diff --git a/ObservationSim/Instrument/data/ccd/chip_definition.json b/ObservationSim/Instrument/data/ccd/chip_definition.json
index b1b5002804f447f74b4be7a243667369264e1edf..da04b866fc49054594648777aa2443f721ecee63 100644
--- a/ObservationSim/Instrument/data/ccd/chip_definition.json
+++ b/ObservationSim/Instrument/data/ccd/chip_definition.json
@@ -468,7 +468,7 @@
         "full_well": 90000
     },
     "15": {
-        "chip_name": "y-4",
+        "chip_name": "y-2",
         "pix_size": 0.01,
         "pix_scale": 0.074,
         "npix_x": 9216,
@@ -648,7 +648,7 @@
         "full_well": 90000
     },
     "25": {
-        "chip_name": "y-2",
+        "chip_name": "y-4",
         "pix_size": 0.01,
         "pix_scale": 0.074,
         "npix_x": 9216,