diff --git a/cxx/mcc_mount_concepts.h b/cxx/mcc_mount_concepts.h
index 71d1f6b..a4764c6 100644
--- a/cxx/mcc_mount_concepts.h
+++ b/cxx/mcc_mount_concepts.h
@@ -576,10 +576,10 @@ concept mcc_prohibited_zone_c =
         { t.timeFrom(std::declval<const TelemetryDataT&>()) } -> std::same_as<typename T::duration_t>;
     };
 
-// // an input range of prohibited zones
-// template <typename T, typename TelemetryDataT>
-// concept mcc_irange_of_pzones_c = mcc_mount_telemetry_data_c<TelemetryDataT> && std::ranges::input_range<T> &&
-//                                  mcc_prohibited_zone_c<std::ranges::range_value_t<T>, TelemetryDataT>;
+// an input range of prohibited zones
+template <typename T, typename TelemetryDataT>
+concept mcc_irange_of_pzones_c = mcc_mount_telemetry_data_c<TelemetryDataT> && std::ranges::input_range<T> &&
+                                 mcc_prohibited_zone_c<std::ranges::range_value_t<T>, TelemetryDataT>;
 
 
 // // a concept for a callable with the first argument of type satisfied to 'mcc_prohibited_zone_c'
diff --git a/cxx/mcc_mount_pz.h b/cxx/mcc_mount_pz.h
index ffe0191..fc50e6f 100644
--- a/cxx/mcc_mount_pz.h
+++ b/cxx/mcc_mount_pz.h
@@ -200,6 +200,39 @@ public:
         }
     }
 
+    // compute intersection point for the case of sideral-like moving
+    bool intersectPoint(traits::mcc_celestial_point_c auto const& target, traits::mcc_celestial_point_c auto& int_point)
+    {
+        coord_t ha, dec, az;
+
+        _coord2coord(target.coordPairKind, target.x, target.y, target.time_point,
+                     MccCoordPairKind::COORDS_KIND_HADEC_APP, ha, dec);
+
+        // compute HA for intersection point
+        double cos_ha =
+            (std::sin(_altLimit) - std::sin(dec) * std::sin(_latitude)) / std::cos(dec) / std::cos(_latitude);
+
+        if (cos_ha > 1.0) {  // no intersection
+            // compute culmination points?
+            return false;
+        }
+
+        double cosA = -sin(dec) * std::cos(_latitude) + std::cos(dec) * std::sin(_latitude) * cos_ha;
+        cosA /= std::cos(_altLimit);
+
+        if constexpr (KIND ==
+                      MccAltLimitKind::MIN_ALT_LIMIT) {  // the closest time point is one after upper culmination
+            az = std::acos(cosA);
+        } else if constexpr (KIND == MccAltLimitKind::MAX_ALT_LIMIT) {  // the closest time point is one before upper
+                                                                        // culmination
+            az = -std::acos(cosA);
+        }
+
+        _coord2coord(MccCoordPairKind::COORDS_KIND_AZALT, az, _altLimit, target.time_point, int_point.coordPairKind,
+                     int_point.x, int_point.y);
+
+        return true;
+    }
 
 private:
     coord_t _altLimit, _latitude, _abs_lat, _lat_lim;
@@ -274,13 +307,14 @@ private:
         }
 
         double ha;
+        // WARNING: what about south hemisphere?!!!
         if (before_upper_culm) {
             ha = -std::acos(cos_ha);  // HA before upper culmination
         } else {
             ha = std::acos(cos_ha);  // HA after upper culmination!!
         }
 
-        MccAngle time_ang = ha - ha_app;  // in sideral time scale
+        coord_t time_ang = ha - ha_app;  // in sideral time scale
 
         if (time_ang < 0.0) {  // next day
             time_ang += pi2;
diff --git a/cxx/mcc_mount_telemetry.h b/cxx/mcc_mount_telemetry.h
index b6a2a7b..0a9574b 100644
--- a/cxx/mcc_mount_telemetry.h
+++ b/cxx/mcc_mount_telemetry.h
@@ -296,7 +296,7 @@ public:
             ast_err = this->_astromEngine.hadec2pa(current_data.mntHA, current_data.mntDEC, current_data.mntPA);
             if (!ast_err) {
                 // target coordinates (assuming its ICRS RA-DEC are already given or computed)
-                typename mount_telemetry_data_t::eo_t eo;
+                typename astrom_engine_t::eo_t eo;
                 ast_err = this->_astromEngine.icrs2obs(current_data.tagRA_ICRS, current_data.tagDEC_ICRS,
                                                        current_data.jd, current_data.tagRA, current_data.tagDEC,
                                                        current_data.tagHA, current_data.tagAZ, current_data.tagALT, eo);
diff --git a/cxx/mcc_mount_telemetry_astrom.h b/cxx/mcc_mount_telemetry_astrom.h
index dd4567a..2e6a76b 100644
--- a/cxx/mcc_mount_telemetry_astrom.h
+++ b/cxx/mcc_mount_telemetry_astrom.h
@@ -117,13 +117,11 @@ public:
 
     MccMountTelemetryAstromTransform& operator=(MccMountTelemetryAstromTransform&& other)
     {
-        if (this == &other) {
-            return;
+        if (this != &other) {
+            _pec = other._pec;
+            _astromEngine = other._astromEngine;
         }
 
-        _pec = other._pec;
-        _astromEngine = other._astromEngine;
-
         return *this;
     }
 
@@ -134,13 +132,11 @@ public:
 
     MccMountTelemetryAstromTransform& operator=(const MccMountTelemetryAstromTransform& other)
     {
-        if (this == &other) {
-            return;
+        if (this != &other) {
+            _pec = other._pec;
+            _astromEngine = other._astromEngine;
         }
 
-        _pec = other._pec;
-        _astromEngine = other._astromEngine;
-
         return *this;
     }
 
diff --git a/cxx/tests/astrom_test.cpp b/cxx/tests/astrom_test.cpp
index e430c5c..d40394e 100644
--- a/cxx/tests/astrom_test.cpp
+++ b/cxx/tests/astrom_test.cpp
@@ -163,7 +163,7 @@ int main(int argc, char* argv[])
 
     // std::cout << "\n\n\n\n";
 
-    using engine_t = mcc::astrom::erfa::MccMountAstromEngineERFA<>;
+    using engine_t = mcc::astrom::erfa::MccMountAstromEngineERFA;
     engine_t::engine_state_t state;
     state.lon = 41.440732_degs;
     state.lat = 43.646711_degs;