MRK 6: red-shifted HI absorption 5.5.0: Difference between revisions
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This tutorial broadly follows the techniques described in the [[Calibrating a VLA 5 GHz continuum survey|continuum survey tutorial]] and the [[NGC 5921: red-shifted HI emission|21 cm emission tutorial]], and the basic calibration steps are presented only in outline. | This tutorial broadly follows the techniques described in the [[Calibrating a VLA 5 GHz continuum survey|continuum survey tutorial]] and the [[NGC 5921: red-shifted HI emission|21 cm emission tutorial]], and the basic calibration steps are presented only in outline. | ||
== Loading the Data == | |||
Recall that the python file globber [http://docs.python.org/library/glob.html glob] is your friend here! | |||
<source lang="python"> | |||
from glob import glob | |||
fileList = glob("AB658*.xp?") | |||
#importvla(archivefiles=fileList, vis="ab658.ms") | |||
vis = "ab658.ms" | |||
mode = "summary" | |||
vishead | |||
</source> | |||
Revision as of 20:20, 2 February 2010
Overview
This example demonstrates a trickier spectral line data set. In this case, several radio bright active galaxies were observed to look for redshifted 21 cm absorption. The data were obtained using 4IF mode, which means that the full range of velocities were split into two spectral windows. Producing the data cube will require eventually stitching these windows back together.
Download your data from the VLA Archive; in this example we'll use the publicly available survey AB658. These data were published in Gallimore et al. (1999).
With the present archive defaults, you should have obtained the following VLA archive files.
'AB658_A921122.xp1' 'AB658_A921122.xp2' 'AB658_A921122.xp3' 'AB658_A921122.xp4'
This tutorial broadly follows the techniques described in the continuum survey tutorial and the 21 cm emission tutorial, and the basic calibration steps are presented only in outline.
Loading the Data
Recall that the python file globber glob is your friend here!
from glob import glob
fileList = glob("AB658*.xp?")
#importvla(archivefiles=fileList, vis="ab658.ms")
vis = "ab658.ms"
mode = "summary"
vishead
