WHAT IS HELIOCLOCK?

Helioclock is a real-time Earth clock and situational awareness kiosk. It runs continuously on a dedicated device connected to a large display, showing a live picture of the Earth — day, night, weather, and space conditions updating automatically around the clock. Designed for ham radio operators, meteorologists, emergency managers, network operations centers, and anyone who needs to stay oriented to the planet at a glance.

WHAT IT DOES

Helioclock combines a real-time world map with a comprehensive suite of live data overlays and instrument panels. At its core it renders four map projections — Mercator, USA/CONUS, Globe, and Azimuthal — using NASA Blue Marble and Black Marble satellite imagery with a continuously updated solar terminator showing day and night across the planet. On top of that foundation it layers:

• Weather: GOES satellite cloud animation, NEXRAD radar with 30-frame loop, NWS watches and warnings with color-coded alert polygons, real-time GLM lightning
• Space weather: Solar activity, X-ray flux, Kp index, solar wind speed and Bz, aurora visibility, DRAP HF absorption, 3-day propagation forecast
• Ham radio: Greyline propagation windows, band conditions, DX Cluster live spots with flag identifiers, NCDXF beacon schedule, MUF matrix, azimuthal great-circle projection, ISS live tracking and amateur satellite pass predictions, PTT on-air banner, CW trainer
• Earth events: USGS earthquakes, active volcano alerts, NASA FIRMS wildfire hotspots, air quality index (AirNow / WAQI), NOAA tide predictions with chart, UV index with WHO scale and burn times
• News & situational awareness: Configurable live news crawl bar drawing from HAM radio (ARRL, AMSAT, DX Zone, RSGB), world news (AP, BBC, NPR, FOX, UPI), space (NASA, Universe Today, Spaceflight Now), weather (NWS, NHC, SPC), and geology (USGS earthquakes) feeds — with age filtering, custom feed support, and NWS alert pre-emption
• Timekeeping: UTC and local clocks synchronized via NTP, city clock bar, sunrise/sunset/twilight times, moon phase, solar position
• Display & remote view: Kiosk mode on any HDMI-connected display device; remote view from any browser on your LAN — PCs, Macs, laptops, phones, and tablets

All data updates automatically with no user interaction required.

HOW TO DEPLOY

Helioclock runs on a small dedicated computer — a Raspberry Pi 4/5 or a mini PC (such as an N100/N150-class Intel or Ryzen 5600U or better) — connected to any display via HDMI. The software is served by a local Node.js server and accessed via Chrome browser pointed at the device's LAN address. There is no internet account, no subscription, and no cloud dependency. All data pulls directly from government and public data sources to your hardware. Once running, the display operates continuously and unattended — the watchdog timer automatically recovers from any software stall, and the remote update system keeps the software current without physical access to the device.

For multi-display installations such as NOCs, EOCs, trading floors, or broadcast operations centers, the Helioclock Server SKU runs on a mini PC and serves multiple displays simultaneously over the LAN.

Helioclock supports two display modes: kiosk mode on a dedicated HDMI-connected display device, and remote view mode — access the live display from any browser on your LAN — PCs, Macs, laptops, phones, and tablets — with no additional hardware or software required.

Helioclock runs on dedicated local hardware connected to a display via HDMI. The table below covers the two supported hardware paths — Raspberry Pi and mini PC — along with requirements for remote viewing from another device on your LAN.

REMOTE VIEWING (accessing the display from another device on your LAN)

Any modern browser on the same local network — Chrome, Firefox, Safari, or Edge on a phone, tablet, or laptop. No installation required. For smart TV browser compatibility, see section 14 — REMOTE VIEW.

ENTERPRISE USE — MULTIPLE LAN REMOTE SCREENS

For installations requiring simultaneous display across multiple screens — NOCs, EOCs, trading floors, broadcast operations centers, and similar environments — rack-mounted 1U server configurations are available. Contact support@helioclock.com for details.

Use the ⏻ POWER button in the bottom bar to safely shut down or restart the system. A confirmation dialog will appear — select your action or press Escape to cancel.

POWERING ON

The Raspberry Pi 5 has a built-in power button on the board — a short press initiates a clean shutdown; press again to power back on. The Raspberry Pi 4 has no power button and powers on automatically when connected to power. Allow 30–60 seconds for Helioclock to reach the display. Mini PCs typically have a power button; press it once. The Helioclock display starts automatically — no login is required.

SHUT DOWN

Press ⏻ POWER in the bottom bar and select SHUT DOWN. The screen will show a confirmation message, then go dark. Wait for the screen to go completely dark before removing power — especially important on Raspberry Pi, where pulling power while the system is running risks corrupting the SD card.

RESTART

Two types of restart are available:

• ⏻ POWER → RESTART — full system reboot. The display goes dark for 30–60 seconds then returns automatically. Use this after a system update or if the display is behaving unexpectedly.
• RESTART SERVER button in the Admin overlay (Settings → ADMIN) — restarts only the Helioclock software, not the whole system. Faster (~5 seconds). Use this after a software update.

POWER OUTAGE / UNEXPECTED POWER LOSS

Raspberry Pi SD cards are vulnerable to corruption if power is removed while the system is running. For 24/7 installations, a UPS (uninterruptible power supply) is strongly recommended — it gives the system time to shut down cleanly when mains power is lost. If a Pi fails to boot after an unexpected outage, the SD card may need to be reflashed.

MOUSE AND KEYBOARD

A mouse is required for navigating panels, overlays, and settings. A keyboard is needed for hotkeys (Ctrl+Shift+R, etc.) and performing a hard browser reload. Both can be wired or wireless USB.

All action hotkeys use the Alt modifier. Navigation keys require no modifier.

The ⌨ KEYS button in the bottom bar opens a compact quick-reference version of this table.

Cycle views with ← → or the PREV / NEXT buttons in the bottom control bar. Open the bottom control bar by clicking the ^^ chevron centered in the bottom status bar, or press Alt+B. The bar closes automatically after 8 seconds of inactivity.

Seven map styles are available, selectable from the MAP STYLE picker in the menu:

Panels are data cards arranged in left and right sidebar columns. Each side holds up to the screen height budget — typically 4–6 half-size panels or 2–3 full-size panels.

Adding panels: Click the +/- PANELS hint at the bottom of either sidebar to open the panel picker. Select any panel to add it; select again to remove.

Panel sizes: Half-size panels show a key metric and sub-label. Full-size panels show additional detail. Click any panel to open the full detail view.

Detail view: Opens automatically when you click a panel. Auto-closes after 30 seconds. Moving the mouse inside the panel resets the timer. Press Escape to close manually. A countdown bar at the bottom of the panel shows time remaining.

📌 PIN button: Each detail panel has a 📌 pin button just below the ✕ close button. Click it to keep the panel open indefinitely — the countdown bar hides and the timer stops. While pinned, panel data refreshes every 30 seconds in the background. Click the pin again to unpin and resume the countdown. The pin resets automatically each time a new panel opens.

Hiding sidebars: Move the mouse to within 24px of the left or right screen edge — an arrow appears. Click it (or use Alt+[ / Alt+]) to slide the sidebar off-screen and reveal the map beneath. The arrow widens to 56px when the sidebar is hidden, making it easy to bring back. State is saved per browser.

Available panels — mini-panel (MP) and detail panel (DP):

The Crawl Bar
The crawl bar is a full-width ticker that appears at the bottom of the screen when an alert event fires. It displays scrolling text describing the event — event type, magnitude or severity, location, and time — in a color that reflects the alert category. An audio tone plays when the crawl first appears: a short Morse-style beep for minor events, a more prominent tone for severe ones. The crawl continues scrolling until dismissed or until the next event replaces it. Only one crawl is active at a time; a higher-severity incoming event will replace a lower-severity one already scrolling.

Dismiss the active crawl with Alt+X or the ✕ button on the right end of the crawl bar. Mute all alert audio with Alt+M — the crawl will still appear visually, only the tone is suppressed. The mute state persists until toggled off.

NEWS HEADLINE CRAWL
When no alert event is active, the crawl bar can display a continuous news ticker from a fully configurable set of RSS and ATOM feed sources. All headlines scroll as a single unbroken string — each item formatted as SOURCE: Headline · description excerpt, separated by a spaced pipe character ( | ). The ticker loops continuously until dismissed. Toggle the news crawl on and off with Alt+N, the 📰 NEWS button in the bottom control bar, or pressing Alt+X to dismiss. NWS alert crawls always pre-empt news headlines — when an alert fires, the news crawl stops immediately and the alert takes over. The news crawl resumes 3 seconds after the alert clears.

NEWS FEEDS PICKER
Configure crawl sources in the News Feeds Picker, accessible two ways: tap the ⚙ gear icon at the left end of the crawl bar (visible when the news crawl is active), or open Settings → NEWS FEEDS. The picker displays all available feeds grouped by category — HAM RADIO, WORLD NEWS, SPACE, WEATHER, GEOLOGY — each with an ON/OFF toggle, item count, last-fetched age, and a ↺ REFRESH button to force an immediate re-fetch for that feed.

Two controls at the top of the picker govern all feeds globally:

• FETCH EVERY — How often the server re-fetches each feed from its source: 15 / 30 / 60 / 120 minutes. Default: 15 minutes.
• SHOW ITEMS FROM LAST — Maximum age of items included in the crawl: 1H / 2H / 3H / 6H / 12H / 24H. Items older than this window are silently filtered out. Default: 6 hours. Weather and geology feeds publish infrequently — set this to 12H or 24H if those feeds appear empty.

If the age filter removes all items from all enabled feeds, the crawl bar shows a static notice: NO ITEMS IN RANGE · ADJUST AGE FILTER OR ENABLE FEEDS IN ⚙ NEWS FEEDS SETTINGS — a reminder to widen the window or enable additional sources.

ADDING CUSTOM FEEDS
The ADD CUSTOM FEED section at the bottom of the picker lets you add any RSS or ATOM feed by URL. Enter a name, select or type a category (existing categories are suggested; typing a new name creates a new group), enter the feed URL, pick a color swatch, then press VERIFY to test the URL before saving. VERIFY shows the item count and first headline so you can confirm the feed is live. Press ADD FEED to save. Custom feeds are stored in custom-feeds.json on the server and are never overwritten by software updates. Built-in feeds (in feeds.json) are read-only in the UI but update automatically with each Helioclock release. Custom feed rows show a ✕ delete button; built-in rows do not.

For websites that do not publish a native RSS feed, rss.app (rss.app) can generate a custom feed from almost any web page. Free tier updates every hour — suitable for most news sources. Use the resulting rss.app/feeds/[ID].xml URL in the ADD CUSTOM FEED form.

X (Twitter) feeds: X does not provide native RSS. rss.app can generate feeds from X accounts — create one at rss.app and add the resulting URL as a custom feed. Note that X actively restricts third-party scrapers, so X-sourced feeds may be less reliable than native RSS sources and could stop working without notice. For official sources (NWS, NHC, USGS, ARRL, etc.) the native RSS feeds listed above are always preferable.

Step-Up Deduplication
Each alert rule tracks the highest level it has already announced. Once a crawl has fired for an event at a given threshold, it will not fire again for the same event at the same level — preventing the same earthquake or storm from re-crawling every time the data refreshes. The crawl fires again only if the event escalates to a higher threshold — for example, if a geomagnetic storm steps up from G1 to G2. The deduplication state resets automatically when the event clears or when Helioclock restarts.

Configuring Alert Rules
Open Settings → Alerts → Alert Rules. Each rule has an ON/OFF toggle and a threshold selector. Setting a rule to OFF disables both the crawl and the audio for that event type entirely. The threshold sets the minimum severity required to trigger — events below the threshold are silently ignored even if the rule is ON.

NWS Weather Alerts
National Weather Service alerts are fetched every 5 minutes from the NWS API and displayed as color-coded polygon overlays on the USA and Mercator map views. The same alerts feed the crawl bar. Coverage is CONUS only — Alaska, Hawaii, and US territories are not covered by this feed.

