def simple_nbyn_hdu(n): return fits.PrimaryHDU(data=empty_nbyn(n), header=headers.generate_nxn_header(n))
def simple_3by3_hdu(): return fits.PrimaryHDU(data=simple_3by3(), header=headers.generate_nxn_header(3))
def centered_gaussian_hdu(): return fits.PrimaryHDU(data=centered_gaussian(), header=headers.generate_nxn_header(9))