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ACS pointing patterns

ACS-WFC-MOSAIC-BOX
pointing patterns

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This is a two-dimensional mosaic pattern, with the following allowable parameter ranges:

     Pattern_Number: 1 
       Pattern_Type: ACS-WFC-MOSAIC-BOX
    Pattern_Purpose: MOSAIC
   Number_Of_Points: 4
      Point_Spacing: 10.0 - 130.0 (arcseconds)
       Line_Spacing: 10.0 - 130.0 (arcseconds)
   Coordinate_Frame: POS-TARG
     Pattern_Orient: 0.0 - 360.0  (degrees)     
Angle_Between_Sides: 0.0 - 360.0  (degrees) 
     Center_Pattern: ?            (YES or NO)

Note: When mosaicking in a sparse field, where there may be too few objects in the overlap regions to help register the resulting images, the shifts in the patterns below should be reduced to increase the overlap area. Images taken with the same guide stars will register well just using the WCS, but where a guide star handoff occurs, the WCS will be inadequate for image registration, and the shifts will need to be measured using the relative positions of objects in the overlap regions.


The pattern displayed above has a ~full-FOV shift in x, but only a ~half-FOV shift in y, which covers the interchip gap, and can be done with one guide star pair. This pattern cannot currently be executed with a pattern form due to guide star handoffs needed for the x-shifts (which exceed ~100 arcsec). The POS TARG equivalents must be used for now:
     Pattern_Number: 18
       Pattern_Type: ACS-WFC-MOSAIC-BOX
    Pattern_Purpose: MOSAIC
   Number_Of_Points: 4
      Point_Spacing: 96.231
       Line_Spacing: 192.884
   Coordinate_Frame: POS-TARG
     Pattern_Orient: 90.0
Angle_Between_Sides: 99.0
     Center_Pattern: YES
POS TARG equivalent:  -96.108, -55.898
                      -96.108,  40.334
                       96.108,  55.898
                       96.108, -40.334

The full mosaic shift pattern (displayed here) cannot be executed with a pattern form due to guide star handoffs (both the x and y shifts exceed ~100 arcsec). The POS TARG equivalents must be used for now.
     Pattern_Number: 17
       Pattern_Type: ACS-WFC-MOSAIC-BOX
    Pattern_Purpose: MOSAIC
   Number_Of_Points: 4
      Point_Spacing: 192.215
       Line_Spacing: 192.844
   Coordinate_Frame: POS-TARG
     Pattern_Orient: 90.00
Angle_Between_Sides: 94.63
     Center_Pattern: YES
POS TARG equivalent:  -96.108, -103.890
                      -96.083,   88.303
                       96.108,  103.890
                       96.108,  -88.326

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