Example

There are two ways to generate and apply double-circle gaintable. One is to calibrate and apply atmosphere and sky calibrations separately, and the other is to apply them on-the-fly during double-circle gain calibration. The latter should be more efficient. Examples for these two procedures are shown below.

Apply atmosphere and sky caltables separately

To compute a gaintable and subsequently apply it using applycal:

  1. Generate the $T_{sky}$ and $T_{sys}$ calibration tables, and apply them (sdcal)
  2. Split out the corrected column data (split)
  3. Generate the double-circle gaincal calibration tables (sdgaincal)
  4. Apply the double-circle gaincal calibration tables (applycal)

In CASA, this looks like the following:

sdcal(infile=inputvis, calmode='ps,tsys,apply')
split(vis=inputvis, outputvis=calibratedvis, datacolumn='corrected')
sdgaincal(infile=calibratedvis, outfile='DCgaintable', calmode='doublecircle')
applycal(vis=calibratedvis, gaintable='DCgaintable')

Apply atmosphere and sky caltables on-the-fly

To compute a gaintable and subsequently apply it using applycal:

  1. Generate the $T_{sky}$ and $T_{sys}$ calibration tables (sdcal)
  2. Generate the double-circle gaincal calibration tables by applying $T_{sky}$ and $T_{sys}$ calibration tables on-the-fly (sdgaincal)
    • You can set spwmap and interp for each pre-application caltable if necessary
  3. Apply the double-circle gaincal calibration tables (applycal)

In CASA, this looks like the following:

sdcal(infile=inputvis, calmode='ps', outfile='sky.tbl')
sdcal(infile=inputvis, calmode='tsys', outfile='tsys.tbl')
sdgaincal(infile=inputvis, applytable=['sky.tbl', 'tsys.tbl'], outfile='DCgaintable', calmode='doublecircle')
applycal(vis=inputvis, gaintable='DCgaintable')