diff --git a/lisainstrument/instrument.py b/lisainstrument/instrument.py
index c59a8f723ff2c592f307d38878c3bdd7336588d3..96095d57dd86565bf53cbe0d173583af3ed6f255 100644
--- a/lisainstrument/instrument.py
+++ b/lisainstrument/instrument.py
@@ -251,11 +251,11 @@ class Instrument:
             orbitf = h5py.File(self.orbit_file, 'r')
             logging.debug("Interpolating proper pseudo-ranges")
             self.pprs = ForEachMOSA(lambda mosa: scipy.interpolate.InterpolatedUnivariateSpline(
-                orbitf['tcb']['t'][:], orbitf['tcb'][f'l_{mosa}']['ppr'], k=1, ext='raise')(self.physics_t)
+                orbitf['tcb']['t'][:], orbitf['tcb'][f'l_{mosa}']['ppr'], k=5, ext='raise')(self.physics_t)
             )
             logging.debug("Interpolating proper pseudo-range derivatives")
             self.d_pprs = ForEachMOSA(lambda mosa: scipy.interpolate.InterpolatedUnivariateSpline(
-                orbitf['tcb']['t'][:], orbitf['tcb'][f'l_{mosa}']['d_ppr'], k=1, ext='raise')(self.physics_t)
+                orbitf['tcb']['t'][:], orbitf['tcb'][f'l_{mosa}']['d_ppr'], k=5, ext='raise')(self.physics_t)
             )
             orbitf.close()
         elif orbits is None: