diff --git a/.gitignore b/.gitignore
index b91a2b1..3be7554 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,5 @@
 # vendor / large data — never commit
-data/
+/data/
 refs/
 _phase0_archive/
 *.idat
diff --git a/src/simurg/cn/data/cytoBand_GRCh37.txt.gz b/src/simurg/cn/data/cytoBand_GRCh37.txt.gz
new file mode 100644
index 0000000..ee9ab76
Binary files /dev/null and b/src/simurg/cn/data/cytoBand_GRCh37.txt.gz differ
diff --git a/src/simurg/cn/data/cytoBand_GRCh38.txt.gz b/src/simurg/cn/data/cytoBand_GRCh38.txt.gz
new file mode 100644
index 0000000..691edde
Binary files /dev/null and b/src/simurg/cn/data/cytoBand_GRCh38.txt.gz differ
diff --git a/src/simurg/cn/data/mask_GRCh37.bed b/src/simurg/cn/data/mask_GRCh37.bed
new file mode 100644
index 0000000..3504346
--- /dev/null
+++ b/src/simurg/cn/data/mask_GRCh37.bed
@@ -0,0 +1,26 @@
+# centromeres, gvar/stalk bands, acrocentric p-arms; derived from UCSC hg19 cytoBand
+1	121500000	142600000
+2	90500000	96800000
+3	87900000	98300000
+4	48200000	52700000
+5	46100000	50700000
+6	58700000	63300000
+7	58000000	61700000
+8	43100000	48100000
+9	47300000	65900000
+10	38000000	42300000
+11	51600000	55700000
+12	33300000	38200000
+13	0	19500000
+14	0	19100000
+15	0	20700000
+16	34600000	47000000
+17	22200000	25800000
+18	15400000	19000000
+19	20000000	32400000
+20	25600000	29400000
+21	0	14300000
+22	0	17900000
+X	58100000	63000000
+Y	11600000	13400000
+Y	28800000	59373566
diff --git a/src/simurg/cn/data/mask_GRCh38.bed b/src/simurg/cn/data/mask_GRCh38.bed
new file mode 100644
index 0000000..db1af68
--- /dev/null
+++ b/src/simurg/cn/data/mask_GRCh38.bed
@@ -0,0 +1,26 @@
+# centromeres, gvar/stalk bands, acrocentric p-arms; derived from UCSC hg38 cytoBand
+1	121700000	143200000
+2	91800000	96000000
+3	87800000	98600000
+4	48200000	51800000
+5	46100000	51400000
+6	58500000	62600000
+7	58100000	62100000
+8	43200000	47200000
+9	42200000	61500000
+10	38000000	41600000
+11	51000000	55800000
+12	33200000	37800000
+13	0	18900000
+14	0	18200000
+15	0	20500000
+16	35300000	47000000
+17	22700000	27400000
+18	15400000	21500000
+19	19900000	31900000
+20	25700000	30400000
+21	0	13000000
+22	0	17400000
+X	58100000	63800000
+Y	10300000	10600000
+Y	26600000	57227415