Within the SB, a series of observations (the ultimate order of which will be determined by the observing script) are actually constructed out of Targets. These define an observation of a given source and are close to the concept of a scan, each of which might be repeated multiple times, most obviously for the science target and phase calibrator. A Target is constructed out of a Field Source, an Instrument Setup and an Observing Parameter - these are in turn refered to as Resources and are stored in a Resources folder.
The Targets themselves reside in their own folder and clicking on this will reveal a table listing various properties of each (Figure 6.2). Clicking on a Target will highlight the Resources that have been used to create it and will also show the Forms editors for each Resource together in the Editors panel. This takes up a lot of space and the OT should normally have its size maximised. A Target is created by either right-clicking on the SB or Targets folder and selecting the appropriate option, or via the Edit menu.
Freshly-created Targets are initially empty and their Resources need to be added. This can be done in two different ways, the most convenient of which is to view the Target via the Editors window. This will show three panels, for each of which an already defined Resource can be reused, or a new Resource created. If the latter is chosen, the newly-created Resource will need to be opened and the necessary information filled in. The second method is to attach and detach the Resources via right-clicking on the Target. This brings up a dialogue that shows all the pre-existing Resources in a column on the left, three of which need to be moved into the right column. Resources can also be independently created by clicking on the various Resource folders.
Each Target can only contain a single Field Source and Instrument Setup. It is technically possible to attach multiple Observing Parameters - some sources might be used for multiple calibrations for example - but this should not be done as the observing scripts cannot currently deal with this.
In order for a project to validate, it is necessary that one of the Targets be marked as the Representative Target - this is indicated with a [R] at the beginning of the Target's name. Note also that the names cannot be changed by the user as they follow a fixed format incorporating the source name and the observing intent (as set by the Observing Parameter). Targets without the three necessary Resources will cause a validation error.