diff --git a/python/lsst/daf/butler/registry/obscore/_config.py b/python/lsst/daf/butler/registry/obscore/_config.py
index 928c7132d7..e7f454d716 100644
--- a/python/lsst/daf/butler/registry/obscore/_config.py
+++ b/python/lsst/daf/butler/registry/obscore/_config.py
@@ -116,7 +116,7 @@ class SpatialPluginConfig(pydantic.BaseModel):
     cls: str
     """Name of the class implementing plugin methods."""
 
-    config: dict[str, Any] = {}
+    config: dict[str, Any] = pydantic.Field(default_factory=dict)
     """Configuration object passed to plugin ``initialize()`` method."""
 
 
@@ -144,7 +144,13 @@ class ObsCoreConfig(pydantic.BaseModel):
     """
 
     facility_name: str
-    """Value for the ``facility_name`` column."""
+    """Default value for the ``facility_name`` column. If an instrument
+    is listed in ``facility_map`` that will be used in preference but this
+    value must always be set as a fallback."""
+
+    facility_map: dict[str, str] = pydantic.Field(default_factory=dict)
+    """Mapping of instrument name to facility name. Takes precedence over
+    the ``facility_name``."""
 
     extra_columns: None | (
         dict[str, StrictFloat | StrictInt | StrictBool | StrictStr | ExtraColumnConfig]
diff --git a/python/lsst/daf/butler/registry/obscore/_records.py b/python/lsst/daf/butler/registry/obscore/_records.py
index e4c0ab1905..bbd29bfadf 100644
--- a/python/lsst/daf/butler/registry/obscore/_records.py
+++ b/python/lsst/daf/butler/registry/obscore/_records.py
@@ -163,7 +163,6 @@ def __call__(self, ref: DatasetRef) -> Record | None:
         record["dataproduct_type"] = dataset_config.dataproduct_type
         record["dataproduct_subtype"] = dataset_config.dataproduct_subtype
         record["o_ucd"] = dataset_config.o_ucd
-        record["facility_name"] = self.config.facility_name
         record["calib_level"] = dataset_config.calib_level
         if dataset_config.obs_collection is not None:
             record["obs_collection"] = dataset_config.obs_collection
@@ -171,10 +170,13 @@ def __call__(self, ref: DatasetRef) -> Record | None:
             record["obs_collection"] = self.config.obs_collection
         record["access_format"] = dataset_config.access_format
 
-        record["instrument_name"] = dataId.get("instrument")
+        instrument_name = cast(str, dataId.get("instrument"))
+        record["instrument_name"] = instrument_name
         if self.schema.dataset_fk is not None:
             record[self.schema.dataset_fk.name] = ref.id
 
+        record["facility_name"] = self.config.facility_map.get(instrument_name, self.config.facility_name)
+
         timespan = dataId.timespan
         if timespan is not None:
             if timespan.begin is not None:
diff --git a/tests/config/basic/obscore.yaml b/tests/config/basic/obscore.yaml
index 966f8a9cbf..5cbdcd26b9 100644
--- a/tests/config/basic/obscore.yaml
+++ b/tests/config/basic/obscore.yaml
@@ -3,6 +3,8 @@ version: 0
 table_name: obscore
 collection_type: RUN
 facility_name: daf_butler_test
+facility_map:
+  DummyCam: derived_facility
 obs_collection: daf_butler_obs_collection
 collections: []
 use_butler_uri: false
diff --git a/tests/test_obscore.py b/tests/test_obscore.py
index e9bb88d610..830282cc00 100644
--- a/tests/test_obscore.py
+++ b/tests/test_obscore.py
@@ -479,7 +479,7 @@ def test_update_exposure_region(self) -> None:
         )
         self.assertEqual(count, 2)
 
-        with obscore.query(["s_ra", "s_dec", "s_region", "lsst_detector"]) as result:
+        with obscore.query(["s_ra", "s_dec", "s_region", "lsst_detector", "facility_name"]) as result:
             rows = list(result)
             self.assertEqual(len(rows), 4)
             for row in rows:
@@ -491,6 +491,7 @@ def test_update_exposure_region(self) -> None:
                     self.assertIsNone(row.s_ra)
                     self.assertIsNone(row.s_dec)
                     self.assertIsNone(row.s_region)
+                self.assertEqual(row.facility_name, "derived_facility")
 
 
 class SQLiteObsCoreTest(ObsCoreTests, unittest.TestCase):