Fix error propagation for inverse correction

spacetelescope · Jan 31, 2025 · a817c79 · a817c79
1 parent 0641e67
commit a817c79
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Showing 2 changed files with 14 additions and 5 deletions.
diff --git a/jwst/barshadow/bar_shadow.py b/jwst/barshadow/bar_shadow.py
@@ -78,13 +78,18 @@ def do_correction(
         #     because they're variance, while err is standard deviation
         if not inverse:
             slitlet.data /= correction.data
+            slitlet.err /= correction.data
+            slitlet.var_poisson /= correction.data**2
+            slitlet.var_rnoise /= correction.data**2
+            if slitlet.var_flat is not None and np.size(slitlet.var_flat) > 0:
+                slitlet.var_flat /= correction.data**2
         else:
             slitlet.data *= correction.data
-        slitlet.err /= correction.data
-        slitlet.var_poisson /= correction.data**2
-        slitlet.var_rnoise /= correction.data**2
-        if slitlet.var_flat is not None and np.size(slitlet.var_flat) > 0:
-            slitlet.var_flat /= correction.data**2
+            slitlet.err *= correction.data
+            slitlet.var_poisson *= correction.data**2
+            slitlet.var_rnoise *= correction.data**2
+            if slitlet.var_flat is not None and np.size(slitlet.var_flat) > 0:
+                slitlet.var_flat *= correction.data**2
         slitlet.barshadow = correction.data
 
     return output_model, corrections

diff --git a/jwst/barshadow/tests/test_barshadow_step.py b/jwst/barshadow/tests/test_barshadow_step.py
@@ -160,6 +160,10 @@ def test_barshadow_correction_pars(nirspec_mos_model):
 
     # output data is the same as input, except that NaNs do not invert
     assert np.allclose(inverse_result.slits[0].data[nnan], model.slits[0].data[nnan])
+    assert np.allclose(inverse_result.slits[0].err[nnan], model.slits[0].err[nnan])
+    assert np.allclose(inverse_result.slits[0].var_rnoise[nnan], model.slits[0].var_rnoise[nnan])
+    assert np.allclose(inverse_result.slits[0].var_poisson[nnan], model.slits[0].var_poisson[nnan])
+    assert np.allclose(inverse_result.slits[0].var_flat[nnan], model.slits[0].var_flat[nnan])
 
     result.close()
     inverse_result.close()