OCENTER will obtain the center of the Sun from a optical full frame image.
It makes a ``silhouette image'' consisting of 1's and 0's, then
calculates the centroid to determine 
and 
. The area is used to
determine the image radius. The input image can be compressed
or decompressed, and in any summation mode. The output is in SXT full resolution
pixels unless /noscale is set.
IDL> ocenter, image, x, y, radius
IDL> ocenter, image, x, y, radius, /noscale, cut=0.3
where image is the 2-D input image, and x and y are the
E/W and N/S position of the sun. radius is the solar radius in
pixels and cut is the fraction of image maximum to define the limb (default is 0.2)