Transfering the solution to other uv data sets.

An important use of the Self-calibration is to compute a calibration solution using wide bandwidth data (continuum data, where signal-to-noise can often be maximized) and apply it to high spectra resolution (line) data.

The technique is quite simple. Solve for Self-calibration using the wide bandwidth data as usual, and save the results (gain tables) using the WRITE CGAINS command (eventually one for each of the PHASE or AMPLI steps of Self-calibration).

At any time, you can read back these gain tables using READ CGAINS, read an uv data set with READ UV and apply the gain solution using command APPLY. Since Self-calibration normally corrects for atmospheric errors, the derived “phase” correction is in general here to compensate for a pathlength change, i.e. the corresponding phase correction should scale as Frequency. APPLY DELAY instructs IMAGER to take this effect into account.

A simpler approach (based on these elemental steps) is to use the PIPELINE to compute and apply Self-Calibration consistently over a complex data set with different spectral windows.