Find bcg tract and patch automatically

Author: plazas

DP1/100_How_to_Use_RSP_Tools/103_Image_access_and_display/103_6_Color_Composite_Image.ipynb

@@ -22,7 +22,7 @@
     "Data Release: <a href=\"https://dp1.lsst.io\">Data Preview 1</a> <br>\n",
     "Container Size: large <br>\n",
     "LSST Science Pipelines version: r29.2.0 <br>\n",
-    "Last verified to run: 2025-09-19 <br>\n",
+    "Last verified to run: 2025-10-15 <br>\n",
     "Repository: <a href=\"https://github.com/lsst/tutorial-notebooks\">github.com/lsst/tutorial-notebooks</a> <br>"
    ]
   },
@@ -816,42 +816,47 @@
    "metadata": {},
    "source": [
     "Use the BCG location to obtain the pixel scale.\n",
-    "Get the WCS of the patch and tract where the BCG is located.\n",
-    "From the 300 DP1 tutorials, the patch and tract numbers are 10463 and 62, respectively,"
+    "First, get the WCS of the patch and tract where the BCG is located."
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "8ccd5259-ffb1-45a9-bfc8-79c110301c48",
+   "id": "d92642e2-e943-4fb5-a9bb-a8eb138862e6",
    "metadata": {},
    "outputs": [],
    "source": [
-    "bcg_data_ref = next(\n",
-    "    ref for ref in tract_container\n",
-    "    if ref.dataId[\"tract\"] == 10463 and ref.dataId[\"patch\"] == 62\n",
-    ")"
+    "bcg_point = SpherePoint(ra_bcg * degrees,\n",
+    "                        dec_bcg * degrees)\n",
+    "bcg_tract = skymap.findTract(bcg_point)\n",
+    "bcg_patch = bcg_tract.findPatch(bcg_point)\n",
+    "\n",
+    "bcg_tract_number = bcg_tract.tract_id\n",
+    "bcg_patch_number = bcg_patch.getSequentialIndex()\n",
+    "print(bcg_tract_number, bcg_patch_number)"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "85859dbc-faf0-4fa4-a5f6-7a6974fd2b46",
+   "id": "8ccd5259-ffb1-45a9-bfc8-79c110301c48",
    "metadata": {},
    "outputs": [],
    "source": [
-    "wcs_bcg = butler.get(bcg_data_ref.makeComponentRef('wcs'))"
+    "bcg_data_ref = next(\n",
+    "    ref for ref in tract_container\n",
+    "    if ref.dataId[\"tract\"] == bcg_tract_number and ref.dataId[\"patch\"] == bcg_patch_number\n",
+    ")"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "133c1d9d-073b-42e3-8a2f-b782f8a9e691",
+   "id": "85859dbc-faf0-4fa4-a5f6-7a6974fd2b46",
    "metadata": {},
    "outputs": [],
    "source": [
-    "bcg_point = SpherePoint(ra_bcg * degrees,\n",
-    "                        dec_bcg * degrees)"
+    "wcs_bcg = butler.get(bcg_data_ref.makeComponentRef('wcs'))"
    ]
   },
   {
@@ -897,7 +902,7 @@
    "id": "27dbdb21-0f1a-4c32-94d7-c79f174e7ad5",
    "metadata": {},
    "source": [
-    "Set the WCS projection. The WCS of deep_coadd images are TAN projections ([see the DP1 documentation](https://dp1.lsst.io/products/images/deep_coadd.html#wcs))."
+    "Set the WCS projection. The WCS of `deep_coadd` images are TAN projections ([see the DP1 documentation](https://dp1.lsst.io/products/images/deep_coadd.html#wcs))."
    ]
   },
   {