Taking the data

Observing must be stopped before carrying out the following. It is also advisable to close the correlator file

CAOBS$>$corr closefile.

You should note that the delay and phase calibration for the Array will be destroyed on those antennas to which the EARLY calibration is applied. This means you will need to run CACAL after you have completed the early/normal calibration.

To take the data, first ensure that the the correlator is set up to report auto-correlations (FULL_128_2 is the recommended correlator configuration), then type

CAOBS$>$early

to set up the correct scan type for taking the data. Then, on a xbones terminal, start the EARLY program

xbones$early.

The program will display a title message, the correlator products it will use and then will report that it is waiting for CAOBS to start. You should then start the Array tracking

CAOBS$>$track 1.

It doesn't matter what source it is, the early scan pattern will disable the antennas anyway. However, it is important that you choose a frequency that is actually 'on axis' at the time of the calibration. It is normal to do this calibration as a dual frequency operation.