Alert severity levels and crawl colors:

The per-event-type toggles in Alert Rules let you enable or disable crawl notifications for individual NWS event types. For example you can enable Tornado Warnings and disable Winter Weather Advisories if you live in a region where the latter are routine. The polygon overlays on the map are always shown for all active alerts regardless of which crawl toggles are enabled — the toggles only control whether a crawl bar and audio tone fires for that type.

NWS alert polygons on the map are hit-testable — hover any colored polygon to see a tooltip showing the event name, affected area description, and expiry time. Polygons are drawn above the radar animation layer so they are always visible during active weather.

Space weather data is fetched from NOAA SWPC every 15 minutes.

SOLAR ACTIVITY — Detail Panel
Click the Solar Activity panel to open the full detail view. The left column shows a live 512×512 NASA SDO image with the image type labeled above it. Use the wavelength buttons below the image to switch views: VISIBLE (white light sunspots), CORONA (hot plasma loops), EUV (extreme ultraviolet), CHROM (chromosphere), MAGNET (magnetogram), and FLARES (flare-sensitive 131Å). The ACE IMF button switches to the ACE real-time solar wind plot served as a full-color PNG from the server. The right side shows all solar indices in two columns. The full-width chart at the bottom shows the 30-day sunspot number trend — hover for date and SSN value.

X-RAY FLUX & TREND — Detail Panel
Click the X-Ray Flux panel to open the trend view. The left side shows the current flux class, log-scale bar, and radio blackout R-scale. The right side shows peak flares and HF blackout severity. The full-width chart at the bottom shows the 3-day X-ray flux trend color-coded by flare class — hover for class, flux value, and timestamp.

LIGHTNING — Live Lightning Scope
Click the Lightning panel to open the Live Lightning Scope. A circular scope display shows all NOAA GOES-19 GLM strikes within range of your QTH or a custom center location. Range rings are drawn at 25%, 50%, 75%, and 100% of the selected radius. County boundaries, major roads, and nearby city labels are drawn as a geo reference layer inside the scope.

Strike display: Each strike is plotted as a color-coded dot scaled by flash energy. ● WEAK (<10 J) — yellow dot. ● MODERATE (10–100 J) — orange dot. ● STRONG (100–1000 J) — red dot. ● INTENSE (>1000 J) — red dot with glow halo. Dots fade over 2 minutes as strikes age. Hover any dot for a tooltip showing energy class, time ago, distance in miles, and bearing from scope center (e.g. 3.2 MI · NNE 024°).

Title bar stats: STRIKES (within range count), RATE (per minute), and NEAREST (closest strike distance) are shown in the title bar across the top of the scope — always visible regardless of scroll position.

Range buttons: 10 MI / 25 MI / 50 MI — select the scope radius. Located in the lower-left corner outside the scope ring. Default is 10 MI.

Nudge controls: Eight arrow buttons positioned around the outside of the scope ring (N, NE, E, SE, S, SW, W, NW) pan the scope center in that direction. Each nudge moves the center by 20% of the current range radius. Use nudging to explore a moving storm without typing a new location.

Scope center: Use the SCOPE CENTER input at the bottom to enter any US zip code or city/state (e.g. 33602 or Tampa, FL) to recenter the scope on that location. Hit Enter or SET to geocode; RESET TO QTH returns to your station location. The center is temporary and clears when the panel closes.

Proximity alert: An audible Morse/beep tone fires when any strike occurs within range of the scope center — 5-minute cooldown between alerts. Data source: NOAA GOES-19 GLM, Western Hemisphere coverage (~141°W–9°E, 54°N–54°S), 5-minute rolling window, updates every 20 seconds.

NEXRAD RADAR — Radar Scope
Click the NEXRAD Radar panel to open the Radar Scope. A circular scope display shows current radar reflectivity data centered on your QTH or a custom center, sourced from RainViewer and remapped to the Helioclock TV palette (green → yellow → orange → red). County boundaries, major roads, and nearby city labels are drawn as a geo reference layer inside the scope — the same layer used by the Lightning Scope.

