ALMA SIS14 apcal: Difference between revisions
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== Setup == | == Setup == | ||
To run this tutorial, you need the measurements set "sis14_ampandphase.ms." This measurement set contains only a quasar (the phase calibrator from the parent data set). If you are using the pre-provided directory structure then you want to work in the | To run this tutorial, you need the measurements set "sis14_ampandphase.ms." This measurement set contains only a quasar (the phase calibrator from the parent data set). If you are using the pre-provided directory structure then you want to work in the directory: | ||
<pre style="background-color: #fffacd;"> | <pre style="background-color: #fffacd;"> | ||
| Line 8: | Line 7: | ||
</pre> | </pre> | ||
and you can copy the data to your working directory using the commands | (relative to the root for the package) and you can copy the data to your working directory using the commands | ||
<source lang="python"> | <source lang="python"> | ||
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os.system("cp -r ../../working_data/sis14_ampandphase.ms sis14_ampandphase.ms") | os.system("cp -r ../../working_data/sis14_ampandphase.ms sis14_ampandphase.ms") | ||
</source> | </source> | ||
With this measurement set in place, you can follow the tutorial below inside the "basic_cal/" directory. | |||
== Overview == | == Overview == | ||
Revision as of 18:42, 28 February 2014
Setup
To run this tutorial, you need the measurements set "sis14_ampandphase.ms." This measurement set contains only a quasar (the phase calibrator from the parent data set). If you are using the pre-provided directory structure then you want to work in the directory:
lessons/basic_cal/
(relative to the root for the package) and you can copy the data to your working directory using the commands
# In CASA
os.system("rm -rf sis14_ampandphase.ms")
os.system("cp -r ../../working_data/sis14_ampandphase.ms sis14_ampandphase.ms")
With this measurement set in place, you can follow the tutorial below inside the "basic_cal/" directory.
Overview
Phase Calibration (per Scan)
First, we calibrate phase as a function of time.
# In CASA
listobs("sis14_ampandphase.ms")
Now we calibrate the phase correction for each antenna as a function of time.
# In CASA
os.system("rm -rf phase.cal")
gaincal(vis="sis14_ampandphase.ms",
caltable="phase.cal",
field="0",
solint="inf",
calmode="p",
refant="DV22",
gaintype="G")
Now we plot the results of the calibration.
# In CASA
plotcal(caltable="phase.cal",
xaxis="time",
yaxis="phase",
subplot=331,
iteration="antenna",
plotrange=[0,0,-180,180])
Amplitude Calibration (per Scan)
Now calibrate the amplitude response of each antenna as a function of time.
# In CASA
os.system("rm -rf amp.cal")
gaincal(vis="sis14_ampandphase.ms",
caltable="amp.cal",
field="0",
solint="inf",
calmode="a",
refant="DV22",
gaintype="G",
gaintable="phase.cal")
Plot the results of this fit.
# In CASA
plotcal(caltable="amp.cal",
xaxis="time",
yaxis="amp",
subplot=331,
iteration="antenna",
plotrange=[0,0,0,0])
Phase and Amplitude Calibration (per Integration)
We can also solve for the antenna corrections on shorter timescales.
# In CASA
os.system("rm -rf apcal_int.cal")
gaincal(vis="sis14_ampandphase.ms",
caltable="apcal_int.cal",
field="0",
solint="int",
calmode="ap",
refant="DV22",
gaintype="G")
Plot the per-integration variation of the phase.
# In CASA
plotcal(caltable="apcal_int.cal",
xaxis="time",
yaxis="phase",
subplot=331,
iteration="antenna",
plotrange=[0,0,-180,180])
Now plot the per-integration variation of the amplitude.
# In CASA
plotcal(caltable="apcal_int.cal",
xaxis="time",
yaxis="amp",
subplot=331,
iteration="antenna",
plotrange=[0,0,0,0])
