National Radio
Astronomy Observatory

3.3.1.1 Loading and Selecting Data

When plotms is first started, a window will appear as in Figure 3.1. It will, by default, display the Plots tab (as chosen from the tabs at the top of the plotms window—e.g., Plots, Flagging, Tools...) and the Plots > Data tab (as chosen from the tabs on the far left side of the plotms window—e.g., Data, Axes, Trans, Iter...). First, a measurement set should be loaded by clicking on Browse near the top of the Plots > Data tab, and selecting a .ms directory (just select the directory itself; do not descend into the .ms directory). A plot can now be made of the measurement set by clicking on Plot—but beware, this would plot the entire measurement set, and could take quite some time! It is probably better to select a subset of the measurement set using the Selection windows in the Plots > Data tab before clicking Plot.

The options for data selection are:

• field
• spw
• timerange
• uvrange
• antenna
• scan
• corr
• array
• msselect

These are described in § 2.3. Note that, unlike when setting data selection parameters from the CASA command line, no quotation marks are needed around strings.

When a plotting parameter has been changed, it will turn red (for example, when a new measurement set is loaded, File Location turns red). This alerts the user that, if the Plot button is clicked, a change will be made to the displayed plot.

Once you have selected the desired subset of data, if you click Plot, plotms will by default plot amplitude versus time. See the next section for information about other possible axes.

For a given data selection, plotms will only load the data once. This speeds up plotting considerably when changing plot parameters such as different axes, colors etc. Sometimes, however, the data changes on disk, e.g., when other data processing tasks were applied. To force plotms to reload the data, checkmark the little force reload box left to the Plot’ button or press the SHIFT key while clicking the Plot button.

More information about CASA may be found at the CASA web page

Copyright © 2010 Associated Universities Inc., Washington, D.C.

This code is available under the terms of the GNU General Public Lincense