diff --git a/generate/template/astronomy.py b/generate/template/astronomy.py
index 605a5b1e..3d25a289 100644
--- a/generate/template/astronomy.py
+++ b/generate/template/astronomy.py
@@ -160,6 +160,9 @@ class astro_time_t:
         self.ut = ut
         self.tt = _TerrestrialTime(ut)
 
+    def AddDays(self, days):
+        return astro_time_t(self.ut + days)
+
 _EPOCH = datetime.datetime(2000, 1, 1, 12)
 
 def CurrentTime():
diff --git a/source/python/astronomy.py b/source/python/astronomy.py
index cc774c49..651cdcf8 100644
--- a/source/python/astronomy.py
+++ b/source/python/astronomy.py
@@ -251,6 +251,9 @@ class astro_time_t:
         self.ut = ut
         self.tt = _TerrestrialTime(ut)
 
+    def AddDays(self, days):
+        return astro_time_t(self.ut + days)
+
 _EPOCH = datetime.datetime(2000, 1, 1, 12)
 
 def CurrentTime():