Spectral Line Five Points

The operator must use SPA to reduce the five observations and produce a fit. For example, the 5 scans could be simultaneously reduced and put in an S-file (say, S4) using the command sequence
S4 = SCAN # to SCAN # BAS LIN
Then, set the Z variable in the PEAK command to be the LIN parameter you wish to fit (usually YMAX or YINT), and perform the 2-D gaussian fit with the command
S4 PEAK
which also prints results of the fit.

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Table 4.7

FIVE Keywords

TMAIN (seconds)

Total integration time (seconds) for on-source observation.

TREF (seconds)

Total integration time (seconds) for off-source observation.

RPT (integer)

Set number of ON/OFF sequences at each of the 5 mapping points.

HP (decimal degrees)

Set the grid spacing between points in the map (see Figures 4.6 and 4.7) (in degrees). This is usually one-half of the beamwidth at the working frequency.

KMAP (1 or 2)

Do an AZ/EL (1) or RA/DEC (2) five point map.

OFFS 0 or 1

Set each of five points to have a single (0) or separate (1) reference point.

NSCAN (integer)

Set the number of five point maps to be done consecutively using the above parameters.

TSAMPLE (seconds)

For CONT mode only. The integration time for each data point recorded by the computer.

FITBW (0 or 1 or 2)

For CONT mode only. This parameter sets the mode for the least squares two-dimensional gaussian fitting that takes place after the five point map is complete.

0

means to not do any fitting of the data.

1

means to fix the beamwidths at 2 times the value typed in for HP and then to only fit for the gaussian amplitude and offsets.

2

means to fit for both beamwidths and offsets.

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