Range buttons: 10 MI / 25 MI / 50 MI / 100 MI — select the scope radius. Located in the lower-left corner of the scope. At 100 MI zoom level 6 tiles are used; at 50 MI and below, zoom level 7 tiles provide higher resolution. Default is 10 MI.

Nudge controls: Eight arrow buttons around the outside of the scope ring pan the center in any compass direction, identical to the Lightning Scope. Use nudging to track a storm cell moving through your area.

NWS polygon overlays: Active National Weather Service watches, warnings, and advisories are drawn as semi-transparent color polygons on top of the radar data — the same polygons shown on the main map. Hover any polygon to see the event type, affected area, and expiry time. Alert colors follow NWS standards: ■ Tornado Warning, ■ Severe Thunderstorm Warning, ■ Watch, etc.

Scope center: Use the SCOPE CENTER input to enter any US zip code or city/state to recenter on that location. RESET TO QTH returns to your station. The center is temporary.

Updated timestamp: The UPDATED label in the lower-right shows how old the current radar tile is. The scope refreshes automatically every 30 seconds while open. Data source: RainViewer public API, free for personal use, ~2-minute latency behind real-time.

Ham radio features are available on all tiers. Some require QTH location to be set in Settings.

Helioclock provides two complementary ways to view aviation weather (METAR) data — a personal station panel for your location, and a map overlay for monitoring multiple stations at a glance.

WEATHER MINI-PANEL (sidebar)
The Weather mini-panel shows current conditions at the METAR station nearest to your QTH, or at a station you specify manually via Settings → Weather Station Override. Click the mini-panel to open the full Detail Panel, which shows decoded current conditions and four scrollable history graphs covering the past 24 hours:

METAR MAP LAYER
The METAR Stations layer plots up to 50 user-selected aviation weather stations directly on the Mercator and USA map views. Enable it via ≣ LAYERS → METAR STATIONS. When first enabled, the station picker opens automatically. Once the layer is on, tap the ✎ edit button next to the toggle at any time to add or remove stations.

Adding stations: Type an ICAO code (e.g. KRNO) or city/airport name (e.g. New Orleans, Chicago, London) into the search box. Each result shows two add buttons — ICAO to label the dot with the station code, or CITY to label it with the location name. Use ⇄ on any selected station tag to switch the label at any time. Tap ✕ on a tag to remove it. Selections are saved across sessions.

On the map: Each station appears as a cyan dot with a sky condition icon and current temperature. Hover over any dot to see the full observation.

Data source: NWS/NOAA tgftp decoded METAR (primary) · Aviation Weather Center fallback per station · 8,509-station global database bundled locally — no internet required for station search · Observations refresh every 5 minutes · Data updated every 20–60 minutes depending on station type.

Note: The Weather mini-panel and the METAR map layer share the same underlying NOAA METAR data. The mini-panel always shows your home station; the map layer lets you monitor any combination of stations worldwide simultaneously.

A Morse code training tool with two modes: Sending Practice (you key, Helioclock decodes and scores) and Receiving Practice (Helioclock generates CW audio, you copy). Access via ⋮ MENU → CW TRAINER.

Sending Practice: Select card type (Callsigns / QSO / Q-Codes / Words / Numbers / Koch), key the displayed text. SENT row shows symbols live; DECODED row hides while keying and reveals 800ms after pause. Score = Levenshtein accuracy % vs target. Spacebar = manual key for testing without hardware.

Receiving Practice: Set WPM (5–40) + optional Farnsworth spacing, click PLAY. Type what you hear, click SCORE. REVEAL shows sent text without scoring. SKIP advances to next card.

Koch method: Starts with K and M. Use +/− to add one character at a time following the ITU Koch sequence.

Pi GPIO wiring: GPIO 17 = physical Pin 11. GND = Pin 9. Paddle tip between Pin 11 and Pin 9. For two-paddle iambic: dit to GPIO 17 (Pin 11), dah to GPIO 27 (Pin 13), shared GND to Pin 9.

