridding is performed.
* If you have a proper Coordinate System, simalma will do its best to
generate visibilities from that, and then create a synthesis image
according to the specified user parameters.
* You can manipulate an image header manually with the "imhead" task.
inbright -- peak brightness to scale the image to in Jy/pixel,
or "" for unchanged
* NOTE: "unchanged" will take the numerical values in your image
and assume they are in Jy/pixel, even if it says some other unit
indirection -- central direction to place the sky model image,
or "" to use whatever is in the image already
incell -- spatial pixel size to scale the skymodel image,
or "" to use whatever is in the image already.
incenter -- frequency to use for the center channel (or only channel,
if the skymodel is 2D) e.g. "89GHz",
or "" to use what is in the header.
inwidth -- width of channels to use, or "" to use what is in the image
should be a string representing a quantity with units e.g. "10MHz"
* NOTE: only works reliably with frequencies, not velocities
* NOTE: it is not possible to change the number of spectral planes
of the sky model, only to relabel them with different frequencies
That kind of regridding can be accomplished with the CASA toolkit.
-------------------------------
complist -- component list model of the sky, added to or instead of skymodel
see http://casaguides.nrao.edu/index.php?title=Simulation_Guide_Component_Lists_%28CASA_4.1%29
compwidth -- bandwidth of components; if simulating from components only,
this defines the bandwidth of the MS and output images