Other Commands

A few data reduction commands have been modified because of the new functionnality offered by the Time data. Major commands include

• SPECTRUM
  SPECTRUM has disappeared, because the correlator data is already pre-calibrated. There is no longer any raw data.

• COMPRESS
  COMPRESS now only works on Time data, since the Spectral data is always scan averaged.

• ATMOSPHERE
  ATMOSPHERE is a new command to recompute the atmospheric calibration. This could formerly be done using the old SPECTRUM command.

• SOLVE FOCUS
  The FOCUS scans are now much like the POINTING scans: 3 scans are produced instead of 1 previously. The SOLVE FOCUS command accepts a /COMPRESS option to change the integration time of the Time data.

• SOLVE POINT
  The basic integration step being now 1 second, the sensitivity may be insufficient in such a time to allow the derivation of antenna based quantities from baseline visibilities in a pointing. SOLVE POINT command now accepts a /COMPRESS Time option to allow adjustment of the integration time of each dump to the source intensity. The default is /COMPRESS 4, producing something similar to the old correlator.

• SOLVE PSEUDO
  Because Time data can correspond to narrow bands, a pseudo-continuum mode is available for total-power pointing on strong line sources (SiO masers usually). If one subband group has been selected using command SET SUB, the signal is the intensity measured by this subband group. If two subband groups have bean selected (e.g. SET SUB C01 C02 TO C08 the signal from the second group is subtracted from that of the first group (which should thus contain the line emission) to produce true pseudo-continuum data.

• SOLVE DELAY
  The delay is no longer measured by scanning the delay line, but by measuring the phase slope as a function of frequency in the line subbands. The SOLVE DELAY/PLOT command will fit a straight line to the phase versus frequency (allowing for 2$\pi$ ambiguities).