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Rectangle

The parameters of the rectangle include the relative or absoluteposition, its length, width and position angle. They can be specifiedvia the rectangular shape icon on top of the image displaywindow. When clicking this button the cursor can be used to create arectangle and to determine the position, size and position angle -the rectangle can be resized by the blue handles and can be rotated bythe green handle. The parameters of the rectangle also fill the fieldsin the form at the right (in the Rectangle panel) and can alsobe specified here. Note that the contents of this panel are somewhatdifferent to those given in the Rectangle panel of a ScienceGoal. This is because the rectangle definition within an SB can alsobe used to perform a raster scan and not just to set up a mosaic. Theadditional parameters are Orthogonal Step , Scan Direction , Unidirectional Scan , Scan Velocity , and Scanning Coordinate System .

Figure 9.4: Example of a mosaic definition based on a rectangular pattern in an SB.
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The rectangular field pattern can be converted to a mosaic ofpointings. Click on the Setup Mosaic button in the Rectangle panel - this displays a new panel called Mosaic Parameters . The frequency is taken from the FOV Parameters panel below the image display and, as with there, is used to calculatethe antenna beamsize (primary beam) depending on the choice ofantenna, 12 m (ALMA) or 7 m (ACA). The default value of the spacing( Overlap ) is set to the Nyquist value of 50% of the antennabeamsize. Once the mosaic pattern has been chosen ( Layout Type ),the mosaic can be created using the Convert to Mosaic button. Aseries of telescope pointings with associated FOVs will be displayedon the editor filling the rectangle. An example of a mosaicspecification is given in Figure  9.4 .


next up previous contents index
Next: Other Field Patterns Up: Field Patterns for Scheduling Previous: Point   Contents   Index
The ALMA OT Team, 2011 May 20