Calibrating a Mosaicked Spectral Line Dataset

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This page assumes you have converted your data from native MIRIAD format to a CASA measurement set (MS). It also assumes that you have put the filename of the original MS into a global CASA variable, e.g., 

# In CASA
project='c0xxx'
msfile=project+'.ms'


Examining your data

You'll need some information about the IDs that CASA assigns to your calibrators, sources, and antennas. So if you haven't yet done so, 

# In CASA
listobs(vis=msfile)

You will want to know:

  • The FieldId of each of your sources and calibrators.
  • The SpwId of each spectral window you want to calibrate.
  • The Name (or station, but not the ID ) of your reference antenna.

The beginning of the output from listobs.

In this case, the flux calibrator (NEPTUNE) is assigned FldId=0, the bandpass calibrator (3C454.3) is assigned FldId=1, the phase calibrator (2038+513) is assigned FldId=2, and the mosaicked source fields are assigned FldId 3 through 51 (that's field='3~51' in python).

The end of the output from listobs.

In this case, the narrowband windows are assigned to SpwID of 1 and 2, and you can see that they each have 63 channels.

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