diff --git a/METIS/METIS_WCU.yaml b/METIS/METIS_WCU.yaml
new file mode 100644
index 00000000..f3d813c7
--- /dev/null
+++ b/METIS/METIS_WCU.yaml
@@ -0,0 +1,26 @@
+---
+### METIS WCU MODE
+
+object: instrument
+alias: INST
+name: wcu
+description: warm calibration unit mode
+date_modified: 2024-04-06
+changes:
+  - 2024-04-06 (FH) created file
+
+properties:
+
+effects: []
+
+---
+### default simulation parameters needed for a METIS simulation
+object: simulation
+alias: SIM
+name: METIS_simulation_parameters
+description: RC simulation parameters which need to change for a METIS run
+
+properties:
+  spectral:
+    spectral_bin_width: !!float 1E-3   # microns, defines fov wavelengths
+    spectral_resolution: 5000          # defines skycalc resolution
diff --git a/METIS/default.yaml b/METIS/default.yaml
index 25ec32c4..47b2d3da 100644
--- a/METIS/default.yaml
+++ b/METIS/default.yaml
@@ -5,7 +5,7 @@ object: configuration
 alias: OBS
 name: METIS_default_configuration
 description: default parameters needed for a METIS simulation
-date_modified: 2022-03-14
+date_modified: 2024-04-03
 changes:
   - 2021-12-16 (OC) chopnod defaults to perpendicular
   - 2021-12-16 (OC) default slits renamed
@@ -15,6 +15,7 @@ changes:
   - 2022-02-20 (OC) pupil_transmission now an OBS parameter
   - 2022-02-21 (OC) linear interpolation, cosmetics
   - 2022-03-14 (OC) use single PSF file
+  - 2024-04-03 (FH) add wcu mode, move telescope yamls to individual modes
 
 packages:
   - Armazones
@@ -22,13 +23,11 @@ packages:
   - METIS
 
 yamls:
-  - Armazones.yaml
-  - ELT.yaml                # overrides below
   - METIS.yaml
 
 properties:
   instrument: "METIS"
-  modes: ["img_lm"]
+  modes: ["light", "img_lm"]
   airmass: 1.2
   declination: -30
   hour_angle: 0
@@ -60,6 +59,21 @@ properties:
   nd_filter_name: open
 
 mode_yamls:
+  - object: instrument
+    alias: OBS
+    name: light
+    description: "Normal observation mode, includes upstream telescope optics"
+    yamls:
+      - Armazones.yaml
+      - ELT.yaml
+
+  - object: instrument
+    alias: OBS
+    name: wcu
+    description: "METIS WCU calibration mode"
+    yamls:
+      - METIS_WCU.yaml
+
   - object: observation
     alias: OBS
     name: img_lm
diff --git a/METIS/tests/test_metis.py b/METIS/tests/test_metis.py
index 67171949..c4d19303 100644
--- a/METIS/tests/test_metis.py
+++ b/METIS/tests/test_metis.py
@@ -14,7 +14,7 @@
 from matplotlib.colors import LogNorm
 
 import scopesim
-from scopesim.source.source_templates import star_field
+from scopesim.source.source_templates import star_field, empty_sky
 #import scopesim_templates as sim_tp
 
 PLOTS = False
@@ -230,7 +230,7 @@ def test_something_comes_out_img_lm(self):
         src = star_field(100, 0, 10, width=10, use_grid=True)
 
         cmds = scopesim.UserCommands(use_instrument="METIS",
-                                     set_modes=['img_lm'])
+                                     set_modes=["light", "img_lm"])
         metis = scopesim.OpticalTrain(cmds)
         metis['detector_linearity'].include = False
 
@@ -257,7 +257,7 @@ def test_something_comes_out_img_n(self):
         src = star_field(100, 0, 10, width=10, use_grid=True)
 
         cmds = scopesim.UserCommands(use_instrument="METIS",
-                                     set_modes=["img_n"])
+                                     set_modes=["light", "img_n"])
 
         metis = scopesim.OpticalTrain(cmds)
         metis['chop_nod'].include = False
@@ -280,3 +280,21 @@ def test_something_comes_out_img_n(self):
             plt.show()
 
         assert mx > med + 3 * std
+
+    def test_wcu_modes_disables_upstream(self):
+        cmd = scopesim.UserCommands(
+            use_instrument="METIS",
+            set_modes=["wcu", "img_n"])
+        opt = scopesim.OpticalTrain(cmd)
+        opt.observe(empty_sky())
+        h_wcu = opt.readout()
+
+        cmd = scopesim.UserCommands(
+            use_instrument="METIS",
+            set_modes=["light", "img_n"])
+        opt = scopesim.OpticalTrain(cmd)
+        opt.observe(empty_sky())
+        h_obs = opt.readout()
+
+        # WCU must be less because atmo emission is not present
+        assert h_obs[0][1].data.mean() > h_wcu[0][1].data.mean()