add extent S.4.1

03_Image_Display_and_Manipulation.ipynb

@@ -270,9 +270,9 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "To see the image axes in sky coordinates instead of pixel coordinates, a simple option is to use astropy's World Coordinate System (WCS) package, along with matplotlib.pyplot's ``subplot``, ``imshow``, and ``grid`` functions. \n",
-    "Recall that we imported ``matplotlib.pyplot`` as ``plt`` already, and that we imported the ``astropy.wcs.WCS`` function as simply ``WCS``.\n",
-    "Find more information about [imshow](https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.imshow.html) and [colormaps](https://matplotlib.org/stable/tutorials/colors/colormaps.html) (``cmap``)."
+    "To see the image axes in sky coordinates instead of pixel coordinates, a simple option is to use astropy's World Coordinate System (WCS) package, along with matplotlib.pyplot's `subplot`, `imshow`, and `grid` functions. \n",
+    "Recall that we imported `matplotlib.pyplot` as `plt` already, and that we imported the `astropy.wcs.WCS` function as simply `WCS`.\n",
+    "Find more information about [imshow](https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.imshow.html) and [colormaps](https://matplotlib.org/stable/tutorials/colors/colormaps.html) (`cmap`)."
    ]
   },
   {
@@ -282,17 +282,27 @@
    "outputs": [],
    "source": [
     "fig = plt.figure()\n",
+    "\n",
     "# Set the figure's projection to be the WCS of the calexp\n",
     "plt.subplot(projection=WCS(calexp.getWcs().getFitsMetadata()))\n",
+    "\n",
+    "# Define the extent in pixel coordinates using the bounding box\n",
+    "calexp_extent = (calexp.getBBox().beginX, calexp.getBBox().endX, \n",
+    "                 calexp.getBBox().beginY, calexp.getBBox().endY)\n",
+    "\n",
     "# Display the calexp image data array using the gray colormap (cmap)\n",
     "#  and use approximately the same min and max scale values as above\n",
-    "im = plt.imshow(calexp.image.array, cmap='gray', vmin=-200.0, vmax=400, origin='lower')\n",
+    "im = plt.imshow(calexp.image.array, cmap='gray', vmin=-200.0, vmax=400, \n",
+    "                extent=calexp_extent, origin='lower')\n",
+    "\n",
     "# Add solid white grid lines\n",
     "plt.grid(color='white', ls='solid')\n",
+    "\n",
     "# Label axes\n",
     "plt.xlabel('Right Ascension')\n",
     "plt.ylabel('Declination')\n",
     "plt.show()\n",
+    "\n",
     "# Clean up memory\n",
     "remove_figure(fig)"
    ]