HTT2

↵ Using CASA

= HINTS, TIPS & TRICKS

Getting Started

• What Version of CASA am I Running?
• Starting CASA Without the Logger
• New Startup Screen
• Accessing the Newest Version of CASA at NRAO
• Setting Up the Available Memory
• Capturing Return Values
• Interpreting CASA output

Data Reduction

General

• Renaming a Field
• Renaming Antennas
• Selecting Spectral Windows and Channels
• Axis definitions in plotms
• General description of the data selection syntax
• CASA Region Format
• CASA Region Format Examples How to apply CASA regions to tasks and convert them for use with tools
• Creating lists of files for task input: using glob

Loading Data

• Measurement Set Contents
• Importing Data into CASA
• Loading and Running Tasks
• Averaging data in plotms
• Inspecting Data

Flagging

• Applying EVLA on-line flags What do to if you need to re-apply (or apply) your online flags, without re-downloading the entire MS
• Data flagging with plotms
• Data flagging with viewer

Calibration

• Combining Bandpasses
• Create a Component List for Selfcal
• Creating a Model for a Resolved Bandpass Calibrator

Imaging

• Description of Imaging Algorithms in CASA
• Diverging deconvolution results in 'csclean' and 'mosaic' modes
• Create a Simulated Image
• Create a Clean Mask from Continuum Image or Moment Cube

Analysis

• How to rotate and slice a cube for pV diagrams
• Masking images for analysis
• Stacking Multiple Spectral Lines at Same Position
• Fit an arbitrary sky (image) model to an existing MS - including how to simulate visibilities that will have the same uv-coverage and weights as a given MS
• Fit a Gaussian to Visibility data and plot it over the data

Miscellaneous

Simulations

• Convert jpg to fits
• Antenna Configurations Models in CASA

How CASA Works

• Lattice Expression Language (LEL) as used, e.g. in immath
• Definition of a Measurement Set
• Definition of a Calibration Table
• CASA Parallel Processing

If CASA Doesn't Work

• Interpreting CASA output
• Updating the CASA Data Repository
• Waiting for read-lock on file
• CASA Error Messages
• Fixing out of date TAI_UTC tables (missing information on leap seconds)

Writing a CASA Task

• Writing a CASA Task Presents the basics of writing a CASA task, and provides examples of tasks that will be helpful and instructive.
• User-contributed Tasks

VLA

• Some Notes on VLA / EVLA gain curves and fluxscale
• VLA LST Calculator

Bug Checking

• Check for the CASA Incremental Storage Manager Flagging Bug

Also check out the step-by-step tutorials on this wiki!

↵ CASAguides