diff --git a/.gitignore b/.gitignore
index 51d52372..7a22f8fb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -46,5 +46,4 @@ docker-compose.env.yml
 .serena
 .claude
 .playwright-mcp
-CLAUDE.md
 #tools
diff --git a/AGENTS.md b/AGENTS.md
index fef5ac1b..363cbaa5 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -114,7 +114,8 @@ MMGIS/
 ├── src/                          # Frontend source code
 │   └── essence/
 │       ├── Basics/               # Core map functionality
-│       │   └── Map_.js           # Map rendering engine (Leaflet/Cesium)
+│       │   ├── Map_.js           # Map rendering engine (Leaflet/Cesium)
+│       │   └── TimeControl_/     # Temporal data control and UI
 │       ├── Tools/                # Interactive tool plugins (16 core tools)
 │       │   ├── Animation/        # Map animation creation (GIF/MP4)
 │       │   ├── Chemistry/        # Chemical composition visualization
@@ -132,7 +133,6 @@ MMGIS/
 │       │   ├── Sites/            # Quick navigation bookmarks
 │       │   └── Viewshed/         # Line-of-sight visibility
 │       └── Ancillary/            # UI components and helpers
-│           └──TimeControl/       # Temporal data control
 ├── configure/                    # Admin configuration interface
 │   └── build/                    # Configuration UI
 ├── docs/                         # Documentation (Jekyll site)
@@ -162,6 +162,7 @@ MMGIS/
 - **`API/Backend/Databases/`** - Sequelize ORM models and database migrations
 - **`src/essence/Tools/`** - Plugin-based interactive mapping tools. Each tool is self-contained with defined interfaces.
 - **`src/essence/Basics/Map_.js`** - Core map rendering engine managing both Leaflet (2D) and Cesium (3D)
+- **`src/essence/Basics/TimeControl_/`** - Temporal data control system for time-enabled layers
 - **`configure/`** - Separate admin interface for mission configuration, user management, and tool setup. Also known as the "Configure Page" or "CMS"
 - **`specs/`** - Feature specifications following spec-kit format
 
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8ae03623..62c2c8eb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,10 @@ _TBD_
 
 #### Changed
 
+- Moved TimeControl from `Ancillary/` to `Basics/TimeControl_/` to reflect its role as core infrastructure (#835)
+  - TimeControl and TimeUI now located in `src/essence/Basics/TimeControl_/`
+  - Updated import paths across 19 files
+  - **Breaking change for external plugins**: Import path changed from `'Ancillary/TimeControl'` to `'Basics/TimeControl_/TimeControl'`
 - Moved admin login assets from `config/login/` to `public/` directory
   - `adminlogin.js` and `adminlogin.css` now served from `/public`
 
diff --git a/CLAUDE.md b/CLAUDE.md
new file mode 100644
index 00000000..bbc197ac
--- /dev/null
+++ b/CLAUDE.md
@@ -0,0 +1,7 @@
+# MMGIS - Claude Code Context
+
+This file provides context to Claude Code about the MMGIS project.
+
+**For complete project context, see AGENTS.md.**
+
+@AGENTS.md
diff --git a/configure/package.json b/configure/package.json
index f6483e24..5a7e7260 100644
--- a/configure/package.json
+++ b/configure/package.json
@@ -1,6 +1,6 @@
 {
   "name": "configure",
-  "version": "4.2.2-20251222",
+  "version": "4.2.3-20251223",
   "homepage": "./configure/build",
   "private": true,
   "dependencies": {
diff --git a/package.json b/package.json
index ca207dc6..0a21f510 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "mmgis",
-  "version": "4.2.2-20251222",
+  "version": "4.2.3-20251223",
   "description": "A web-based mapping and localization solution for science operation on planetary missions.",
   "homepage": "build",
   "repository": {
diff --git a/src/essence/Ancillary/Coordinates.js b/src/essence/Ancillary/Coordinates.js
index 7a7d3b1c..4c29b3fe 100644
--- a/src/essence/Ancillary/Coordinates.js
+++ b/src/essence/Ancillary/Coordinates.js
@@ -3,7 +3,7 @@ import $ from 'jquery'
 import F_ from '../Basics/Formulae_/Formulae_'
 import Map_ from '../Basics/Map_/Map_'
 import L_ from '../Basics/Layers_/Layers_'
-import TimeUI from './TimeUI'
+import TimeUI from '../Basics/TimeControl_/TimeUI'
 import Dropy from '../../external/Dropy/dropy'
 import * as _UserInterface_ from '../Basics/UserInterface_/UserInterface_'
 import calls from '../../pre/calls'
diff --git a/src/essence/Ancillary/Description.js b/src/essence/Ancillary/Description.js
index 18c4b5f1..34d4e1a5 100644
--- a/src/essence/Ancillary/Description.js
+++ b/src/essence/Ancillary/Description.js
@@ -5,7 +5,7 @@ import Dropy from '../../external/Dropy/dropy'
 import flat from 'flat'
 import { booleanIntersects, bbox } from '@turf/turf'
 import calls from '../../pre/calls'
-import TimeControl from './TimeControl'
+import TimeControl from '../Basics/TimeControl_/TimeControl'
 
