diff --git a/lisainstrument/instrument.py b/lisainstrument/instrument.py
index f0ce39d9997beccec6af36267386b27a1ec17b7f..6fc400cd95ecc3067834112c21f1b9f2acf6d475 100644
--- a/lisainstrument/instrument.py
+++ b/lisainstrument/instrument.py
@@ -94,8 +94,9 @@ class Instrument:
                 or None for no filter; to design a filter from a Kaiser window, use a tuple
                 ('kaiser', attenuation [dB], f1 [Hz], f2 [Hz]) with f1 < f2 the frequencies defining
                 the transition band
-            orbits: path to orbit file, dictionary of constant PPRs for static arms, or 'static'
-                for a set of static PPRs corresponding to a fit of Keplerian orbits around t = 0
+            orbits: path to orbit file, dictionary of constant PPRs for static arms, 'static'
+                for a set of static PPRs corresponding to a fit of Keplerian orbits around t = 0,
+                or dictionary of PPR time series
             gws: path to gravitational-wave file, or dictionary of gravitational-wave responses
             interpolation: interpolation function or interpolation method and parameters;
                 use a tuple ('lagrange', order) with `order` the odd Lagrange interpolation order;