Positioner Control

The Positioner Control window is shown in Figure . The top section of the display shows that the plate in the configuring position (Config Plate) is currently field plate 0. This means that plate 1 is in the observing position. The last configuration file which each plate was set up with is shown below this. You can double click on the file name to get further details on the configuration file.

Figure: The Positioner Control window -- This is obtained by clicking on the more button in the Positioner section of the main Control Task. window

The Fibres Moved? button indicates if any fibres have been moved since the field was set up. The All Parked button will be on if all the fibres on the plate are parked.

The lower section of the display is a `notebook' widget with most of the main positioner control functions in the Plate0 page (and duplicated in the Plate1 page).

The Survey... button starts a survey of the grid of fiducial marks in the field plate. This calibrates the relationship between the encoder units of the gripper or FPI gantry with the actual XY of the field plate. A field plate survey should be done before any position critical operations are done with a gantry, such as setting up a field (a survey is now done automatically when a field is setup), or doing an astrometric calibration with the FPI. Because of flexure between the gantries and field plates, the survey should be done at the same telescope position at which the setup or calibration will be done. The Survey... button brings up a dialogue which allows selection of the FPI or Gripper gantry and provides options for a number of different types of survey. The All option is the one normally used for calibration.

The Tumble button `tumbles' the positioner interchanging the positions of the two field plates. The plate that was at the configuring position now becomes the observing plate. This also changes the slit within the AAOmega spectrograph. However, the slit will not start to change until after CCD readout is complete (to prevent scattered light from encoders on the motors from contaminating data).

The Configure Fibres button initiates the setting up of a fibre configuration. The configuration file to be set up should be entered in the Config file entry section. Clicking on the button at the right hand end of this will bring up a file section dialogue to enable the file to be selected.

By default configuration files are `tweaked' before being set up. This involves recalculating the XY positions of the fibres for a specified observing time and for the current astrometric model and refraction parameters (Weather)). If you are going to tweak your file make sure that the information in the Weather and Wavelengths pages are correctly set up as these are used for the refraction calculation. The Obs Time value is used to set the time in minutes from now which the field will be set up for, or for a given local time. If you turn off tweaking (though why you would want to do this, we can't imagine), the XY values in the configuration file will be used (which may have been calculated using an old model). It's hard to imagine a situation where you would want to disable tweaking.

Once the field setup starts, the Configuration Progress section displays a progress bar, and the number of the fibre currently being positioned. The Configure Fibres will then change to an Abort setup button.

The Park All button parks all the fibres on the plate.

The Fibre Moves page contains options to move or park individual fibres.