4 An overview of the reduction

 4.1 Pointing observations
 4.2 Focus observations
 4.3 Flux calibrator observations
 4.4 Line source science observations
 4.5 Continuum source science observations

The data reduction for ACSIS depends on the type of data being reduced. Calibration observations (pointings, focus, and flux calibrators) are reduced differently from science observations. Further, science observations are reduced differently based on what type of science is being done; planetary continuum observations have different processing steps from line sources.

4.1 Pointing observations

Pointing observations are used to ensure that the telescope is pointing in the correct location.

In reducing pointing observations, two different methods are done. The first assumes that a continuum source has been observed, and the second assumes that a line source has been observed.

In both modes, the time-series data are first regridded to form a cube. In continuum mode, the spectral regions lacking lines are collapsed to form an image, and in line mode the line regions are collapsed to form an image. If a five-position pointing is done, then a Gaussian is fit to horizontal and vertical cuts (which correspond to azimuth and elevation) to determine the location of the pointing source. Otherwise, centroiding is done on the source. The calculated pointing offset is then reported to the user.

4.2 Focus observations

Focus observations are used to ensure that the telescope is focussed.

Orac-dr currently does not calculate any focus measurements. The time-series data are only regridded to form a cube.

4.3 Flux calibrator observations

4.4 Line source science observations

4.5 Continuum source science observations