getfits is a routine from wcstools that is extremely handy. In the example below I cut and image from columns 300 to 437 and rows 600 to 760. The figure shows the original and cut out images with the positions of NGC 4625 marked in each.

The original image name is:   n4618+4625_dss.fits
I make a new image called:   a.fits

I cut columns (X) =  300 to 437 
I cut rows    (Y) =  600 to 760 

getfits -o a.fits n4618+4625_dss.fits 300-437 600-760

FIGURE 1: A sample cutout. The nucleus of NGC4625 is located at the same RA,DEC in each case.