Getting Started in CASA

Installing CASA

See the CASA Primer for installation instructions for common OSs.

Installing CASA

CASA is available via the your NRAO portal http://my.nrao.edu. You may need to register if you have not been using NRAO services in the past. CASA is available for MacOS X and Linux platforms and installation instructions are provided at https://safe.nrao.edu/wiki/bin/view/Software/ObtainingCASA

Installing CASA on Ubuntu

The following method worked for Ubuntu 9.04 (Jaunty).

• Download the tarball appropriate for your Linux distribution (from https://svn.cv.nrao.edu/casa/linux_distro/).
  • 32-bit Linux
  • 64-bit Linux
• Install to /usr/local/bin/CASA (or substitute your own directory).

sudo mkdir /usr/local/bin/CASA
sudo mv casapy-30.0.9860-001-64b.tar.gz /usr/local/bin/CASA # this is for 64-bit installation; substitute the appropriate tarball here
cd /usr/local/bin/CASA
sudo tar zxvf casapy-30.0.9860-001-64b.tar.gz

• Add the following environment variable to your .bashrc (or the equivalent command for your preferred shell startup script).

export PATH=$PATH:/usr/local/bin/CASA/casapy-30.0.9860-001-64b

• Test it out!

source ~/.bashrc # or open a new terminal
casapy

Starting CASA

Once installed, you can start CASA using the command "casapy"

## From a UNIX shell prompt
casapy

Note that, by convention, UNIX-level commands will be commented out so to facilitate parsing these pages into CASA scripts.

Listing Available Commands and Tools

# From within CASA
tasklist()

A more exhaustive summary can be obtained as follows.

taskhelp

Some commands are hidden away as methods under various objects. For example, to take a look at options under the imager object

help im

Notice that the method mem appears here, under help, but not under tasklist.

Getting Help on a Command

Let's get some exhaustive help on clean.

# From within CASA
help clean

This method is OK, and perhaps the following method is better.

# From within CASA
pdoc clean

Quitting CASA

You can exit CASA by typing quit,

# From within CASA
exit

or CTRL-D at the casapy prompt. If you don't want to see the question "Do you really want to exit [y]/n?", then just type

# From within CASA
Exit

and CASA will stop right then and there.

Additional Tips

New Startup Screen

• When you started CASA, it gave you a lot of useful information. But now you've been mucking around for a while, and that info is lost. How do you get it back? Just rerun the startup screen.

startup

Setting up the available memory

CASA's default is to use 90% of the memory available. This should be a good setting for most users.

However, if this does not suit your needs, you can set the amount of memory that CASA will use, either in absolute or relative units.

To do so, create a ~/.casarc file in your home directory (if you still have an ~/.aipsrc in your home directory, it would be wise to remove it).

Within ~/.casarc add the following variable:

system.resources.memory: <absolute_number>

or

system.resources.memfrac: <relative_number>

where <absolute_number> stands for the allocated memory in units of MB. e.g. for 16GB of memory the number would be 16000. <relative_number> stands for the percentage of memory that CASA can access, e.g. a value of 80 corresponds to 80% of the memory installed.

Now restart CASA.

Starting CASA without the logger or log messages to terminal

You also have the option of starting CASA without the logger, for example if you are running remotely in a terminal window without an X11 connection, or if you just do not want to see the logger GUI. In this case use the --nologger option:

casapy --nologger

The logger messages will still go into the casapy.log file. If you want to see these at your terminal, use the --log2term option also:

casapy --nologger --log2term

--Jack Gallimore 14:42, 30 October 2009 (UTC)