fix header checksum issue; update straylight mode PSF file

ObservationSim/sim_steps/readout_output.py

@@ -82,17 +82,16 @@ def quantization_and_output(self, chip, filt, tel, pointing, catalog, obs_param)
     
     
     hdu1 = fits.PrimaryHDU(header=self.h_prim)
-    hdu1.add_checksum()
-    hdu1.header.comments['CHECKSUM'] = 'HDU checksum'
-    hdu1.header.comments['DATASUM'] = 'data unit checksum'
-    self.updateHeaderInfo(header_flag='ext', keys = ['DATASECT'], values = [str(chip.img.array.shape[1])+'x'+str(chip.img.array.shape[0])])
+ 
+    self.updateHeaderInfo(header_flag='ext', keys = ['DATASECT'], values = [str(chip.img.array.shape[1]) + 'x' + str(chip.img.array.shape[0])])
     hdu2 = fits.ImageHDU(chip.img.array, header=self.h_ext)
-    hdu2.add_checksum()
-    hdu2.header.comments['XTENSION'] = 'extension type'
-    hdu2.header.comments['CHECKSUM'] = 'HDU checksum'
-    hdu2.header.comments['DATASUM'] = 'data unit checksum'
     hdu2.header.comments["XTENSION"] = "image extension"
-    hdu1 = fits.HDUList([hdu1, hdu2])
-    hdu1.writeto(fname, output_verify='ignore', overwrite=True)
+    
+    hdu = fits.HDUList([hdu1, hdu2])
+    hdu[0].add_datasum(when='data unit checksum')
+    hdu[0].add_checksum(when='HDU checksum', override_datasum=True)
+    hdu[1].add_datasum(when='data unit checksum')
+    hdu[1].add_checksum(when='HDU checksum', override_datasum=True)
+    hdu.writeto(fname, output_verify='ignore', overwrite=True)
 
     return chip, filt, tel, pointing