add gc for straylight model

ObservationSim/Instrument/Filter.py

@@ -2,6 +2,7 @@ import galsim
 import pylab as pl
 import os
 import numpy as np
+import gc
 
 from ObservationSim.Instrument._util import photonEnergy, calculateLimitMag
 from ObservationSim.Instrument.FilterParam import FilterParam
@@ -120,6 +121,9 @@ class Filter(object):
             self.sky_background = s_pix
             self.zodical_spec = None
 
+        del sl
+        gc.collect()
+
     def update_limit_saturation_mags(self, exptime=150., psf_fwhm=0.1969, skyFn='sky_emiss_hubble_50_50_A.dat', chip=None):
         if self.filter_type in ["GI", "GV", "GU"]:
             return