diff --git a/Meade.net.Telescope.UnitTests/TelescopeUnitTests.cs b/Meade.net.Telescope.UnitTests/TelescopeUnitTests.cs
index 9f37054..573c59d 100644
--- a/Meade.net.Telescope.UnitTests/TelescopeUnitTests.cs
+++ b/Meade.net.Telescope.UnitTests/TelescopeUnitTests.cs
@@ -2128,7 +2128,90 @@ namespace Meade.net.Telescope.UnitTests
             _sharedResourcesWrapperMock.Verify(x => x.SendChar(":MS#"), Times.Once);
 
             _utilMock.Verify(x => x.WaitForMilliseconds(It.IsAny<int>()), Times.Exactly(iterations));
+        }
+
+        [Test]
+        public void SlewToAltAzAsync_WhenNotConnected_ThenThrowsException()
+        {
+            _sharedResourcesWrapperMock.Setup(x => x.ProductName).Returns(() => _sharedResourcesWrapperMock.Object.AUTOSTAR497);
+            _sharedResourcesWrapperMock.Setup(x => x.FirmwareVersion).Returns(() => _sharedResourcesWrapperMock.Object.AUTOSTAR497_31EE);
+
+            var exception = Assert.Throws<NotConnectedException>(() => { _telescope.SlewToAltAzAsync(0, 0); });
+            Assert.That(exception.Message, Is.EqualTo("Not connected to telescope when trying to execute: SlewToAltAzAsync"));
+        }
+
+        [Test]
+        public void SlewToAltAzAsync_WhenAltitudeGreaterThan90_ThenThrowsException()
+        {
+            _sharedResourcesWrapperMock.Setup(x => x.ProductName).Returns(() => _sharedResourcesWrapperMock.Object.AUTOSTAR497);
+            _sharedResourcesWrapperMock.Setup(x => x.FirmwareVersion).Returns(() => _sharedResourcesWrapperMock.Object.AUTOSTAR497_31EE);
+            _telescope.Connected = true;
+
+            var exception = Assert.Throws<InvalidValueException>(() => { _telescope.SlewToAltAzAsync(0, 90.1); });
+            Assert.That(exception.Message, Is.EqualTo("Altitude cannot be greater than 90."));
+        }
+
+        [Test]
+        public void SlewToAltAzAsync_WhenAltitudeLowerThan0_ThenThrowsException()
+        {
+            _sharedResourcesWrapperMock.Setup(x => x.ProductName).Returns(() => _sharedResourcesWrapperMock.Object.AUTOSTAR497);
+            _sharedResourcesWrapperMock.Setup(x => x.FirmwareVersion).Returns(() => _sharedResourcesWrapperMock.Object.AUTOSTAR497_31EE);
+            _telescope.Connected = true;
+
+            var exception = Assert.Throws<InvalidValueException>(() => { _telescope.SlewToAltAzAsync(0, -0.1); });
+            Assert.That(exception.Message, Is.EqualTo("Altitide cannot be less than 0."));
+        }
+
+        [Test]
+        public void SlewToAltAzAsync_WhenAzimuth360OrHigher_ThenThrowsException()
+        {
+            _sharedResourcesWrapperMock.Setup(x => x.ProductName).Returns(() => _sharedResourcesWrapperMock.Object.AUTOSTAR497);
+            _sharedResourcesWrapperMock.Setup(x => x.FirmwareVersion).Returns(() => _sharedResourcesWrapperMock.Object.AUTOSTAR497_31EE);
+            _telescope.Connected = true;
+
+            var exception = Assert.Throws<InvalidValueException>(() => { _telescope.SlewToAltAzAsync(360, 0); });
+            Assert.That(exception.Message, Is.EqualTo("Azimuth cannot be 360 or higher."));
+        }
+
+        [Test]
+        public void SlewToAltAzAsync_WhenAzimuthLowerThan0_ThenThrowsException()
+        {
+            _sharedResourcesWrapperMock.Setup(x => x.ProductName).Returns(() => _sharedResourcesWrapperMock.Object.AUTOSTAR497);
+            _sharedResourcesWrapperMock.Setup(x => x.FirmwareVersion).Returns(() => _sharedResourcesWrapperMock.Object.AUTOSTAR497_31EE);
+            _telescope.Connected = true;
+
+            var exception = Assert.Throws<InvalidValueException>(() => { _telescope.SlewToAltAzAsync(-0.1, 0); });
+            Assert.That(exception.Message, Is.EqualTo("Azimuth cannot be less than 0."));
+        }
+
+        [Test]
+        public void SlewToAltAzAsync_WhenAltAndAzValid_ThenConvertsToRADec()
+        {
+
+            var altitude = 30;
+            var azimuth = 45;
+            var rightAscension = 20;
+            var declination = 10;
+
+            _sharedResourcesWrapperMock.Setup(x => x.ProductName).Returns(() => _sharedResourcesWrapperMock.Object.AUTOSTAR497);
+            _sharedResourcesWrapperMock.Setup(x => x.FirmwareVersion).Returns(() => _sharedResourcesWrapperMock.Object.AUTOSTAR497_31EE);
+            _telescope.Connected = true;
+
+            _sharedResourcesWrapperMock.Setup(x => x.SendString(":GC#")).Returns("10/15/20");
+            _sharedResourcesWrapperMock.Setup(x => x.SendString(":GL#")).Returns("20:15:10");
+            _sharedResourcesWrapperMock.Setup(x => x.SendString(":GG#")).Returns("-1.0");
+
+            _astroMathsMock
+                .Setup(x => x.ConvertHozToEq(It.IsAny<DateTime>(), It.IsAny<double>(), It.IsAny<double>(),
+                    It.IsAny<HorizonCoordinates>())).Returns(new EquatorialCoordinates(){ Declination = declination, RightAscension = rightAscension });
+
+            _sharedResourcesWrapperMock.Setup(x => x.SendChar(":MS#")).Returns("0");
+
+            _telescope.SlewToAltAzAsync(azimuth, altitude);
             
+            Assert.That(_telescope.TargetRightAscension, Is.EqualTo(rightAscension));
+            Assert.That(_telescope.TargetDeclination, Is.EqualTo(declination));
+            _sharedResourcesWrapperMock.Verify(x => x.SendChar(":MS#"), Times.Once);
         }
     }
 }
diff --git a/Meade.net.Telescope/Telescope.cs b/Meade.net.Telescope/Telescope.cs
index 9d82148..a95943e 100644
--- a/Meade.net.Telescope/Telescope.cs
+++ b/Meade.net.Telescope/Telescope.cs
@@ -1395,6 +1395,8 @@ namespace ASCOM.Meade.net
 
         public void SlewToAltAzAsync(double azimuth, double altitude)
         {
+            CheckConnected("SlewToAltAzAsync");
+
             if (altitude > 90)
                 throw new ASCOM.InvalidValueException("Altitude cannot be greater than 90.");
 
@@ -1408,8 +1410,7 @@ namespace ASCOM.Meade.net
                 throw new ASCOM.InvalidValueException("Azimuth cannot be less than 0.");
 
             LogMessage("SlewToAltAzAsync", $"Az={azimuth} Alt={altitude}");
-            CheckConnected("SlewToAltAzAsync");
-
+            
             HorizonCoordinates altAz = new HorizonCoordinates();
             altAz.Azimuth = azimuth;
             altAz.Altitude = altitude;