Different calibration types may use the same calibrator source. Thus, calibration targets in the Target folder may share the same FieldSource, but have different SpectralSpecs and Observing Parameters. Similarly, different calibration Targets may have the same SpectralSpec attached.
To add calibration Targets to an SB that already contains one or more science Targets, the Calibration Selection Tool can be useful. First select a science Target and then in the OT Menu select
Tools
ALMA Calibration Selection Tool
. If the position of the science Target has been specified (in an attached FieldSource) the Calibrator Selection Tool GUI will display the RA and Dec coordinates. Otherwise, the coordinate fields will be zero and the user has to provide these. Next, the maximum distance to the science Target shall be defined. Also, the fields for
Frequency
and
Flux density
specification can be filled. With the
Calibrator Tag
field the user can optimise the search for a particular calibrator type. Use the
Submit Query
button to select all calibration sources that fulfill the specifications. From this list of calibrators, select one by clicking in the table.
After having selected the calibrator, the Select As ... button provides you with a dialogue box. The dialogue box consist of two parts. With Calibrator type one can specify for which calibrations the selected calibrator is to be used (amplitude, phase, etc.). On the right the user can specify which SpectralSpecshould be attached to the calibration Target.
For the selected calibrator, the Calibration Tool will add one Target to the Target folder and attach a FieldSource and an Observing Parameters set.On the right in the dialog box, Copy to new setup will create a copy of the scienceTarget's SpectralSpec and attach this to the calibration Target. Link to same setup will attach the science SpectralSpec to the calibration Target. Do nothing will not create a SpectralSpec for the calibration target. Note that a SpectralSpec can only be copied or created when it exists. To create a SpectralSpec please refer to the next section.
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An example of a calibration setup created by the Calibration Tool is displayed in Figure 8.4 . In the Project tree, one science Target has been defined (HD163296). In the Calibration Tool, J1820-254 was selected for doing phase calibrations. NRAO530 is used for pointing, focus, bandpass and amplitude calibration. For the case of the bandpass calibration, the Copy to new option was selected to replicate the SpectralSpec of the science Target and attach it the calibration Target. In the Observing Parameters folder, parameter sets are created for the different calibration types. By selecting the calibration Target, all forms attached to the calibration Target are highlighted.
When clicking on the Target folder, the Editor pane shows a table with a summary of the current Targets. For an example, see Figure 8.5 . Similar tables can be displayed for the Instrument Setup and Observing Parameters folders.