diff --git a/c_tools/libzobov/particleInfo.cpp b/c_tools/libzobov/particleInfo.cpp
index 9711db6..fa6f467 100644
--- a/c_tools/libzobov/particleInfo.cpp
+++ b/c_tools/libzobov/particleInfo.cpp
@@ -10,6 +10,7 @@ bool loadParticleInfo(ParticleInfo& info,
 		      const std::string& extra_info)
 {
       int numpart;
+      int isObservation;
 
   NcFile f_info(extra_info.c_str());
  
@@ -23,6 +24,7 @@ bool loadParticleInfo(ParticleInfo& info,
   info.ranges[2][0] = f_info.get_att("range_z_min")->as_double(0);
   info.ranges[2][1] = f_info.get_att("range_z_max")->as_double(0);
   info.mask_index = f_info.get_att("mask_index")->as_int(0); //PMS
+  isObservation = f_info.get_att("is_observation")->as_int(0); //PMS
 
   for (int i = 0; i < 3; i++)
     info.length[i] = info.ranges[i][1] - info.ranges[i][0];
@@ -59,6 +61,14 @@ bool loadParticleInfo(ParticleInfo& info,
       for (int i = 0; i < numpart; i++)
 	info.particles[i].z = mul*f.readReal32();
       f.endCheckpoint();
+
+      if (!isObservation) {
+        for (int i = 0; i < numpart; i++) {
+	        info.particles[i].x += info.ranges[0][0];
+	        info.particles[i].y += info.ranges[1][0];
+	        info.particles[i].z += info.ranges[2][0];
+        }
+      }
     }
   catch (const NoSuchFileException& e)
     {
diff --git a/c_tools/mock/generateFromCatalog.cpp b/c_tools/mock/generateFromCatalog.cpp
index d5a0aca..54cbf87 100644
--- a/c_tools/mock/generateFromCatalog.cpp
+++ b/c_tools/mock/generateFromCatalog.cpp
@@ -466,6 +466,7 @@ void saveForZobov(ParticleData& pdata, const string& fname, const string& paramn
   fp.add_att("range_z_min", -Lmax/100.);
   fp.add_att("range_z_max", Lmax/100.);
   fp.add_att("mask_index", pdata.mask_index); // PMS
+  fp.add_att("is_observation", 1); // PMS
 
   int nOutputPart = pdata.mask_index;
   //int nOutputPart = pdata.pos.size();
diff --git a/c_tools/mock/generateMock.cpp b/c_tools/mock/generateMock.cpp
index a7830dd..fe21928 100644
--- a/c_tools/mock/generateMock.cpp
+++ b/c_tools/mock/generateMock.cpp
@@ -338,6 +338,7 @@ void saveBox(SimuData *&boxed, const std::string& outbox)
   f.add_att("range_z_min", ranges[4]);
   f.add_att("range_z_max", ranges[5]);
   f.add_att("mask_index", -1);
+  f.add_att("is_observation", 0);
 
   NcDim *NumPart_dim = f.add_dim("numpart_dim", boxed->NumPart);
   NcDim *NumSnap_dim = f.add_dim("numsnap_dim", num_snapshots);