diff --git a/mcc_constants.h b/mcc_constants.h
index 4e521f1..83ac488 100644
--- a/mcc_constants.h
+++ b/mcc_constants.h
@@ -18,11 +18,11 @@
 namespace mcc
 {
 
-constexpr double MCC_DEGRESS_TO_RADS = std::numbers::pi / 180.0;
-constexpr double MCC_RADS_TO_DEGRESS = 1.0 / MCC_DEGRESS_TO_RADS;
+static constexpr double MCC_DEGRESS_TO_RADS = std::numbers::pi / 180.0;
+static constexpr double MCC_RADS_TO_DEGRESS = 1.0 / MCC_DEGRESS_TO_RADS;
 
-constexpr double MCC_HALF_PI = std::numbers::pi / 2.0;
-constexpr double MCC_TWO_PI = std::numbers::pi * 2.0;
+static constexpr double MCC_HALF_PI = std::numbers::pi / 2.0;
+static constexpr double MCC_TWO_PI = std::numbers::pi * 2.0;
 
 static constexpr double MCC_SIDERAL_TO_UT1_RATIO = 1.002737909350795;  // sideral/UT1
 
diff --git a/mcc_coordinate.h b/mcc_coordinate.h
index b0ea315..3378235 100644
--- a/mcc_coordinate.h
+++ b/mcc_coordinate.h
@@ -659,30 +659,30 @@ protected:
     // HA, DEC to AZ, ALT (AZ from the South through the West)
     void hadec2azalt(double ha, double dec, double phi, double& az, double& alt) const
     {
-        eraHd2ae(ha, dec, phi, &az, &alt);
-        // from ERFA "from N" to "from S"
-        if (az > std::numbers::pi) {
-            az -= std::numbers::pi;
-        } else {
-            az += std::numbers::pi;
-        }
+        // eraHd2ae(ha, dec, phi, &az, &alt);
+        // // from ERFA "from N" to "from S"
+        // if (az > std::numbers::pi) {
+        //     az -= std::numbers::pi;
+        // } else {
+        //     az += std::numbers::pi;
+        // }
 
-        return;
+        // return;
 
         const auto cos_phi = std::cos(phi), sin_phi = std::sin(phi);
         const auto cos_dec = std::cos(dec), sin_dec = std::sin(dec);
         const auto cos_ha = std::cos(ha), sin_ha = std::sin(ha);
 
         auto x = sin_phi * cos_dec * cos_ha - cos_phi * sin_dec;
-        auto y = -cos_dec * sin_ha;
+        auto y = cos_dec * sin_ha;
         auto z = cos_phi * cos_dec * cos_ha + sin_phi * sin_dec;
 
         auto xx = x * x, yy = y * y;
         decltype(x) r;
         if (xx < yy) {
-            r = yy * sqrt(1.0 + xx / yy);
+            r = std::abs(y) * sqrt(1.0 + xx / yy);
         } else {
-            r = xx * sqrt(1.0 + yy / xx);
+            r = std::abs(x) * sqrt(1.0 + yy / xx);
         }
 
         az = utils::isEqual(r, 0.0) ? 0.0 : std::atan2(y, x);
@@ -697,10 +697,10 @@ protected:
     // AZ, ALT to HA, DEC (AZ from the South through the West)
     void azalt2hadec(double az, double alt, double phi, double& ha, double& dec) const
     {
-        az += std::numbers::pi;
-        eraAe2hd(az, alt, phi, &ha, &dec);
+        // az += std::numbers::pi;
+        // eraAe2hd(az, alt, phi, &ha, &dec);
 
-        return;
+        // return;
 
         const auto cos_phi = std::cos(phi), sin_phi = std::sin(phi);
         const auto cos_az = std::cos(az), sin_az = std::sin(az);
@@ -713,9 +713,9 @@ protected:
         auto xx = x * x, yy = y * y;
         decltype(x) r;
         if (xx < yy) {
-            r = yy * sqrt(1.0 + xx / yy);
+            r = std::abs(y) * sqrt(1.0 + xx / yy);
         } else {
-            r = xx * sqrt(1.0 + yy / xx);
+            r = std::abs(x) * sqrt(1.0 + yy / xx);
         }
 
         ha = utils::isEqual(r, 0.0) ? 0.0 : std::atan2(y, x);
diff --git a/mcc_ser.h b/mcc_ser.h
index 32dac55..1f71a63 100644
--- a/mcc_ser.h
+++ b/mcc_ser.h
@@ -439,8 +439,36 @@ struct MccSerializer<VT> : MccSerializerBase {
         pars.norm_sxgm = true;
         pars.coordpair_format = MccSerializedCoordPairFormat::MCC_SERIALIZED_FORMAT_SXGM_HOURDEG;
 
-        // RA_OBS_MOUNT
+        std::string ra_obs, ra_app, ha, last, ra_app_tg;
+        MccSkyRADEC_OBS r_obs;
+        MccSkyRADEC_APP r_app;
+
+        // quantities in hour representation
         MccSerializerBase::angleFormatFromCoordPairType<VT::pairKind, MccSerializerBase::CO_LON>(pars);
+
+        MccSerializer<MccAngle> ang_sr;
+
+        // RA_OBS_MOUNT
+        auto ccte_err = value.mountPos.toAtSameEpoch(r_obs);
+        if (ccte_err) {
+            return mcc_deduced_err(ccte_err, MccSerializerErrorCode::ERROR_COORD_TRANSFORM);
+        }
+
+        auto err = ang_sr(ra_obs, r_obs, pars);
+        if (err) {
+            return mcc_deduced_err(err, MccSerializerErrorCode::ERROR_UNDERLYING_SERIALIZER);
+        }
+
+        // RA_APP_MOUNT
+        ccte_err = value.mountPos.toAtSameEpoch(r_app);
+        if (ccte_err) {
+            return mcc_deduced_err(ccte_err, MccSerializerErrorCode::ERROR_COORD_TRANSFORM);
+        }
+
+        err = ang_sr(ra_app, r_app, pars);
+        if (err) {
+            return mcc_deduced_err(err, MccSerializerErrorCode::ERROR_UNDERLYING_SERIALIZER);
+        }
     }
 };