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Examples

In this section I describe a few examples of the use of Pieflag. Detailed descriptions have been added to the image captions.

Figure 2 shows the effect of Pieflag on data observed with the ATCA at L-band outside the spectral regions reserved for radio astronomy, between 1.38GHz and 1.48GHz. This band is particularly contaminated by RFI at the beginning and end of observations, when the antennae are pointed towards, or away from, the town of Narrabri, at 20km distance from the telescope.

Figure 3 shows data from the same observing run, but from a different frequency channel. The RFI in this channel has much higher amplitudes, but is confined to very short periods of time. The figure illustrates the effect of the second step of postprocessing.

Figure 4 shows data from an experiment in which the visibility amplitudes are dominated by the astronomical source, which has significant structure. Flagging based on amplitude did not work, since the cutoff was chosen such that much of the RFI at the beginning of the experiment was not detected. However, rms-based flagging did find the affected data. This figure also illustrates that a small amount of RFI in the reference channel has no noticeable effect on the flagging process.

Next: Conclusions Up: Automated Editing of Radio Previous: Limitations