diff --git a/notebooks/Gotthard2/Characterize_Darks_Gotthard2_NBC.ipynb b/notebooks/Gotthard2/Characterize_Darks_Gotthard2_NBC.ipynb
index 681022ce972c14f5b151b9e65996bb2761b61a6a..11a7a5a2d20a11a0d383bd88e5503063d804b173 100644
--- a/notebooks/Gotthard2/Characterize_Darks_Gotthard2_NBC.ipynb
+++ b/notebooks/Gotthard2/Characterize_Darks_Gotthard2_NBC.ipynb
@@ -5,9 +5,14 @@
    "id": "49b6577f-96a5-4dd2-bdd9-da661b2c4619",
    "metadata": {},
    "source": [
-    "# Gotthard2 Dark Image Characterization\n",
+    "# Gotthard2 Dark Image Characterization #\n",
     "\n",
-    "Author: European XFEL Detector Group, Version: 1.0"
+    "Author: European XFEL Detector Group, Version: 1.0\n",
+    "\n",
+    "The following is a processing for offset, noise, and Badpixels maps using dark images taken with Gotthard2 detector.\n",
+    "All constants are evaluated per strip, per pulse, and per memory cell. The maps are calculated for each gain stage that is acquired in 3 separate runs.\n",
+    "\n",
+    "The three maps (calibration constants) can be injected to the database and stored locally."
    ]
   },
   {
@@ -320,7 +325,7 @@
     "        # Select requested number of trains to process.\n",
     "        dc = run_dc.select(instr_mod_src, require_all=True).select_trains(\n",
     "            np.s_[:n_trains]\n",
-    "        )  # noqa\n",
+    "        )\n",
     "\n",
     "        step_timer.done_step(\"preparing raw data\")\n",
     "\n",
@@ -334,6 +339,14 @@
     "\n",
     "        step_timer.start()\n",
     "\n",
+    "        # The first ~20 frames of each train are excluded.\n",
+    "        # The electronics needs some time to reach stable operational conditions\n",
+    "        # at the beginning of each acquisition cycle,\n",
+    "        # hence the first ~20 images have lower quality and should not be used.\n",
+    "        # The rough number of 20 is correct at 4.5 MHz acquisition rate,\n",
+    "        # 5 should be enough at 1.1 MHz. Sticking with 20 excluded frames, as there isn't\n",
+    "        # much of expected difference.\n",
+    "\n",
     "        # Split even and odd data to calculate the two storage cell constants.\n",
     "        # Detector always operates in burst mode.\n",
     "        even_data = data_10bit[:, 20::2, :]\n",