Calibrate the azimuth tilt meter.

Arguments:

Double af_offset

The zero offset tilt of the aft-fore tilt meter.

Double af_scale

The scale factor of the aft-fore tilt meter.

Double lr_offset

The zero offset tilt of the left-right tilt meter.

Double lr_scale

The scale factor of the left-right tilt meter.

Example:

The following example calibrates the tilt-meter scale factors and offsets that are used in the pointing model. The first two arguments indicate that the aft-fore tilt-meter readings need to be offset by 0.0156 degrees and scaled by 1.093, to make them reflect the true aft-fore tilt of the azimuth platform. Similarly the second two arguments indicate that the left-right tilt meter needs to be offset by 0.1025 degrees and scaled by 0.727 to make it reflect the true left-right tilt of the azimuth platform.

  cal_tilt_meter 0.0156, 1.093, 0.1025, 0.727

Context:

The cal_tilt_meter command specifies the scale factors and offsets that are used by the pointing model, to correct the rough hardware conversion parameters specified by the conf_tilt_meter command. Whereas the hardware conversion parameters are fixed values that come from the manufacturer's documentation of the tilt-meters, the calibration factors established by the cal_tilt_meter command generally come from fitting these pointing model terms to observations of astronomical point sources.

Beware that the af_offset term behaves almost identically to an elevation offset, except that it is applied earlier in the pointing model correction procedure than an elevation offset specified by the cal_az_el command.

Also note that it is difficult to distinguish between a real offset in the left-right tilt meter, and a tilt of the elevation axis out of the plane of the azimuth platform.