Note: this is a separate pin from PTT Monitor's GPIO input (BCM GPIO 21 / physical pin 40 — see Section 09). The CW key and PTT are wired to different pins and can be used at the same time without conflict.

AIR QUALITY PANEL

The Air Quality panel shows the current AQI (Air Quality Index) for your QTH using the US EPA standard six-level color scale. The mini panel displays the numeric AQI, category badge, dominant pollutant, and reporting station name. The detail view adds a full pollutant breakdown (O3, PM2.5, PM10, CO, NO2, SO2), the AQI color scale reference, and a multi-day forecast when available.

Two API keys are required — both are free with registration:

• AirNow (US / Canada / Mexico) — register at airnow.gov → Developers/API
• WAQI (global fallback for all other locations) — register at aqicn.org/data-platform/token

Enter both keys in Settings → Profile. AirNow is used automatically when your QTH is within North America; WAQI covers the rest of the world. If neither key is configured the panel shows SET API KEY. Data refreshes every 30 minutes.

TIDES PANEL

The Tides panel shows NOAA CO-OPS tide predictions for a station of your choice. No API key is required. Enter a NOAA station ID in Settings → Profile → TIDE STATION to activate the panel. Find station IDs at tidesandcurrents.noaa.gov/tide_predictions.html — search by region, then note the 7-digit ID shown in the URL (e.g. 9414290 for San Francisco).

The mini panel shows the station name and the next predicted HIGH and LOW with times and heights in feet. The detail panel shows:

• Top left: Station name, ID, distance from QTH, datum (MLLW)
• Top right: Full hilo schedule — today and tomorrow — with local time, UTC time, and height for each H/L event
• Bottom: Full-width 48-hour tide chart with gradient fill, H/L markers with heights, current time indicator (green line), and today/tomorrow labels

Chart tooltips: Hover anywhere on the tide chart to see a floating tooltip showing local time, UTC, and water height at that point. The chart covers 48 hours from midnight today.

Primary vs subordinate stations: NOAA primary (reference) stations provide continuous 6-minute prediction data which is used directly for the chart. Subordinate stations (which reference a nearby primary) only provide high/low predictions — Helioclock automatically generates a smooth chart curve from those points using cosine interpolation between H/L pairs. Both station types are fully supported; the chart looks the same either way.

Tide predictions refresh hourly. All times display in both local time and UTC.

UV INDEX PANEL

The Ultraviolet (UV) Index predicts the UV radiation levels on a 1–11+ scale. The UV Index provides a daily forecast of the expected intensity of UV radiation from the sun. Higher values increase the chance of sunburn.

The mini panel shows the current UVI, WHO category badge, and today's forecast maximum with time. The detail panel shows current reading, today and tomorrow maximums, the full WHO five-level scale, and a color-coded 48-hour bar chart — bars are colored green through violet by exposure level. Hover anywhere on the chart for time and UVI value. No API key is required. Data is fetched from Open-Meteo for your QTH location and refreshes hourly.

UV Index scale (WHO standard): Low 0–2 · Moderate 3–5 · High 6–7 · Very High 8–10 · Extreme 11+

The Quick Reference overlay provides a built-in ham radio desk reference. Press Alt+R from the main display to open it. Navigate between tabs with Tab (forward) or Shift+Tab (back). Close with ESC or the ✕ button.

Remote View lets you access Helioclock from any other device on your local network — a laptop, desktop, tablet, or smart TV — without installing anything. If the remote browser shows stale content or a previous version of the page, press Ctrl+Shift+R (or ⌘+Shift+R on Mac) to hard reload and pick up the latest version from the server. Open ⋮ MENU → TOOLS → REMOTE VIEW to see your network addresses and QR codes.

Type the displayed URL into a browser on the other device and Helioclock will load fully live and interactive, just as it appears on the kiosk.

Remote browsers maintain their own independent settings profile stored on the server. The first time a new browser connects, it automatically receives the kiosk's saved settings as a starting point — QTH, callsign, timezone, active panels, and all preferences — so it comes up fully configured instead of blank. After that first load, the remote browser has its own profile; changes you make on a remote browser do not affect the kiosk or other remote browsers. To manually re-sync at any time, open ⚙ Settings → ⟳ SYNC FROM KIOSK.

