Baseband Stitching

Overview

In order to maintain constant rms noise across an observed frequency range, one may "overlap" EVLA basebands, offsetting one by 0.5 times the subband width. This way, the decreased sensitivity at subband edges can be edited out, and these frequency ranges replaced with data from the other baseband.

The contributed task stitch can be used to make this process simpler. Given a basic set of inputs, it will select channel ranges for each spectral window, which can then be used to run {split} to create a new measurement set (MS) (stitch can also run {split}, further simplifying things).

Here, we demonstrate the use of the stitch task. For information on reducing the data after running stitch, see the other CASA Guides EVLA tutorials — the data can be treated in the standard way.

Obtaining and installing stitch

First, you will need to download two files that are needed to build the task:

File:Task stitch.py File:Stitch.xml

Because of a quirk in the way Wiki stores files, you need to rename these to no longer have capitalized first letters, task_stitch.py and stitch.xml. Next, run buildmytasks to build the needed files for the task. This can either be done in CASA, or in a UNIX shell. You must be inside the directory where you have saved the files.

# In CASA
!buildmytasks

or:

# In the shell
buildmytasks