diff --git a/mcc/mcc_ccte_erfa_new.h b/mcc/mcc_ccte_erfa_new.h
index 99ff537..c8aab44 100644
--- a/mcc/mcc_ccte_erfa_new.h
+++ b/mcc/mcc_ccte_erfa_new.h
@@ -282,11 +282,32 @@ public:
     error_t obs2icrs(mcc_coord_pair_c auto const& xy_obs, MccSkyRADEC_ICRS* radec_icrs) {}
 
 
-    error_t equationOrigins(const mcc_julday_c auto& MJD, mcc_angle_c auto* EO)
+    error_t equationOrigins(const mcc_julday_c auto& mjd, mcc_angle_c auto* eo)
     {
-        if (EO == nullptr) {
+        if (eo == nullptr) {
             return MccCCTE_ERFAErrorCode::ERROR_NULLPTR;
         }
+
+        error_t ret = MccCCTE_ERFAErrorCode::ERROR_OK;
+
+        std::lock_guard lock{*_stateMutex};
+
+        using real_days_t = std::chrono::duration<double, std::ratio<86400>>;
+
+        auto tai_utc = _currentState._leapSeconds[mjd];
+        if (tai_utc.has_value()) {
+            double tt = mjd;
+            tt += std::chrono::duration_cast<real_days_t>(tai_utc.value()).count();
+
+            auto tt_tai = _currentState._bulletinA.TT_TAI();
+            tt += +std::chrono::duration_cast<real_days_t>(tt_tai).count();
+
+            *eo = eraEo06a(ERFA_DJM0, tt);
+        } else {
+            ret = MccCCTE_ERFAErrorCode::ERROR_LEAPSECONDS_OUT_OF_RANGE;
+        }
+
+        return ret;
     }
 
     // refraction