diff --git a/docs/CPU_DATA_ANALYSIS_REFINEMENT.md b/docs/CPU_DATA_ANALYSIS_REFINEMENT.md
index 830f3aec5..b136b6ed0 100644
--- a/docs/CPU_DATA_ANALYSIS_REFINEMENT.md
+++ b/docs/CPU_DATA_ANALYSIS_REFINEMENT.md
@@ -356,7 +356,8 @@ The refined model's map coefficients, `<prefix>_refined_maps.mtz`, are $2mF_o -
 $\sigma_A$ of §14.4, so the maps carry the weights the target was minimised with; $m$ is
 $I_1(X)/I_0(X)$, $X = 2F_oD|F_\mathrm{model}|/\Sigma$, for an acentric reflection and $\tanh(X/2)$ for a
 centric one. Where the merge kept the Bijvoet pairs, the anomalous difference map is made on the refined
-model's phases too, and read by the blob finder below.
+model's phases too, written in the same file as `ANOM`/`PHANOM` (as in `<prefix>_maps.mtz`; missing where a
+reflection has no Bijvoet pair), and read by the blob finder below.
 
 ### 15.9 Unexplained density: blobs
 
diff --git a/docs/RUGNUX_MODEL_AND_REFERENCE.md b/docs/RUGNUX_MODEL_AND_REFERENCE.md
index cde751bfe..c67389d9b 100644
--- a/docs/RUGNUX_MODEL_AND_REFERENCE.md
+++ b/docs/RUGNUX_MODEL_AND_REFERENCE.md
@@ -440,7 +440,7 @@ the data, a weak shell says nothing about them, and nothing acts on it.
 |---|---|---|
 | `<prefix>.mtz` / `.cif` / `.hkl` | The answer: the data's space group, with only the class-(b) labels from the model | Refinement, deposition, everything by default |
 | `<prefix>_model.cif` / `.pdb`, `<prefix>_maps.mtz` | The model as placed, in the frame of `<prefix>.mtz`, and its map coefficients (Coot/PyMOL open them as maps) | Starting refinement (REFMAC5, phenix.refine), PanDDA, Coot |
-| `<prefix>_refined_model.cif`/`.pdb`, `<prefix>_refined_maps.mtz`, `<prefix>_blobs.json` | The placed model refined by rugnux, its map coefficients, and the unexplained blobs of its difference map | A first look at the refined density and at what the model leaves unexplained; continuing refinement |
+| `<prefix>_refined_model.cif`/`.pdb`, `<prefix>_refined_maps.mtz`, `<prefix>_blobs.json` | The placed model refined by rugnux, its map coefficients (with the anomalous difference map's, `ANOM`/`PHANOM`, where the merge kept the Bijvoet pairs, as in `<prefix>_maps.mtz`), and the unexplained blobs of its difference map | A first look at the refined density and at what the model leaves unexplained; continuing refinement |
 | `<prefix>_twin_<SG>.mtz` / `.cif` | The same data merged in a subgroup with a twin law — written from the data, model or not | Twin refinement, where you suspect the higher group absorbed a twin law |
 | `<prefix>_mr.mtz` / `.cif`, `<prefix>_mr_model.pdb` / `.cif`, `<prefix>_mr_*` maps | The merge in the space group the model chose (`MODEL_CHOICE_SPACE_GROUP=`), and the model placed there | Refinement *if* you accept the model's choice; compare R-free against the answer's |
 
diff --git a/image_analysis/structure_refinement/Refinement.cpp b/image_analysis/structure_refinement/Refinement.cpp
index 4c31dc9b4..e2449d33a 100644
--- a/image_analysis/structure_refinement/Refinement.cpp
+++ b/image_analysis/structure_refinement/Refinement.cpp
@@ -8,6 +8,7 @@
 #include <chrono>
 #include <set>
 #include <future>
+#include <limits>
 #include <map>
 #include <optional>
 #include <cmath>
@@ -1252,12 +1253,25 @@ void MakeMaps(Context &ctx, const std::vector<MergedReflection> &merged, double
         gemmi::AsuData<std::complex<float>> anom;
         anom.unit_cell_ = ctx.cell;
         anom.spacegroup_ = ctx.sg;
+        // Its coefficients in the maps file too (ANOM/PHANOM, as model validation writes them), missing (NaN) where
+        // the reflection has no Bijvoet pair.
+        const float nan = std::numeric_limits<float>::quiet_NaN();
+        MtzTable::Column anom_col{"ANOM", 'F', 1, {}}, phanom_col{"PHANOM", 'P', 1, {}};
         for (size_t m = 0; m < ctx.refl.Size(); m++) {
             const auto it = danom.find(ctx.refl.hkl[m]);
-            if (it != danom.end())
-                anom.v.push_back({ctx.refl.hkl[m], it->second * std::polar(1.0f, static_cast<float>(std::arg(fmodel[m]) - PI / 2))});
+            if (it == danom.end()) {
+                anom_col.values.push_back(nan);
+                phanom_col.values.push_back(nan);
+                continue;
+            }
+            const std::complex<float> c = it->second * std::polar(1.0f, static_cast<float>(std::arg(fmodel[m]) - PI / 2));
+            anom.v.push_back({ctx.refl.hkl[m], c});
+            anom_col.values.push_back(std::abs(c));
+            phanom_col.values.push_back(MtzPhase(std::arg(c) * 180.0 / PI));
         }
         if (!anom.v.empty()) {
+            mtz.columns.push_back(std::move(anom_col));
+            mtz.columns.push_back(std::move(phanom_col));
             result.anomalous_map = std::make_shared<gemmi::Grid<float>>(
                 MapFromFPhi(gemmi::get_f_phi_on_grid<float>(anom, gemmi::get_size_for_hkl(anom, {{0, 0, 0}}, 3.0), true)));
             result.anomalous_map_rms = gemmi::calculate_data_statistics(result.anomalous_map->data).rms;