SXT_CENTER calculates the row (x) and column (y) of the
center of the solar disk and the radius (r) of the Sun
given a data cube (data) and the index structure (index).
The routine performs a fit to the limbs of the image. The fit can
be off by several pixels in the E/W direction for X-ray images.
See the SXC database if you are interested in the X-ray center
for all SFD images as calculated by SXT_CENTER.
IDL> sxt_center,data,index,x,y,r
There are many options that are possible to use, please
check them with DOC_LIBRARY.