Calibration

By selecting the 2-receiver item, a new window interface appears:

 

Figure 3: Interface for dual-frequency calibration

• SELECT selects data file and scans.
• PHCOR computes atmospheric phase correction.
• RF computes the RadioFrequency passband.
• JUMPS identifies possible phase and amplitude discontinuities.
• PHASE computes the phase calibration curve
• EFF. computes the mean telescope efficiencies, and derives flux density of secondary calibrators from the bandpass calibrator.
• AMPL. computes the amplitude calibration curve.
• PRINT prints a text summary (filename.sum) and optionally a PostScript summary with all plots.

Calibration normally proceeds by doing all steps in sequence, from left to right (i.e. SELECT, PHCOR, RF, JUMPS, PHASE, EFF., AMPL.) and then using PRINT to get the summary. Button GO can be used to do it automatically, without any manual intervention. This may be a good starting point.

While steps SELECT, PHCOR, RF, JUMPS, PHASE are in principle straightforward, steps EFF. and AMPL. require proper adjustement of the flux density scale. This is done by the sub-procedure FLUX described in next section. PRINT can be done at any time, although it is only essential for a final summary. PRINT gives a rather detailed report, including phase noise, amplitude stability, estimate of seeing, etc.... However, these results are reset to unknown for each SELECT operation.