In spectral line or continuum mode the five point mapping program, FIVE , takes data at five positions centered on the MAIN coordinate position and spaced by HP (degrees). At each five point position the telescope is position switched using either the same reference position (if keyword OFFS is set to 0, see Figure 4.6) or 5 separate reference positions (if OFFS is set to 1, see Figure 4.7). Five point maps can be made in either the AZ , EL or RA , DEC coordinate systems. This is determined by setting the keyword KMAP to 1 for AZ , EL or to 2 for RA , DEC .
In continuum mode the five point fit can be performed automatically using the keyword FITBW, or can be computed manually using SPA. In spectral line mode the only choice is for the observer to compute the fit parameters using SPA. It is possible to use data from more than one five point map to compute a fit by putting scans from different five points in a single S-file, and, then using the SPA commands as outlined in the next section.
