diff --git a/agasc/supplement/magnitudes/star_obs_catalogs.py b/agasc/supplement/magnitudes/star_obs_catalogs.py
index 00c47ad7..e69d8405 100644
--- a/agasc/supplement/magnitudes/star_obs_catalogs.py
+++ b/agasc/supplement/magnitudes/star_obs_catalogs.py
@@ -44,7 +44,7 @@ def get_star_observations(start=None, stop=None, obsid=None):
 
     star_obs.add_index(['mp_starcat_time'])
 
-    max_time = CxoTime(events.dwells.all().table[-1]['stop'])
+    max_time = events.dwells.all().latest('tstart').stop
     star_obs = star_obs[star_obs['obs_start'] <= max_time]
 
     return star_obs