diff --git a/daskms/experimental/katdal/corr_products.py b/daskms/experimental/katdal/corr_products.py
index 85f1547f..ea4674a6 100644
--- a/daskms/experimental/katdal/corr_products.py
+++ b/daskms/experimental/katdal/corr_products.py
@@ -1,3 +1,24 @@
+# Creation of the correlation product index is derived from
+# https://github.com/ska-sa/katdal/blob/v0.22/scripts/mvftoms.py
+# under the following license
+#
+# ################################################################################
+# Copyright (c) 2011-2023, National Research Foundation (SARAO)
+#
+# Licensed under the BSD 3-Clause License (the "License"); you may not use
+# this file except in compliance with the License. You may obtain a copy
+# of the License at
+#
+#   https://opensource.org/licenses/BSD-3-Clause
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+################################################################################
+
+
 from collections import namedtuple
 
 import numpy as np
diff --git a/daskms/experimental/katdal/msv2_facade.py b/daskms/experimental/katdal/msv2_facade.py
index 7dc2b676..559288fd 100644
--- a/daskms/experimental/katdal/msv2_facade.py
+++ b/daskms/experimental/katdal/msv2_facade.py
@@ -1,3 +1,23 @@
+# Much of the subtable generation code is derived from
+# https://github.com/ska-sa/katdal/blob/v0.22/katdal/ms_extra.py
+# under the following license
+#
+# ################################################################################
+# Copyright (c) 2011-2023, National Research Foundation (SARAO)
+#
+# Licensed under the BSD 3-Clause License (the "License"); you may not use
+# this file except in compliance with the License. You may obtain a copy
+# of the License at
+#
+#   https://opensource.org/licenses/BSD-3-Clause
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+################################################################################
+
 from functools import partial
 
 import dask.array as da
diff --git a/daskms/experimental/katdal/transpose.py b/daskms/experimental/katdal/transpose.py
index a19fdace..068a13c4 100644
--- a/daskms/experimental/katdal/transpose.py
+++ b/daskms/experimental/katdal/transpose.py
@@ -1,3 +1,24 @@
+# The numba transposition code is derived from
+# https://github.com/ska-sa/katdal/blob/v0.22/scripts/mvftoms.py
+# under the following license
+#
+# ################################################################################
+# Copyright (c) 2011-2023, National Research Foundation (SARAO)
+#
+# Licensed under the BSD 3-Clause License (the "License"); you may not use
+# this file except in compliance with the License. You may obtain a copy
+# of the License at
+#
+#   https://opensource.org/licenses/BSD-3-Clause
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+################################################################################
+
+
 import dask.array as da
 import numpy as np
 
diff --git a/daskms/experimental/katdal/uvw.py b/daskms/experimental/katdal/uvw.py
index 12e3425a..21e8e4ea 100644
--- a/daskms/experimental/katdal/uvw.py
+++ b/daskms/experimental/katdal/uvw.py
@@ -1,3 +1,24 @@
+# The uvw calculation code is derived from
+# https://github.com/ska-sa/katdal/blob/v0.22/katdal/ms_async.py
+# under the following license
+#
+# ################################################################################
+# Copyright (c) 2011-2023, National Research Foundation (SARAO)
+#
+# Licensed under the BSD 3-Clause License (the "License"); you may not use
+# this file except in compliance with the License. You may obtain a copy
+# of the License at
+#
+#   https://opensource.org/licenses/BSD-3-Clause
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+################################################################################
+
+
 import dask.array as da
 from katpoint import Target
 import numpy as np