BIG SCREEN TVs & SMART TV BROWSERS

Helioclock is designed to run on dedicated hardware — a Raspberry Pi 4/5 or a mini PC — connected to your TV via HDMI. The TV is just a display; all processing happens on the Helioclock device. This is the recommended path for every TV platform and gives the best performance, full feature support, and automatic updates.

As a secondary option, many smart TVs include a built-in browser that can access Helioclock directly over your LAN. Compatibility varies significantly by platform.

NO BROWSER ON YOUR TV?

If your TV platform has no usable browser, the simplest solution is a small dedicated PC connected via HDMI. Any of the following will work:

• Raspberry Pi 4 or Pi 5 — the Helioclock SD card SKU is purpose-built for this
• Mini PC (N100/N150-class Intel or Ryzen 5600U or better) — fanless, silent, runs 24/7, powers the Helioclock Server SKU
• Any spare Windows or Linux PC with Chrome installed

Connect the device to your TV via HDMI, open Chrome, navigate to http://[your-helioclock-IP], and press F11 for fullscreen. The TV becomes a full kiosk display with no remote-control limitations.

TIPS FOR TV BROWSER USE

• Always use http:// and the IP address — do not use helioclock.local on TV browsers
• GOES cloud and radar layers load slower on TV browsers than on desktop Chrome — wait 30 seconds before assuming something is broken
• All interactive elements (timezone picker, layer toggles, panel close buttons, scrollbars) are sized for remote pointer navigation
• If the address bar forces https://, type the full URL including http:// to override it
• TV browsers control their own rendering resolution independently of the panel's physical resolution. A 4K TV may render the browser at 1280×720 and upscale — this is a browser limitation outside Helioclock's control and cannot be changed from the page.

Helioclock renders at your display's native resolution and uses your operating system's scaling factor to determine text and element sizes. Getting this right is important for crisp, readable text — especially on 4K displays.

1080p DISPLAYS
No special configuration is required. Set your display to its native 1920×1080 resolution. Text and graphics will render crisply at 100% scale.

4K DISPLAYS (3840×2160)
A 4K display connected to a Helioclock appliance should be configured as follows for best results:

1. Open Settings → ADMIN → ⚙ DISPLAY SETTINGS — this opens the OS display configuration panel
2. Set Resolution to 3840×2160 (native 4K — do not reduce to 1080p)
3. Set Scale (also called Magnification or Display Zoom) to 200%
4. Apply and close

Running at native 4K resolution with 200% scale tells Helioclock to render every pixel at full 4K sharpness while keeping all UI elements at a comfortable viewing size. Setting the resolution to 1080p instead causes thin, broken-looking text because the browser renders at low resolution and the display upscales it.

WHY NOT JUST SET IT TO 1080p?
A 4K display set to 1080p resolution loses its native pixel mapping. The TV or monitor must electronically upscale the 1080p image to fill its 4K panel — this interpolation produces soft, slightly blurry rendering. Running at native 4K with OS-level scaling avoids this entirely.

ACCESSING DISPLAY SETTINGS
From within Helioclock, open Settings → ADMIN → ⚙ DISPLAY SETTINGS. The OS display configuration panel will appear on top of the kiosk — no need to exit. Make your changes, close the panel, and Helioclock continues running normally.

SETTINGS PERSIST ACROSS REBOOTS
Once you configure the correct resolution and scale, the settings are saved by the OS and restored automatically on every boot. You only need to set this once.

DISPLAY TEST PATTERNS
Open Settings → ▦ DISPLAY TEST PATTERNS for six built-in calibration patterns — useful when setting up a new display, checking an old monitor or TV before connecting it to a shack Pi, or verifying a signage installation. Pick a pattern, tap FULLSCREEN (hides all Helioclock UI, not just the settings box), then tap anywhere to cycle through: SMPTE Color Bars, Crosshatch, Grayscale, HD SMPTE RP 219:2002 Color Bars, five Solid Colors (red/green/blue/white/black), and Geometry. Tap the top-left corner or press Esc to exit back to Settings.

