from pyraf import iraf

def compare(im1, im2, imtmp="../mwv.fits"):
    iraf.imdelete(imtmp)
    iraf.imarith(im1, "-", im2, imtmp)
    iraf.display(imtmp,2)
    iraf.imexam()

def check(objnum):
    im1="obj_%03d" % (objnum  )
    im2="obj_%03d" % (objnum-1)
    compare(im1, im2)