diff --git a/notebooks/Jungfrau/Jungfrau_Create_Fit_Spectra_Histos_NBC.ipynb b/notebooks/Jungfrau/Jungfrau_Create_Fit_Spectra_Histos_NBC.ipynb
index f59eceda1c14960f0243ee7c18417431ec8ba09b..c6025ee092757085593441aade89e4b4405a4e24 100644
--- a/notebooks/Jungfrau/Jungfrau_Create_Fit_Spectra_Histos_NBC.ipynb
+++ b/notebooks/Jungfrau/Jungfrau_Create_Fit_Spectra_Histos_NBC.ipynb
@@ -61,7 +61,7 @@
     "n_sigma = 5.  # n of sigma above pedestal threshold\n",
     "ratio = 0.99  # ratio of the next peak amplitude in the peak_finder\n",
     "rebin_factor = 1  # Number of adjacent bins to combine before fitting the histogram.\n",
-    "\n",
+    "initial_sigma = 15.  # initial sigma used when fitting the histogram\n",
     "\n",
     "def find_das(in_folder, runs, karabo_da):\n",
     "    run = runs[0]\n",
@@ -99,7 +99,10 @@
     "from cal_tools.jungfrau import jungfrau_ff\n",
     "from cal_tools.jungfrau.jungfraulib import JungfrauCtrl\n",
     "from cal_tools.step_timing import StepTimer\n",
-    "from cal_tools.tools import calcat_creation_time"
+    "from cal_tools.tools import (\n",
+    "    calcat_creation_time,\n",
+    "    write_constants_fragment,\n",
+    ")"
    ]
   },
   {
@@ -264,7 +267,12 @@
     "jf_metadata = jf_cal.metadata(\n",
     "    calibrations=[\"Offset10Hz\", \"Noise10Hz\"])\n",
     "\n",
-    "# TODO: display CCV timestamp\n",
+    "# Record constant details in YAML metadata\n",
+    "write_constants_fragment(\n",
+    "    out_folder=(metadata_folder or out_folder),\n",
+    "    det_metadata=jf_metadata,\n",
+    "    caldb_root=jf_cal.caldb_root)\n",
+    "\n",
     "const_data = jf_cal.ndarray_map(metadata=jf_metadata)\n",
     "jf_cal.display_markdown_retrieved_constants(metadata=jf_metadata)\n",
     "\n",
@@ -360,8 +368,7 @@
     "    d -= offset\n",
     "    # Sort correct data based on memory cell order.\n",
     "    sort_indices = np.argsort(m)\n",
-    "    data_corr[index, ...] = d[sort_indices, ...]\n",
-    "    "
+    "    data_corr[index, ...] = d[sort_indices, ...]"
    ]
   },
   {
@@ -537,6 +544,7 @@
     "        rebin_factor,\n",
     "        ratio,\n",
     "        const_data[da][\"Noise10Hz\"],\n",
+    "        initial_sigma,\n",
     "    )\n",
     "    print(f\"Starting spectra fit for {len(chunks)} chunks\")\n",
     "\n",