diff --git a/src/tdastro/astro_utils/opsim.py b/src/tdastro/astro_utils/opsim.py
index f147c3b..0b2f298 100644
--- a/src/tdastro/astro_utils/opsim.py
+++ b/src/tdastro/astro_utils/opsim.py
@@ -145,6 +145,9 @@ def __len__(self):
 
     def __getitem__(self, key):
         """Access the underlying opsim table."""
+        # Auto apply the colmap if possible.
+        if self.colmap is not None and key in self.colmap:
+            return self.table[self.colmap[key]]
         return self.table[key]
 
     @property
diff --git a/src/tdastro/example_runs/simulate_snia.py b/src/tdastro/example_runs/simulate_snia.py
index 44b24ab..6b6db7d 100644
--- a/src/tdastro/example_runs/simulate_snia.py
+++ b/src/tdastro/example_runs/simulate_snia.py
@@ -34,11 +34,11 @@ def draw_single_random_sn(
     obs_index = np.array(opsim.range_search(ra, dec, radius=1.75))
 
     # Update obs_index to only include observations within SN lifespan
-    phase_obs = opsim[opsim.colmap["time"]][obs_index] - t0
+    phase_obs = opsim["time"][obs_index] - t0
     obs_index = obs_index[(phase_obs > -20 * (1.0 + z)) & (phase_obs < 50 * (1.0 + z))]
 
-    times = opsim[opsim.colmap["time"]][obs_index].to_numpy()
-    filters = opsim[opsim.colmap["filter"]][obs_index].to_numpy(str)
+    times = opsim["time"][obs_index].to_numpy()
+    filters = opsim["filter"][obs_index].to_numpy(str)
     # Change to match band names in passbands object
     filters = np.char.add("LSST_", filters)