ACS-SBC-DITHER-BOX

This is a two-dimensional 4-point dither pattern, with the following allowable parameter ranges:

     Pattern_Number: 1 
       Pattern_Type: ACS-SBC-DITHER-BOX
    Pattern_Purpose: DITHER
   Number_Of_Points: 4
      Point_Spacing: 0.01 - 10.0 (arcseconds)
       Line_Spacing: 0.01 - 10.0 (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)

The following versions of this Pattern_Type are projected onto the detector pixel space in the graphic above.

The default pattern has relative pixel coordinates
(0, 0), (5.0, 1.5), (2.5, 4.5), (-2.5, 3.0).
It is a parallelogram pattern designed for half-pixel sampling in both x and y, with overall dimensions large enough to help reject the larger detector artifacts.

     Pattern_Number: 36
       Pattern_Type: ACS-SBC-DITHER-BOX
    Pattern_Purpose: DITHER
   Number_Of_Points: 4
      Point_Spacing: 0.179
       Line_Spacing: 0.116
   Coordinate_Frame: POS-TARG
     Pattern_Orient: 20.02
Angle_Between_Sides: 63.65
     Center_Pattern: NO

POS TARG equivalent:  0.000,  0.000
                      0.168,  0.062
                      0.084,  0.143
                     -0.084,  0.082