from astropy.io import fits
import numpy as np

def prepare(in_path, out_path):
   h = fits.open(in_path)
   for i in [1,2,3,4]:
      h[i].data = h[i].data * 10 ** (-0.4 * (h[i].header['MAGZPT'] - 23.0))
   h.writeto(out_path, overwrite=True)
   h_wei = h.copy()
   #h.close()
   for i in [1,2,3,4]:
      h_wei[i].data = np.ones(h[i].data.shape)
      h_wei[i].data[h[i].data == 0] = 0
   h_wei.writeto(out_path.replace('.fit', '.weight.fit'), overwrite=True)