National Radio
Astronomy Observatory

1.6.3.1 Prior Calibration

The setjy task calculates absolute fluxes for measurement set base on known calibrator sources. This can then be used in later calibration tasks. Currently, setjy knows the flux density as a function of frequency for several standard EVLA flux calibrators and solar system objects, and the value of the flux density can be manually inserted for any other source. If the source is not well-modeled as a point source, then a model image of that source structure can be used (with the total flux density scaled by the values given or calculated above for the flux density). Models are provided for the standard VLA calibrators.

Antenna gain-elevation curves (e.g. for the EVLA antennas) and atmospheric optical depth corrections (applied as an elevation-dependent function) may be pre-applied before solving for the bandpass and gains. This is currently done by setting the gaincurve and opacity parameters in the various calibration solving tasks.

There is now a gencal task to create calibration tables for known delay and antenna position offsets.

See § 4.3 for more details.

More information about CASA may be found at the CASA web page

Copyright © 2010 Associated Universities Inc., Washington, D.C.

This code is available under the terms of the GNU General Public Lincense