Band-Specific Guidelines

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The general approach for EVLA data processing will be similar regardless of band, and will consist of (for continuum observations):

  • Flagging of any obvious bad data (flagdata, plotms, viewer)
  • Fixing the flux and spatial distribution of the flux density calibrator (setjy)
  • Performing a bandpass calibration (gaincal for initial phase, bandpass)
  • Performing gain calibration on calibration sources (gaincal)
  • Setting the flux density scale (fluxscale)
  • Transferring the gain calibration to the science target (applycal)
  • Imaging (clean)

A good example of this approach can be found in the EVLA Continuum Tutorial 3C391. Of course, there are many variations on this theme: at some point, the data could be averaged (in frequency and/or time) to reduce its size; this, of course, would depend on the tolerance for bandpass smearing, and ... Furthermore, one may wish to perform Self Calibration if the science target is sufficiently strong.

Low-frequency Bands (L, C)

The greatest concern at low frequencies is radio frequency interference (RFI). A detailed description of this phenomenon, as well as guidelines for how to avoid it (prior to obtaining and observation) and mitigate its effects (if it is present in an observation) can be found on the Radio-Frequency Interference page.