options to disable sky model, and read noise, bias, and dark current

data/default_imsim_configs

@@ -4,6 +4,10 @@ dark_current = 0.02
 bias_level = 1000.
 pcti = 1e-6
 scti = 1e-6
+disable_readnoise_bias_darkcurrent = False
+
+[sky_model]
+disable_sky_model = False
 
 [ccd]
 full_well = 1e5

python/desc/imsim/ImageSimulator.py

@@ -130,9 +130,11 @@ def _make_gs_interpreters(self, seed, sensor_list, file_id):
         InstCatTrimmer object in gs_obj_dict can be recovered.
         """
         bp_dict = BandpassDict.loadTotalBandpassesFromFiles(bandpassNames=self.obs_md.bandpass)
+        disable_sky_model = self.config['sky_model']['disable_sky_model']
         noise_and_background \
             = make_sky_model(self.obs_md, self.phot_params, seed=seed,
-                             apply_sensor_model=self.apply_sensor_model)
+                             apply_sensor_model=self.apply_sensor_model,
+                             disable_sky_model=disable_sky_model)
         self.gs_interpreters = dict()
         for det in self.camera_wrapper.camera:
             det_type = det.getType()

python/desc/imsim/camera_readout.py

@@ -38,7 +38,6 @@
 __all__ = ['ImageSource', 'set_itl_bboxes', 'set_e2v_bboxes',
            'set_phosim_bboxes', 'set_noao_keywords', 'cte_matrix']
 
-config = get_config()
 class ImageSource(object):
     '''
     Class to create single segment images based on the pixel geometry
@@ -85,6 +84,8 @@ def __init__(self, image_array, exptime, sensor_id, visit=42, logger=None):
         else:
             self.logger = logger
 
+        self.config = get_config()
+
         self.eimage = fits.HDUList()
         self.eimage.append(fits.PrimaryHDU(image_array))
         self.eimage_data = self.eimage[0].data.transpose()
@@ -259,6 +260,9 @@ def _make_amp_images(self):
         for amp_name in amp_names:
             self._make_amp_image(amp_name)
         self._apply_crosstalk()
+        if self.config['electronics_readout']\
+           ['disable_readnoise_bias_darkcurrent']:
+            return
         for amp_name in amp_names:
             self._add_read_noise_and_bias(amp_name)
 
@@ -291,8 +295,9 @@ def _make_amp_image(self, amp_name):
         imaging_segment.getArray()[:] = data
 
         # Add dark current.
-        if self.exptime > 0:
-            dark_current = config['electronics_readout']['dark_current']
+        if (self.exptime > 0 and not self.config['electronics_readout']
+            ['disable_readnoise_bias_darkcurrent']):
+            dark_current = self.config['electronics_readout']['dark_current']
             imaging_arr = imaging_segment.getArray()
             rng = galsim.PoissonDeviate(seed=self.rng,
                                         mean=dark_current*self.exptime)
@@ -304,12 +309,12 @@ def _make_amp_image(self, amp_name):
 
         # Apply CTE.
         full_arr = full_segment.getArray()
-        pcti = config['electronics_readout']['pcti']
+        pcti = self.config['electronics_readout']['pcti']
         pcte_matrix = cte_matrix(full_arr.shape[0], pcti)
         for col in range(0, full_arr.shape[1]):
             full_arr[:, col] = np.dot(pcte_matrix, full_arr[:, col])
 
-        scti = config['electronics_readout']['scti']
+        scti = self.config['electronics_readout']['scti']
         scte_matrix = cte_matrix(full_arr.shape[1], scti)
         for row in range(0, full_arr.shape[0]):
             full_arr[row, :] = np.dot(scte_matrix, full_arr[row, :])
@@ -336,7 +341,7 @@ def _add_read_noise_and_bias(self, amp_name):
         rn_data = np.zeros(np.prod(full_arr.shape))
         rng.generate(rn_data)
         full_arr += rn_data.reshape(full_arr.shape)
-        full_arr += config['electronics_readout']['bias_level']
+        full_arr += self.config['electronics_readout']['bias_level']
 
     @property
     def rng(self):

python/desc/imsim/skyModel.py

@@ -19,8 +19,10 @@
 
 def make_sky_model(obs_metadata, photParams, seed=None, bandpassDict=None,
                    addNoise=True, addBackground=True, apply_sensor_model=False,
-                   logger=None, fast_silicon=True):
+                   logger=None, fast_silicon=True, disable_sky_model=False):
     "Function to provide ESOSkyModel object."
+    if disable_sky_model:
+        return NullSkyModel()
     if apply_sensor_model:
         if fast_silicon:
             return FastSiliconSkyModel(obs_metadata, photParams,
@@ -117,6 +119,18 @@ def get_chip_center(chip_name, camera):
 
     return center_x, center_y
 
+class NullSkyModel(NoiseAndBackgroundBase):
+    def __init__(self):
+        pass
+
+    def addNoiseAndBackground(self, image, **kwds):
+        return image
+
+    def getNoiseModel(self, **kwds):
+        raise NotImplementedError("This should not be called.")
+
+    def sky_counts(self, chipName):
+        return 0
 
 class ESOSkyModel(NoiseAndBackgroundBase):
     """