 import tippy from 'tippy.js'
 
diff --git a/src/essence/Ancillary/QueryURL.js b/src/essence/Ancillary/QueryURL.js
index 373c7640..39aea2df 100644
--- a/src/essence/Ancillary/QueryURL.js
+++ b/src/essence/Ancillary/QueryURL.js
@@ -4,8 +4,8 @@ import F_ from '../Basics/Formulae_/Formulae_'
 import L_ from '../Basics/Layers_/Layers_'
 import T_ from '../Basics/ToolController_/ToolController_'
 import calls from '../../pre/calls'
-import TimeControl from './TimeControl'
-import TimeUI from './TimeUI'
+import TimeControl from '../Basics/TimeControl_/TimeControl'
+import TimeUI from '../Basics/TimeControl_/TimeUI'
 
 var QueryURL = {
     checkIfMission: function () {
diff --git a/src/essence/Basics/Globe_/Globe_.js b/src/essence/Basics/Globe_/Globe_.js
index b23348d8..59194b76 100644
--- a/src/essence/Basics/Globe_/Globe_.js
+++ b/src/essence/Basics/Globe_/Globe_.js
@@ -2,7 +2,7 @@ import F_ from '../Formulae_/Formulae_'
 import L_ from '../Layers_/Layers_'
 import $ from 'jquery'
 
-import TimeControl from '../../Ancillary/TimeControl'
+import TimeControl from '../TimeControl_/TimeControl'
 import GlobeRenderer from './GlobeRenderer'
 
 let Globe_ = {
diff --git a/src/essence/Basics/Layers_/LayerCapturer.js b/src/essence/Basics/Layers_/LayerCapturer.js
index c8194264..369e325a 100644
--- a/src/essence/Basics/Layers_/LayerCapturer.js
+++ b/src/essence/Basics/Layers_/LayerCapturer.js
@@ -3,7 +3,7 @@ import { utcFormat } from 'd3-time-format'
 import F_ from '../Formulae_/Formulae_'
 import L_ from '../Layers_/Layers_'
 import calls from '../../../pre/calls'
-import TimeControl from '../../Ancillary/TimeControl'
+import TimeControl from '../TimeControl_/TimeControl'
 
 // This is so that an eariler and slower dynamic geodataset request
 // does not override an earlier shorter one
diff --git a/src/essence/Basics/Map_/Map_.js b/src/essence/Basics/Map_/Map_.js
index 074cd3f6..47ba77da 100644
--- a/src/essence/Basics/Map_/Map_.js
+++ b/src/essence/Basics/Map_/Map_.js
@@ -17,7 +17,7 @@ import MetadataCapturer from '../Layers_/MetadataCapturer.js'
 import { Kinds } from '../../../pre/tools'
 import DataShaders from '../../Ancillary/DataShaders'
 import calls from '../../../pre/calls'
-import TimeControl from '../../Ancillary/TimeControl'
+import TimeControl from '../TimeControl_/TimeControl'
 
