diff --git a/.gitmodules b/.gitmodules
index 15f85e4b7912e9d4f18a4b3279f41a0bb653c441..36a336d74aca0a83cd8b7ef6e769040e785f9fea 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -4,3 +4,6 @@
 [submodule "2022-05-06_exciter"]
 	path = 2022-05-06_exciter
 	url = git@git.gsi.de:p.niedermayer/data-analysis-2022-05-06-exciter.git
+[submodule "2022-05-08_btf"]
+	path = 2022-05-08_btf
+	url = git@git.gsi.de:p.niedermayer/data-analysis-2022-05-08-btf.git
diff --git a/2022-05-08_btf b/2022-05-08_btf
new file mode 160000
index 0000000000000000000000000000000000000000..78f902e098183feada87bb5a161bd3dc376de31a
--- /dev/null
+++ b/2022-05-08_btf
@@ -0,0 +1 @@
+Subproject commit 78f902e098183feada87bb5a161bd3dc376de31a