diff --git a/ETA.py b/ETA.py
index 5342ec5..231e250 100755
--- a/ETA.py
+++ b/ETA.py
@@ -595,6 +595,61 @@ else:
     wavelength = np.arange( size_y )
 
 if verbose:
+    print( 'starting to remove artefact from intensity curve' )
+
+"""
+remove artefact
+"""
+list_ = np.convolve(
+    np.gradient(
+        np.mean(
+            data[
+                calibrations[ 'top' ][ 'y' ][ 'max' ] : calibrations[ 'down' ][ 'y' ][ 'min' ],
+                border[ 'x' ][ 'min' ] : border[ 'x' ][ 'max' ]
+            ]       ,
+            axis = 1,
+        ),
+    )            ,
+    np.ones( 50 ),
+    'same'       ,
+)
+first_stripe = np.argmax( list_ )
+range_       = range(
+    calibrations[ 'top'  ][ 'y' ][ 'max' ] + first_stripe,
+    calibrations[ 'down' ][ 'y' ][ 'max' ]
+)
+
+for line in range_:
+    abciss = range(
+        border[ 'x' ][ 'min' ],
+        border[ 'x' ][ 'max' ],
+    )
+    list_  = data[
+        line                                           ,
+        border[ 'x' ][ 'min' ] : border[ 'x' ][ 'max' ]
+    ]
+    polyfit_ = np.polyfit(
+        abciss,
+        list_ ,
+        8     ,
+    )
+
+    import matplotlib.pyplot as plt
+    plt.plot(
+        abciss,
+        list_ ,
+    )
+    plt.plot(
+        abciss,
+        np.polyval(
+            polyfit_,
+            abciss  ,
+        )     ,
+    )
+    plt.show()
+
+if verbose:
+    print( 'artefact removed from intensity curve' )
     print( 'starting bias substraction' )
 
 bias = {