From b35383ff3ea8f4c5127c6de7c7ef98daaf3d0fc0 Mon Sep 17 00:00:00 2001
From: Cail Daley <cail.daley@cea.fr>
Date: Sun, 25 Oct 2026 23:08:56 +0100
Subject: [PATCH] Exclude star halos from default mask cut

---
 config/calibration/mask_v2.0.yaml             | 24 ++++++-------------
 src/sp_validation/galaxy.py                   | 14 +++++------
 .../tests/test_campaign_readers.py            |  6 +++++
 3 files changed, 19 insertions(+), 25 deletions(-)

diff --git a/config/calibration/mask_v2.0.yaml b/config/calibration/mask_v2.0.yaml
index 930ae42fc..cb89336b8 100644
--- a/config/calibration/mask_v2.0.yaml
+++ b/config/calibration/mask_v2.0.yaml
@@ -4,7 +4,7 @@
 # mask columns MASK_<bit>_<label>, where True means MASKED. They are therefore
 # cut with `kind: equal, value: False` (keep the un-masked objects):
 #
-# Reason bits of the ShapePipe r-band default bitmask:
+# ShapePipe mask reason bits:
 #
 #   MASK_1_Faint_star_halos     faint star halos (bit 0; value 1)
 #   MASK_2_Bright_star_halos    bright star halos (bit 1; value 2)
@@ -19,12 +19,11 @@
 #                               u, g, r, i, HSC z-band coverage
 #   MASK_2048_z2                no Pan-STARRS z-band (z2) coverage
 #
-# The default selection (see sp_validation.galaxy.DEFAULT_MASK_COLUMNS) is
-# bits 1 + 2 + 4 + 8 + 64 + 1024, whose OR matches mask_r, the r-band
-# mask, on covered granules (verified on the P3 sky area); footprint-edge
-# granules without mask_r coverage can differ. The other coverage flags and bit 2048 are listed
-# here but commented out, since ORing all of them masks essentially
-# everything.
+# The default external-mask cut (see sp_validation.galaxy.DEFAULT_MASK_COLUMNS)
+# uses bits 4 + 8 + 64 + 1024: star bodies, manual masks, r-band coverage and
+# MaxiMask. It excludes star-halo bits 1 and 2. Other coverage flags and bit
+# 2048 are listed here but commented out, since ORing all of them masks
+# essentially everything.
 
 # General parameters (can also given on command line)
 params:
@@ -55,15 +54,6 @@ dat:
     label: "star bodies"
     kind: equal
     value: False
-  # Star-halo bits follow the UNIONS mask producer schema.
-  - col_name: MASK_1_Faint_star_halos
-    label: "faint star halos"
-    kind: equal
-    value: False
-  - col_name: MASK_2_Bright_star_halos
-    label: "bright star halos"
-    kind: equal
-    value: False
   - col_name: MASK_8_Manual
     label: "manual mask"
     kind: equal
@@ -73,7 +63,7 @@ dat:
     kind: equal
     value: False
 
-  # r-band coverage. Required for the OR above to reproduce mask_r.
+  # r-band coverage.
   - col_name: MASK_64_r
     label: "r-band imaging"
     kind: equal
diff --git a/src/sp_validation/galaxy.py b/src/sp_validation/galaxy.py
index 57f3f14b5..de276ec5f 100644
--- a/src/sp_validation/galaxy.py
+++ b/src/sp_validation/galaxy.py
@@ -35,23 +35,21 @@
 #: not write bit 512). Post-processed v1 comprehensive catalogues carry the same
 #: columns, presented under these names by ``sp_validation.grammar``.
 #:
-#: The r-band default bitmask uses bits 1 (faint star halos), 2 (bright star
-#: halos), 4 (star bodies), 8 (manual galaxy mask), 64 (r-band coverage) and
-#: 1024 (MaxiMask). The per-band coverage flags are 16 (u), 32 (g), 64 (r),
+#: The default external-mask cut uses bits 4 (star bodies), 8 (manual galaxy
+#: mask), 64 (r-band coverage) and 1024 (MaxiMask); star-halo bits 1 and 2 are
+#: deliberately excluded. The per-band coverage flags are 16 (u), 32 (g), 64 (r),
 #: 128 (i) and 256 (HSC z); 2048 is ``True`` where Pan-STARRS z-band (z2)
 #: coverage is absent.
 MASK_COLUMNS = tuple(
     mask_column(bit) for bit in (1, 2, 4, 8, 16, 32, 64, 128, 256, 1024, 2048)
 )
 
-#: Mask columns OR'd together for the default galaxy selection. This set is
-#: the ShapePipe r-band default bitmask: their OR matches ``mask_r`` on covered
-#: granules (verified on the P3 sky area), with differences at footprint edges
-#: without map coverage.
+#: Mask columns OR'd together for the default galaxy selection: star bodies,
+#: manual masks, r-band coverage and MaxiMask. Star-halo bits are excluded.
 #: Deliberately not a blanket OR over MASK_COLUMNS: the other coverage flags
 #: (bits 16, 32, 128, 256) and bit 2048 would mask essentially the whole
 #: catalogue.
-DEFAULT_MASK_COLUMNS = tuple(mask_column(bit) for bit in (4, 1, 2, 8, 64, 1024))
+DEFAULT_MASK_COLUMNS = tuple(mask_column(bit) for bit in (4, 8, 64, 1024))
 
 
 def _column_names(dd):
diff --git a/src/sp_validation/tests/test_campaign_readers.py b/src/sp_validation/tests/test_campaign_readers.py
index ccaa7f228..e6deb93da 100644
--- a/src/sp_validation/tests/test_campaign_readers.py
+++ b/src/sp_validation/tests/test_campaign_readers.py
@@ -337,6 +337,12 @@ def setUp(self):
         self._dat = make_galaxy_data(5)
 
     def test_default_columns(self):
+        self.assertEqual(
+            galaxy.DEFAULT_MASK_COLUMNS,
+            ("MASK_4_Stars", "MASK_8_Manual", "MASK_64_r", "MASK_1024_Maximask"),
+        )
+        self.assertNotIn("MASK_1_Faint_star_halos", galaxy.DEFAULT_MASK_COLUMNS)
+        self.assertNotIn("MASK_2_Bright_star_halos", galaxy.DEFAULT_MASK_COLUMNS)
         self._dat["MASK_4_Stars"][0] = True
         self._dat["MASK_1024_Maximask"][3] = True