Transfer the flux density scale

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Transfer the flux density scale

For point sources of unknown flux density, but for which valid solutions have been derived against a unit point source model, the absolute flux density can be established by scaling the mean gain amplitudes against those of the known amplitude calibrators. This scaling is achieved using the calibrater.fluxscale function.

In both examples below, the amplitude scale is set with 3C286 as the reference flux density calibrator. The output calibration table contains the scaled G calibration factors for all of the transfer sources, and will be used in subsequent reduction steps. Proper scaling is indicated in the calibrater.plotcal plots by smoothly varying (ideally constant) amplitude gains for each antenna, despite source changes. At high frequencies ( $\nu$ > 15 GHz), this scaling step may be biased by elevation-dependent variation of the atmospheric contribution to the system noise temperature. Methods for treating this case properly will be available in the near future.

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