diff --git a/src/tdastro/pipeline.py b/src/tdastro/pipeline.py
new file mode 100644
index 0000000..52fe8ab
--- /dev/null
+++ b/src/tdastro/pipeline.py
@@ -0,0 +1,27 @@
+"""Utilities for running the simulation pipeline."""
+
+
+import numpy as np
+
+
+def apply_noise(flux, flux_err, rng=None):
+    """Apply Gaussian noise to a flux measurement.
+
+    Parameters
+    ----------
+    flux : ndarray of float
+        The flux measurement.
+    flux_err : ndarray of float
+        The flux measurement error.
+    rng : np.random.Generator, optional
+        The random number generator.
+
+    Returns
+    -------
+    ndarray of float
+        The noisy flux measurement.
+    """
+    if rng is None:
+        rng = np.random.default_rng()
+
+    return rng.normal(loc=flux, scale=flux_err)