Pulsar bin-mode observations

When observing pulsars with the ATCA, the correlator is capable of sampling synchronously with a pulsar. In this way, during a single integration, the correlator will produce a number of bins, each of which sample at a particular range in phase of the pulsar cycle. Much of the time, when reducing a bin-mode experiment, you will want to process all the bins without regard to the bin number. In this case, to a large degree, processing a bin-mode observation differs little from a normal observation. In particular:

• No special action is needed in loading the data with atlod.
• During the flagging process, tasks tvflag and blflag will simply average together all the pulsar bins before display. When you flag a point on the display as bad, all the bins which are used to generate that point are flagged as bad.
• Generally the calibrators in such an experiment will be observed in a binning mode. The calibration software combines the different bins together before determining their calibration solutions.

Obviously, however, there are times that you will want to distinguish between the bins. The bin visibility selection sub-command is the main mechanism for this. The general form is:

select=bin(n1,n2)

This selects bins n1 to n2 inclusive. If only a single bin is given, then only that bin is selected - numbering of the bins starts at 1.

The most common places where you will want to select a subset of bins is in the imaging and possibly self-calibration steps (the pulsar, during its `on' phase, may make an excellent phase self-calibration source).

Although almost all visibility-data tasks support bin-mode observations, there are a few exceptions. These give warnings when they are used on bin-mode data. These warnings should be heeded!. The most notable task which fails to properly handle bin-mode experiments is uvaver when time averaging of the data is being performed. When used to time-average, uvaver will average all the bins together. Note, however, that uvaver works correctly (i.e. treating the bins as separate) when no time averaging is involved.