The choice of this location was provided by Mark Robinson in his early analysis of the data. The "clean" area of the detector is a rectangular region with the following coordinates:
Starting Line = 33
Starting Sample = 179
Number of Lines = 100
Number of Samples = 210
Note that these numbers assume that the first pixel in the image has a coordinate of line 0, sample 0. In addition, some confusion comes into play when images are displayed in IDL since it displays pixel(0,0) in the lower left corner, unlike most other image display programs.