National Radio
Astronomy Observatory

1.6.3.2 Bandpass Calibration

The bandpass task calculates a bandpass calibration solution: that is, it solves for gain variations in frequency as well as in time. Since the bandpass (relative gain as a function of frequency) generally varies much more slowly than the changes in overall (mean) gain solved for by gaincal, one generally uses a long time scale when solving for the bandpass. The default ’B’ solution mode solves for the gains in frequency slots consisting of channels or averages of channels.

A polynomial fit for the solution (solution type ’BPOLY’) may be carried out instead of the default frequency-slot based ’B’ solutions. This single solution will span (combine) multiple spectral windows.

Bandpass calibration is discussed in detail in § 4.4.2.

If the gains of the system are changing over the time that the bandpass calibrator is observed, then you may need to do an initial gain calibration (see next step).

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