diff --git a/scheduler/core/components/collector/__init__.py b/scheduler/core/components/collector/__init__.py
index 2ff01556..c765fd96 100644
--- a/scheduler/core/components/collector/__init__.py
+++ b/scheduler/core/components/collector/__init__.py
@@ -497,25 +497,26 @@ def time_accounting(self, site_plans: Plans) -> None:
             for v in plan.visits:
                 # Update Observation from Collector.
                 observation = self.get_observation(v.obs_id)
+                obs_seq = observation.sequence
                 # check that Observation is Observed
-                if v.atom_end_idx == len(observation.sequence)-1:
+                if v.atom_end_idx == len(obs_seq)-1:
                     observation.status = ObservationStatus.OBSERVED
                 else:
                     observation.status = ObservationStatus.ONGOING
-
+                      
                 # Update by atom in the sequence
-                for atom_idx, atom in enumerate(observation.sequence):
+                for atom_idx in range (v.atom_start_idx, v.atom_end_idx):
 
-                    atom.program_used = atom.prog_time
-                    atom.partner_used = atom.part_time
+                    obs_seq[atom_idx].program_used = obs_seq[atom_idx].prog_time
+                    obs_seq[atom_idx].partner_used = obs_seq[atom_idx].part_time
 
                     # Charge acquisition to the first atom
                     if atom_idx == 0:
                         if observation.obs_class == ObservationClass.PARTNERCAL:
-                            atom.program_used += observation.acq_overhead
+                            obs_seq[atom_idx].program_used += observation.acq_overhead
                         elif (observation.obs_class == ObservationClass.SCIENCE or
                               observation.obs_class == ObservationClass.PROGCAL):
-                            atom.program_used += observation.acq_overhead
+                            obs_seq[atom_idx].program_used += observation.acq_overhead
 
-                    atom.observed = True
-                    atom.qa_state = QAState.PASS
+                    obs_seq[atom_idx].observed = True
+                    obs_seq[atom_idx].qa_state = QAState.PASS
diff --git a/scheduler/core/components/optimizer/greedymax.py b/scheduler/core/components/optimizer/greedymax.py
index a2116e12..5bc7f1f8 100644
--- a/scheduler/core/components/optimizer/greedymax.py
+++ b/scheduler/core/components/optimizer/greedymax.py
@@ -30,6 +30,8 @@ class ObsPlanData:
     obs: Observation
     obs_start: datetime
     obs_len: int
+    atom_start: int
+    atom_end: int
     visit_score: float
 
 
@@ -820,6 +822,8 @@ def _add_visit(self, night, obs, max_group_info, best_interval, n_slots_filled)
             obs=obs,
             obs_start=start,
             obs_len=visit_length,
+            atom_start=atom_start,
+            atom_end=atom_end,
             visit_score=visit_score
         )
 
@@ -937,6 +941,8 @@ def output_plans(self, plans: Plans) -> None:
                     obs_in_plan = self.obs_in_plan[timeline.site][start_time_slot]
                     plans[timeline.site].add(obs_in_plan.obs,
                                              obs_in_plan.obs_start,
+                                             obs_in_plan.atom_start,
+                                             obs_in_plan.atom_end,
                                              start_time_slot,
                                              obs_in_plan.obs_len,
                                              obs_in_plan.visit_score)
diff --git a/scheduler/core/plans/__init__.py b/scheduler/core/plans/__init__.py
index 90076d07..17b225a8 100644
--- a/scheduler/core/plans/__init__.py
+++ b/scheduler/core/plans/__init__.py
@@ -196,13 +196,15 @@ def time2slots(time_slot_length: timedelta, time: timedelta) -> int:
     def add(self,
             obs: Observation,
             start: datetime,
+            atom_start: int,
+            atom_end: int,
             start_time_slot: int,
             time_slots: int,
             score: float) -> None:
         visit = Visit(start,
                       obs.id,
-                      obs.sequence[0].id,
-                      obs.sequence[-1].id,
+                      atom_start,
+                      atom_end,
                       start_time_slot,
                       time_slots,
                       score,