diff --git a/scopesim/effects/sky_ter_curves.py b/scopesim/effects/sky_ter_curves.py
index 41f7692a5..e76cbf169 100644
--- a/scopesim/effects/sky_ter_curves.py
+++ b/scopesim/effects/sky_ter_curves.py
@@ -7,6 +7,7 @@
 from palace import palace
 import skycalc_ipy
 
+from . import AtmosphericTERCurve
 from ..utils import (get_logger, from_currsys, from_rc_config, find_file,
                      zendist2airmass, get_zenith_angle, get_moon_phase, get_observation_info_from_cmds, get_local_time)
 from .. import rc
@@ -403,3 +404,14 @@ def get_skycalc_inputs(self, **kwargs):
         return params
 
 
+class TAPASTERCurve(AtmosphericTERCurve):
+    z_order: ClassVar[tuple[int, ...]] = (111, 511)
+
+    def __init__(self, **kwargs):
+        super().__init__(**kwargs)
+        self.target, self.location, self.time, self.brightness = get_observation_info_from_cmds(self.cmds)
+        self.airmass = zendist2airmass(get_zenith_angle(self.target, self.location, self.time))
+        self.surface.table['transmission'] = self.surface.table['transmission'] ** self.airmass
+
+    def apply_to(self, obj, **kwargs):
+        return super().apply_to(obj, **kwargs)
diff --git a/scopesim/effects/spectral_trace_list.py b/scopesim/effects/spectral_trace_list.py
index ec50c9102..7d4c6a7ce 100644
--- a/scopesim/effects/spectral_trace_list.py
+++ b/scopesim/effects/spectral_trace_list.py
@@ -246,17 +246,17 @@ def apply_to(self, obj, **kwargs):
                 logger.info("Making cube")
                 obj.cube = obj.make_hdu()
 
-            # Check whether an offset slit is used. If so, recompute spectral traces.
-            offset_x = obj.cube.header["CRVAL1D"]
-            offset_y = obj.cube.header["CRVAL2D"]
-            if (offset_x != self.meta["offset_x"] or
-                offset_y != self.meta["offset_y"]):
-                logger.debug("Recomputing spectral traces for offset (%.1g, %.1g)",
-                             offset_x, offset_y)
-                self.meta["offset_x"] = offset_x
-                self.meta["offset_y"] = offset_y
-                self.make_spectral_traces()
-                self.update_meta()
+            # # Check whether an offset slit is used. If so, recompute spectral traces.
+            # offset_x = obj.cube.header["CRVAL1D"]
+            # offset_y = obj.cube.header["CRVAL2D"]
+            # if (offset_x != self.meta["offset_x"] or
+            #     offset_y != self.meta["offset_y"]):
+            #     logger.debug("Recomputing spectral traces for offset (%.1g, %.1g)",
+            #                  offset_x, offset_y)
+            #     self.meta["offset_x"] = offset_x
+            #     self.meta["offset_y"] = offset_y
+            #     self.make_spectral_traces()
+            #     self.update_meta()
 
             spt = self.spectral_traces[obj.trace_id]
             try:
diff --git a/scopesim/effects/spectral_trace_list_utils.py b/scopesim/effects/spectral_trace_list_utils.py
index 51f1906e4..ad1dd802e 100644
--- a/scopesim/effects/spectral_trace_list_utils.py
+++ b/scopesim/effects/spectral_trace_list_utils.py
@@ -256,8 +256,8 @@ def _focal_plane_grid(self, fov):
         xmin_mm, ymin_mm = fpa_wcsd.all_pix2world(xmin, ymin, 0)
         xmax_mm, ymax_mm = fpa_wcsd.all_pix2world(xmax, ymax, 0)
 
-        x_mm = np.linspace(xmin_mm, xmax_mm, sub_naxis1, dtype=np.float32)
-        y_mm = np.linspace(ymin_mm, ymax_mm, sub_naxis2, dtype=np.float32)
+        x_mm = np.linspace(xmin_mm, xmax_mm, sub_naxis1, endpoint=False, dtype=np.float32)
+        y_mm = np.linspace(ymin_mm, ymax_mm, sub_naxis2, endpoint=False, dtype=np.float32)
         return xmin, ymin, x_mm, y_mm, det_wcs
 
     def map_spectra_to_focal_plane(self, fov):
@@ -870,7 +870,7 @@ def __init__(self, fov, dlam_per_pix):
         # arrays of cube coordinates
         cube_xi = d_xi * np.arange(n_xi) + fov.meta["xi_min"].value
         cube_eta = d_eta * (np.arange(n_eta) - (n_eta - 1) / 2)
-        cube_lam = wcs_lam.all_pix2world(np.arange(n_lam), 1)[0]
+        cube_lam = wcs_lam.all_pix2world(np.arange(n_lam), 0)[0]
         cube_lam *= u.Unit(wcs_lam.wcs.cunit[0]).to(u.um)
 
         # Initialise the array to hold the xi-lambda image
diff --git a/scopesim/effects/ter_curves.py b/scopesim/effects/ter_curves.py
index 144e89e6e..340af7eab 100644
--- a/scopesim/effects/ter_curves.py
+++ b/scopesim/effects/ter_curves.py
@@ -125,8 +125,9 @@ class TERCurve
         3.0         0.9             0.1
 
     """
-    ## Made TERCurve a FOV effect as well to be able to use it for dichroic trees which act on FoV objects
-    z_order: ClassVar[tuple[int, ...]] = (10, 110, 510, 610)
+    # Even though there is a FOV block in apply_to, the default z_order for TERCurve should not have 6xx otherwise
+    # it will apply that transmission twice! Once to the source, then to the FOV, found out the hard way :(
+    z_order: ClassVar[tuple[int, ...]] = (10, 110, 510)
     report_plot_include: ClassVar[bool] = True
     report_table_include: ClassVar[bool] = False
 
@@ -688,6 +689,17 @@ def __init__(self, **kwargs):
 
     def apply_to(self, obj, **kwargs):
         if isinstance(obj, FieldOfView):
+            if obj.detector_header is not None and u.Unit(from_currsys(self.meta["position_unit"], self.cmds)) == u.pixel:
+                axis = str(from_currsys(self.meta["axis"], self.cmds)).lower()
+                if axis in {"x", "dispersion"}:
+                    detector_axis = "NAXIS1"
+                elif axis in {"y", "cross_dispersion", "cross-dispersion"}:
+                    detector_axis = "NAXIS2"
+                else:
+                    raise ValueError("axis must be 'x' or 'y'.")
+                detector_pixels = obj.detector_header[detector_axis]
+                if self._position_min() != 0 or self._position_max() != detector_pixels:
+                    warnings.warn(f"Tapered QE {axis}-axis span {self._position_min():g}..{self._position_max():g} pix differs from detector {detector_axis} span 0..{detector_pixels} pix.", stacklevel=2)
             obj.meta["detector_qe"] = self
         return obj