## Optical versus Radio

The types of data files treated by POINT differ slightly. For Optical data, the pointing error is relative to a perfect antenna. Hence the POINTPRINT output directly indicates the new pointing parameter values. For Radio (or Interferometer) data, however, the pointing error is relative to the previous model, except for the collimations. Hence POINTPRINT yields directly COH and COV, but for all other parameters the POINT results should be added to the previous values.

In particular, the Radio results can be used in the OBS SETPOINTING command in an incremental way:

         SET\POINTING IAZ IAZ+dIaz IEL IEL+dIel/ANTENNA 2

where dIaz, dIel are the results given by command POINTPRINT for the parameters IAZ, IEL.