Purpose
Given the pixel coordinates of an object on the LRIS slit guider,
compute and apply the required telescope move to bring the
object to the center of the slit guider detector.
Usage
gscent [-n] x y
Arguments
-n = no move, only print the required shift
x = column location of object [pixels]
y = row location of object [pixels]
Output
Exit values
0 = normal completion
1 = wrong number of arguments
Example
1) Move a target at pixel (100,200) to the red detector center
centr 100 200
2) Display the telescope move required to shift a target at
pixel (100,200) to the red detector center without moving the telecope
centr -n 100 200