Comment about iterative timestep

src/sorcha/ephemeris/simulation_setup.py

@@ -142,6 +142,7 @@ def generate_simulations(ephem, gm_sun, gm_total, orbits_df, args):
         sim = rebound.Simulation()
         sim.t = epoch - ephem.jd_ref
         sim.dt = 10
+        # This turns off the iterative timestep introduced in arXiv:2401.02849 and default since rebound 4.0.3
         sim.ri_ias15.adaptive_mode = 1
         # Add the particle to the simulation
         sim.add(ic)