 import gjv from 'geojson-validation'
 import {
diff --git a/src/essence/Ancillary/TimeControl.css b/src/essence/Basics/TimeControl_/TimeControl.css
similarity index 100%
rename from src/essence/Ancillary/TimeControl.css
rename to src/essence/Basics/TimeControl_/TimeControl.css
diff --git a/src/essence/Ancillary/TimeControl.js b/src/essence/Basics/TimeControl_/TimeControl.js
similarity index 96%
rename from src/essence/Ancillary/TimeControl.js
rename to src/essence/Basics/TimeControl_/TimeControl.js
index 44ebdd0b..5da2c95d 100644
--- a/src/essence/Ancillary/TimeControl.js
+++ b/src/essence/Basics/TimeControl_/TimeControl.js
@@ -2,9 +2,9 @@
 import { utcFormat } from 'd3-time-format'
 import * as moment from 'moment'
 import $ from 'jquery'
-import F_ from '../Basics/Formulae_/Formulae_'
-import L_ from '../Basics/Layers_/Layers_'
-import Map_ from '../Basics/Map_/Map_'
+import F_ from '../Formulae_/Formulae_'
+import L_ from '../Layers_/Layers_'
+import Map_ from '../Map_/Map_'
 import TimeUI from './TimeUI'
 
 import './TimeControl.css'
diff --git a/src/essence/Ancillary/TimeUI.css b/src/essence/Basics/TimeControl_/TimeUI.css
similarity index 100%
rename from src/essence/Ancillary/TimeUI.css
rename to src/essence/Basics/TimeControl_/TimeUI.css
diff --git a/src/essence/Ancillary/TimeUI.js b/src/essence/Basics/TimeControl_/TimeUI.js
similarity index 97%
rename from src/essence/Ancillary/TimeUI.js
rename to src/essence/Basics/TimeControl_/TimeUI.js
index c084048e..173c963c 100644
--- a/src/essence/Ancillary/TimeUI.js
+++ b/src/essence/Basics/TimeControl_/TimeUI.js
@@ -6,12 +6,12 @@
 */
 import $ from 'jquery'
 import * as moment from 'moment'
-import F_ from '../Basics/Formulae_/Formulae_'
-import Map_ from '../Basics/Map_/Map_'
-import L_ from '../Basics/Layers_/Layers_'
-import calls from '../../pre/calls'
+import F_ from '../Formulae_/Formulae_'
+import Map_ from '../Map_/Map_'
+import L_ from '../Layers_/Layers_'
+import calls from '../../../pre/calls'
 import tippy from 'tippy.js'
-import Dropy from '../../external/Dropy/dropy'
+import Dropy from '../../../external/Dropy/dropy'
 
 import { TempusDominus, Namespace } from '@eonasdan/tempus-dominus'
 import '@eonasdan/tempus-dominus/dist/css/tempus-dominus.css'
diff --git a/src/essence/Basics/ToolController_/ToolController_.js b/src/essence/Basics/ToolController_/ToolController_.js
index 0e507199..cfa79350 100644
--- a/src/essence/Basics/ToolController_/ToolController_.js
+++ b/src/essence/Basics/ToolController_/ToolController_.js
@@ -1,6 +1,6 @@
 import $ from 'jquery'
 import L_ from '../Layers_/Layers_'
-import TimeUI from '../../Ancillary/TimeUI'
+import TimeUI from '../TimeControl_/TimeUI'
 import { toolModules, toolConfigs } from '../../../pre/tools'
 
 import tippy from 'tippy.js'
diff --git a/src/essence/Tools/Animation/AnimationTool.js b/src/essence/Tools/Animation/AnimationTool.js
index 5c94ac52..3ff9a2cd 100644
--- a/src/essence/Tools/Animation/AnimationTool.js
+++ b/src/essence/Tools/Animation/AnimationTool.js
@@ -7,7 +7,7 @@ import Viewer_ from '../../Basics/Viewer_/Viewer_'
 import ToolController_ from '../../Basics/ToolController_/ToolController_'
 import CursorInfo from '../../Ancillary/CursorInfo'
 import Description from '../../Ancillary/Description'
-import TimeControl from '../../Ancillary/TimeControl'
+import TimeControl from '../../Basics/TimeControl_/TimeControl'
 import Modal from '../../Ancillary/Modal'
 import HTML2Canvas from 'html2canvas'
 import gifshot from 'gifshot'
diff --git a/src/essence/Tools/Draw/DrawTool.js b/src/essence/Tools/Draw/DrawTool.js
index 04c541e9..f4001249 100644
--- a/src/essence/Tools/Draw/DrawTool.js
+++ b/src/essence/Tools/Draw/DrawTool.js
@@ -16,7 +16,7 @@ import Viewer_ from '../../Basics/Viewer_/Viewer_'
 import ToolController_ from '../../Basics/ToolController_/ToolController_'
 import CursorInfo from '../../Ancillary/CursorInfo'
 import Description from '../../Ancillary/Description'
-import TimeControl from '../../Ancillary/TimeControl'
+import TimeControl from '../../Basics/TimeControl_/TimeControl'
 import { Kinds } from '../../../pre/tools'
 import turf from 'turf'
 
