diff --git a/cxx/mcc_erfa.h b/cxx/mcc_erfa.h
new file mode 100644
index 0000000..0a3ea32
--- /dev/null
+++ b/cxx/mcc_erfa.h
@@ -0,0 +1,44 @@
+#pragma once
+
+/*  MOUNT CONTROL COMPONENTS LIBRARY  */
+
+/*  ERFA-LIBRARY WRAPPER FUNCTIONS  */
+
+#include "mcc_mount_coord.h"
+
+namespace mcc::erfa
+{
+
+#include <erfa.h>
+#include <erfam.h>
+
+
+/*
+ * hour angle and declination to azimuth and altitude
+ *
+ */
+template <std::convertible_to<MccAngleHA> HaT,
+          std::convertible_to<MccAngleDEC_APP> DecT,
+          std::convertible_to<MccAngleLAT> LatT,
+          std::convertible_to<MccAngleAZ> AzT,
+          std::convertible_to<MccAngleALT> AltT>
+void hadec2azalt(const HaT& ha, const DecT& dec, const LatT& lat, AzT& az, AltT& alt)
+{
+    double az_d, alt_d;
+
+    eraHd2ae(ha, dec, lat, &az_d, &alt_d);
+    az = az_d;
+    alt = alt_d;
+}
+
+template <std::convertible_to<MccAngleHA> HaT,
+          std::convertible_to<MccAngleDEC_APP> DecT,
+          std::convertible_to<MccAngleLAT> LatT>
+MccAngle hadec2pa(const HaT& ha, const DecT& dec, const LatT& lat)
+{
+    return eraHd2pa(ha, dec, lat);
+}
+
+
+
+}  // namespace mcc::erfa