diff --git a/src/python_opensky/opensky.py b/src/python_opensky/opensky.py
index 2e539a5..089d402 100644
--- a/src/python_opensky/opensky.py
+++ b/src/python_opensky/opensky.py
@@ -37,15 +37,35 @@ class OpenSky:
     _auth: BasicAuth | None = None
     _contributing_user: bool = False
 
-    def authenticate(self, auth: BasicAuth, *, contributing_user: bool = False) -> None:
+    async def authenticate(
+        self,
+        auth: BasicAuth,
+        *,
+        contributing_user: bool = False,
+    ) -> None:
         """Authenticate the user."""
         self._auth = auth
+        try:
+            await self.get_states()
+        except OpenSkyUnauthenticatedError as exc:
+            self._auth = None
+            raise OpenSkyUnauthenticatedError from exc
         self._contributing_user = contributing_user
         if contributing_user:
             self.opensky_credits = 8000
         else:
             self.opensky_credits = 4000
 
+    @property
+    def is_contributing_user(self) -> bool:
+        """Return if the user is contributing to OpenSky."""
+        return self._contributing_user
+
+    @property
+    def is_authenticated(self) -> bool:
+        """Return if the user is correctly authenticated."""
+        return self._auth is not None
+
     async def _request(
         self,
         uri: str,
@@ -107,6 +127,8 @@ async def _request(
             ClientResponseError,
             socket.gaierror,
         ) as exception:
+            if isinstance(exception, ClientResponseError) and exception.status == 401:
+                raise OpenSkyUnauthenticatedError from exception
             msg = "Error occurred while communicating with OpenSky API"
             raise OpenSkyConnectionError(msg) from exception
 
diff --git a/tests/test_states.py b/tests/test_states.py
index 8ac121e..1d48941 100644
--- a/tests/test_states.py
+++ b/tests/test_states.py
@@ -91,6 +91,16 @@ async def test_own_states(
     aresponses: ResponsesMockServer,
 ) -> None:
     """Test retrieving own states."""
+    aresponses.add(
+        OPENSKY_URL,
+        "/api/states/all",
+        "GET",
+        aresponses.Response(
+            status=200,
+            headers={"Content-Type": "application/json"},
+            text=load_fixture("states.json"),
+        ),
+    )
     aresponses.add(
         OPENSKY_URL,
         "/api/states/own",
@@ -103,10 +113,14 @@ async def test_own_states(
     )
     async with aiohttp.ClientSession() as session:
         opensky = OpenSky(session=session)
-        opensky.authenticate(BasicAuth(login="test", password="test"))
+        await opensky.authenticate(
+            BasicAuth(login="test", password="test"),
+            contributing_user=True,
+        )
         response: StatesResponse = await opensky.get_own_states()
         assert len(response.states) == 4
-        assert opensky.remaining_credits() == opensky.opensky_credits
+        assert opensky.opensky_credits == 8000
+        assert opensky.remaining_credits() == 7996
         await opensky.close()
 
 
@@ -114,6 +128,16 @@ async def test_unavailable_own_states(
     aresponses: ResponsesMockServer,
 ) -> None:
     """Test retrieving no own states."""
+    aresponses.add(
+        OPENSKY_URL,
+        "/api/states/all",
+        "GET",
+        aresponses.Response(
+            status=200,
+            headers={"Content-Type": "application/json"},
+            text=load_fixture("states.json"),
+        ),
+    )
     aresponses.add(
         OPENSKY_URL,
         "/api/states/own",
@@ -126,7 +150,10 @@ async def test_unavailable_own_states(
     )
     async with aiohttp.ClientSession() as session:
         opensky = OpenSky(session=session)
-        opensky.authenticate(BasicAuth(login="test", password="test"))
+        await opensky.authenticate(
+            BasicAuth(login="test", password="test"),
+            contributing_user=True,
+        )
         response: StatesResponse = await opensky.get_own_states()
         assert response.states is not None
         assert len(response.states) == 0
@@ -244,27 +271,64 @@ def response_handler(request: BaseRequest) -> Response:
         "/api/states/all",
         "GET",
         response_handler,
+        repeat=2,
     )
 
     async with aiohttp.ClientSession() as session:
         opensky = OpenSky(session=session)
-        opensky.authenticate(BasicAuth(login="test", password="test"))
+        await opensky.authenticate(BasicAuth(login="test", password="test"))
         await opensky.get_states()
         await opensky.close()
 
 
-async def test_user_credits() -> None:
+async def test_unauthorized(aresponses: ResponsesMockServer) -> None:
+    """Test request authentication."""
+    aresponses.add(
+        OPENSKY_URL,
+        "/api/states/all",
+        "GET",
+        aresponses.Response(
+            status=401,
+            headers={"Content-Type": "application/json"},
+            text=load_fixture("states.json"),
+        ),
+    )
+
+    async with aiohttp.ClientSession() as session:
+        opensky = OpenSky(session=session)
+        try:
+            await opensky.authenticate(BasicAuth(login="test", password="test"))
+            pytest.fail("Should've thrown exception")
+        except OpenSkyUnauthenticatedError:
+            pass
+        assert opensky.is_authenticated is False
+        await opensky.close()
+
+
+async def test_user_credits(aresponses: ResponsesMockServer) -> None:
     """Test authenticated user credits."""
+    aresponses.add(
+        OPENSKY_URL,
+        "/api/states/all",
+        "GET",
+        aresponses.Response(
+            status=200,
+            headers={"Content-Type": "application/json"},
+            text=load_fixture("states.json"),
+        ),
+        repeat=2,
+    )
     async with aiohttp.ClientSession() as session:
         opensky = OpenSky(session=session)
         assert opensky.opensky_credits == 400
-        opensky.authenticate(BasicAuth(login="test", password="test"))
+        await opensky.authenticate(BasicAuth(login="test", password="test"))
         assert opensky.opensky_credits == 4000
-        opensky.authenticate(
+        await opensky.authenticate(
             BasicAuth(login="test", password="test"),
             contributing_user=True,
         )
         assert opensky.opensky_credits == 8000
+        assert opensky.is_contributing_user is True
         await opensky.close()