diff --git a/src/essence/Tools/Draw/DrawTool_Templater.js b/src/essence/Tools/Draw/DrawTool_Templater.js
index 3fa15d3f..30f6b35a 100644
--- a/src/essence/Tools/Draw/DrawTool_Templater.js
+++ b/src/essence/Tools/Draw/DrawTool_Templater.js
@@ -3,7 +3,7 @@ import $ from 'jquery'
 import F_ from '../../Basics/Formulae_/Formulae_'
 import CursorInfo from '../../Ancillary/CursorInfo'
 import Dropy from '../../../external/Dropy/dropy'
-import TimeControl from '../../Ancillary/TimeControl'
+import TimeControl from '../../Basics/TimeControl_/TimeControl'
 import calls from '../../../pre/calls'
 
 import * as moment from 'moment'
diff --git a/src/essence/Tools/Layers/LayersTool.js b/src/essence/Tools/Layers/LayersTool.js
index c97f12ff..7127ad8f 100644
--- a/src/essence/Tools/Layers/LayersTool.js
+++ b/src/essence/Tools/Layers/LayersTool.js
@@ -9,7 +9,7 @@ import LayerInfoModal from './LayerInfoModal/LayerInfoModal'
 import Filtering from '../../Basics/Layers_/Filtering/Filtering'
 import Help from '../../Ancillary/Help'
 import CursorInfo from '../../Ancillary/CursorInfo'
-import TimeUI from '../../Ancillary/TimeUI'
+import TimeUI from '../../Basics/TimeControl_/TimeUI'
 
 import LegendTool from '../Legend/LegendTool.js'
 
diff --git a/src/essence/Tools/Shade/ShadeTool.js b/src/essence/Tools/Shade/ShadeTool.js
index ad1c9273..3200c877 100644
--- a/src/essence/Tools/Shade/ShadeTool.js
+++ b/src/essence/Tools/Shade/ShadeTool.js
@@ -11,7 +11,7 @@ import Map_ from '../../Basics/Map_/Map_'
 import Globe_ from '../../Basics/Globe_/Globe_'
 import CursorInfo from '../../Ancillary/CursorInfo'
 import DataShaders from '../../Ancillary/DataShaders'
-import TimeControl from '../../Ancillary/TimeControl'
+import TimeControl from '../../Basics/TimeControl_/TimeControl'
 import Help from '../../Ancillary/Help'
 
 import '../../../external/ColorPicker/jqColorPicker'
diff --git a/src/essence/essence.js b/src/essence/essence.js
index 92d4b49f..385e9c47 100644
--- a/src/essence/essence.js
+++ b/src/essence/essence.js
@@ -39,7 +39,7 @@ import MapLogo from './Ancillary/MapLogo'
 import Attributions from './Ancillary/Attributions'
 //import Swap from './Ancillary/Swap'
 import QueryURL from './Ancillary/QueryURL'
-import TimeControl from './Ancillary/TimeControl'
+import TimeControl from './Basics/TimeControl_/TimeControl'
 import calls from '../pre/calls'
 import { mmgisAPI_, mmgisAPI } from './mmgisAPI/mmgisAPI'
 import { makeMissionNotFoundDiv } from './LandingPage/LandingPage'
diff --git a/src/essence/mmgisAPI/mmgisAPI.js b/src/essence/mmgisAPI/mmgisAPI.js
index 96baec4e..aba0507d 100644
--- a/src/essence/mmgisAPI/mmgisAPI.js
+++ b/src/essence/mmgisAPI/mmgisAPI.js
@@ -2,7 +2,7 @@ import L_ from '../Basics/Layers_/Layers_'
 import F_ from '../Basics/Formulae_/Formulae_'
 import ToolController_ from '../Basics/ToolController_/ToolController_'
 import QueryURL from '../Ancillary/QueryURL'
-import TimeControl from '../Ancillary/TimeControl'
+import TimeControl from '../Basics/TimeControl_/TimeControl'
 import Login from '../Ancillary/Login/Login'
 import LegendTool from '../Tools/Legend/LegendTool.js'