Recommendations for amplitude calibration for early Ka-band observing

We do not yet have good models of our standard amplitude calibrators at Ka-band. However, we have carried out tests of whether the existing K and/or Q-band models can be used for Ka-band amplitude calibration, if scaled appropriately*. Models for all the primary flux calibrators (3C138, 3C147, 3C286 and 3C48) exist in both the AIPS and CASA data reduction packages for all the standard VLA (not EVLA) frequencies. Based on test results for 3C147 and 3C286 obtained in the B-configuration with 6 Ka-band receivers we recommend:

1. observers should attempt to use 3C286 whenever possible because it is almost unresolved and both the K and Q-band models work very well.
2. for other calibrators (based on the 3C147 test) observers should use either the K or Q band flux calibrator models when reducing their data, which seem to work similarly and sufficiently well.

*Note that in both AIPS and CASA the flux density of the amplitude calibrator is first set by the user. When the amplitude calibration is carried out with a model, the model flux density is scaled to that set by the user. The K/Q-band models can therefore be used directly without any adjustment to the Ka-band flux density.

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