diff --git a/iris/sg/__init__.py b/iris/sg/__init__.py
index 3b9d29a..3eb0ad3 100644
--- a/iris/sg/__init__.py
+++ b/iris/sg/__init__.py
@@ -8,5 +8,6 @@
 
 __all__ = [
     "background",
+    "effective_area",
     "SpectrographObservation",
 ]