Index: trunk/MagicSoft/Cosy/catalog/SlaStars.cc
===================================================================
--- trunk/MagicSoft/Cosy/catalog/SlaStars.cc	(revision 1274)
+++ trunk/MagicSoft/Cosy/catalog/SlaStars.cc	(revision 1275)
@@ -40,5 +40,5 @@
     slaMappa(2000.0, mjd, fAmprms);
     slaAoppa(mjd, 0,                    // mjd, UT1-UTC
-             GetElong(), GetPhi(), 148, // g”ttingen long, lat, height
+             GetElong(), GetPhi(), 148, // göttingen long, lat, height
              0, 0,                      // polar motion x, y-coordinate (radians)
              273.155, 1013.25, 0.5,     // temp, pressure, humidity
@@ -69,4 +69,61 @@
 
     return RaDec(ra, dec);
+}
+
+RaDec SlaStars::CalcRaDecFast(const AltAz &altaz) const
+{
+    //
+    // This function does a coordinate system transformation only.
+    // This is very fast compared to a correct tranformation with all
+    // effects, but much less accurate.
+    //
+    // It transforms Altitude/Azimuth [rad] into
+    // Right Ascension/Declination [rad] 
+    //
+    double ha, dec;
+    slaDh2e(altaz.Az(), altaz.Alt(), GetPhi(), &ha, &dec);
+    return RaDec(GetAlpha()-ha, dec);
+}
+
+RaDec SlaStars::CalcRaDecFast(const ZdAz &zdaz) const
+{
+    //
+    // This function does a coordinate system transformation only.
+    // This is very fast compared to a correct tranformation with all
+    // effects, but much less accurate.
+    //
+    // It transforms Zenith Distance/Azimuth [rad] into
+    // Right Ascension/Declination [rad] 
+    //
+    return CalcRaDecFast(AltAz(kPiDiv2-zdaz.Zd(), zdaz.Az()));
+}
+
+ZdAz SlaStars::CalcZdAzFast(const RaDec &radec) const
+{
+    //
+    // This function does a coordinate system transformation only.
+    // This is very fast compared to a correct tranformation with all
+    // effects, but much less accurate.
+    //
+    // It transforms Right Ascension/Declination [rad] into
+    // zenith Distance/Azimuth [rad]
+    //
+    AltAz altaz = CalcAltAzFast(radec);
+    return ZdAz(kPiDiv2-altaz.Alt(), altaz.Az());
+}
+
+AltAz SlaStars::CalcAltAzFast(const RaDec &radec) const
+{
+    //
+    // This function does a coordinate system transformation only.
+    // This is very fast compared to a correct tranformation with all
+    // effects, but much less accurate.
+    //
+    // It transforms Right Ascension/Declination [rad] into
+    // Altitude/Azimuth [rad]
+    //
+    double az, el;
+    slaDe2h(GetAlpha()-radec.Ra(), radec.Dec(), GetPhi(), &az, &el);
+    return AltAz(el, az);
 }