Continuum polarimetry case

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Continuum polarimetry case

To start msplot from the Glish command line interface type:

include 'msplot.g'
plot := msplot(msfile='ap366.ms',
            edit=T);                # Allow editing as well as inspection

The msplot control GUI will come up (Fig. 1.5). Left-click on the Data selection button to get data selection criteria. Type a field number in the FIELD_ID input to see a particular source. Then, in the top left corner of the msplot control GUI, select ``Plot X vs Y'' - the default is to plot uv distance vs. observed amplitude. To plot something different, click on the X axis or Y axis buttons to select and scroll your cursor to the option you want. Once you have selected the subset of the data you want to plot and how you want to plot it, left-click on Go (upper right on the msplot interface) to create the plot. In the plot window (right panel of Fig. 1.5), you can use the cursor to select regions and then left-click on the Locate button to identify baselines associated with each uv point. Left-lick on the Flag or Unflag buttons on the plot to flag/unflag selected data.

**Figure 1.5:** Visualizing your data. **Left:** The `msplot` control GUI. Left-click on the **Data selection** button and fill in the FIELD_ID blank (here source number 11, 1328+307, is chosen). **Right:** A plot of uv distance vs. observed amplitude created when you left-click on the Go button in the `msplot` control GUI. RR and LL polarizations have an amplitude of about 0.75 Jy while RL and LR are near 0.1 Jy.
$\begin{figure}\epsfig{file=cookbook.dir/vla.msplot.control.ps, height=2.in} \epsfig{file=cookbook.dir/vla.msplot.xyplot.ps, height=2.in}\hrulefill \end{figure}$

While you are in the msplot function, you can get a plot of antenna locations in the array. To do this, Left-click on the Data selection button. To the right of the ANTENNA selection space is a ``wrench'' icon, left-click on the wrench and choose the FROM MS option. A plot of antenna locations (Fig. 1.6) will pop up in a separate window. You can use this plot to select antennas in the array to plot (e.g. use your left-mouse button to draw one or more boxes around antennas to select them, then click on the Accept button to write those antenna names to the msplot data selection window for plotting). You can print this plot to hardcopy by left-clicking on the File button and choosing the print option. This plot is useful to choose a well-behaved antenna near the center of the array for your reference antenna. For the continuum polarimetry dataset, Antennas 2, 4, 8, & 9 are all good choices. When you are finished with the plot, left-click on the Dismiss button in the lower right corner of the antenna plot. Note: you can also identify antennas near the center of the array using the ms.summary listing of antenna locations (Appendix 4). For example: Antenna 4, located at Station VLA:W8, is only 8 meters from the array center on the West arm.

When you are finished with the msplot tool, click on the Done button in the lower right corner of the msplot GUI.

**Figure 1.6:** Antenna plots as a function of position in the array. **Left:** for the continuum polarimetry data. **Right:** for the spectral line data.
$\begin{figure}\centering\leavevmode \epsfxsize =.45\columnwidth \epsfbox{cookb... ...\columnwidth \epsfbox{cookbook.dir/vla.msplot.antS.ps} \hrulefill \end{figure}$

Next: Spectral-line case Up: Data examination and inspection Previous: Data examination and inspection Contents