diff --git a/src/sed/calibrator/momentum.py b/src/sed/calibrator/momentum.py
index 534ad81f..75b7425f 100644
--- a/src/sed/calibrator/momentum.py
+++ b/src/sed/calibrator/momentum.py
@@ -102,7 +102,7 @@ def __init__(
         self.include_center: bool = False
         self.use_center: bool = False
         self.pouter: np.ndarray = None
-        self.pcent: tuple[float, ...] = None
+        self.pcent: tuple[float, float] = None
         self.pouter_ord: np.ndarray = None
         self.prefs: np.ndarray = None
         self.ptargs: np.ndarray = None