Polarization Calibration

CASA Modification Request 14C108, November 2007



1. Introduction

A polarization calibration task is needed in casa. Most of the software pieces already exist in the aips++ package.

2. Background

One of the strengths of the casa/aips++ package is its clean concept of dealing with all Stokes parameters. However, the necessary software to utilize the polarization capabilities in a task is not yet available.

3. Requirements

Casa should have a polarization calibration task relatively soon. It is a basic requirement of EVLA and to a lesser extent, ALMA data. For very high dynamic range images, accurate polarization calibration is necessary.

4. Design

Most of the design of the polarization calibration is already present in the tool kit and aips++ kit. There are two parts to the calibration: Determining the leakage terms (the D terms) and determining the phase difference between the two total polarizations. Developing a task which could do both of these calibrations at once would be more convenient than the software in AIPS.

5. Deployment Checklist

6. Test Plan

6.1 Internal Testing

6.2 Sponsor Testing

The comparison of the casa task results with several data sets that have been processed in AIPS is the best method for testing and validating the casa software.

6.3 Integration/Regression Tests

A regression test specifically designed for accurate polarization imaging should definitely be available and used routinely.

6.4 Testing for Scientific Validity

See 6.2 for the first stage of validation. Later stages of validation will involve very high dynamic range images to determine if the second order terms of the polarization calibration are sound.


Signatures

APPROVED: I acknowledge that my request is fully contained in this MR, and if the CASA development group delivers exactly what I specified, I will be happy.

ACCEPTED: I acknowledge that I have validated the completed code according to the acceptance tests, and I am happy with the results.

Written - - - - -
Checked - - - - -
Approved by Scientific Sponsor - - - - -
Accepted/Delivered by Sponsor - - - - -

Symbols:
  • Use %X% if MR is not complete (will display ALERT!)
  • Use %Y% if MR iscomplete (will display DONE)


Discussion Area

-- NicoleRadziwill - 30 Oct 2007

-- EdFomalont - 06 Nov 2007
Topic revision: r3 - 2007-11-06, EdFomalont
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