• SMPTE Color Bars — real 75% amplitude broadcast values, classic 3-tier layout (color bars / castellation strip / black-level reference strip). Checks hue accuracy and color balance. Plays a continuous 1kHz reference tone at -20dBFS (the standard "bars and tone" broadcast convention) — mute button available on the pattern itself. If a callsign is set in Profile, it's shown in the bottom-right of the black strip, making this pattern usable as a properly-identified SSTV calibration/test slide as well.
• Crosshatch — grid, center crosshair, and alignment circle. Checks geometry, convergence, and pixel-level sharpness.
• Grayscale — 16-step ramp from black to white. Checks black level, white level, and gamma/banding.
• HD SMPTE RP 219:2002 Color Bars — the modern HD broadcast color bar standard, distinct from the classic SMPTE Color Bars pattern above. Neutral grey margins framing the main bars, a full-bright cyan/blue reference row, a black-to-white luma ramp, and a complete PLUGE black-level reference set (including "blacker than black" and "whiter than black" patches) in the bottom row.
• Solid Colors — full-screen red, green, blue, white, and black in sequence. Checks uniformity, backlight bleed, and dead/stuck pixels.
• Geometry — concentric circles, diagonals, and a safe-area rectangle. Checks aspect ratio distortion and overscan cropping.

HOW TO USE EACH PATTERN

• SMPTE Color Bars / HD RP 219:2002 Color Bars — Adjust your display's color/tint controls until the grey reference bar looks neutral, with no visible color cast. If your TV has a "blue only" picture mode, use it — the blue bars in each row should all match in brightness.
• Crosshatch — The grid lines should be straight and evenly spaced edge to edge. The center circle should look perfectly round; an oval shape means the image is being stretched non-uniformly.
• Grayscale — Step through the 16 blocks from black to white. Each should be clearly distinct from its neighbors — several dark steps blending together means black level/contrast is too high; steps near white blending together means brightness is too high.
• Solid Colors — Watch each full-screen color for patches, blotches, or brighter/dimmer spots, which indicate backlight bleed or panel uniformity issues. On the black screen, check in a dark room for any pixels that stay lit (stuck pixels).
• Geometry — Confirm the circles are round, not stretched into ovals. If the outer safe-area rectangle gets cut off at your screen's edge, your display or TV is applying overscan and cropping part of the image.

The kiosk display runs in a locked-down Chromium session with the print dialog suppressed — you cannot print directly from the screen in front of you. All printing and sharing is done from a second device (phone, tablet, laptop) on the same LAN.

Sharing a live view
Open http://helioclock.local/ on any device on your LAN. You get a fully live, interactive copy of the display in your browser. From there you can screen-share the browser tab in any video call (Zoom, Teams, Google Meet, FaceTime), cast it to a TV via Chromecast or AirPlay, or simply hand your phone to someone. The Remote View QR code shown in the lower-right corner of the kiosk display links directly to this URL — scan it with any phone to open a live view instantly. See Section 12 (Remote View) for full details.

Capturing a still image of the current kiosk screen
Open http://helioclock.local/api/kiosk-snapshot from any browser on your LAN. The server captures exactly what is showing on the kiosk display at that moment and delivers a full-resolution PNG to your browser. The image opens inline — right-click it to save, or use your browser’s share sheet to send it directly to a contact, post it to QRZ.com, or drop it into a club forum. The snapshot reflects the live display including all active panels, layers, and animations — frozen at the instant you loaded the URL.

Printing the current kiosk screen
Open http://helioclock.local/api/kiosk-snapshot on a device connected to your printer. The PNG loads in your browser. Press Ctrl+P (or ⌘+P on Mac) and print normally. For best results choose landscape orientation and “fit to page” in your print dialog. A color printer will produce a useful reference image showing current band conditions, solar data, active alerts, and greyline status at the time of capture.

Printing this help file
This help file is accessible at http://helioclock.local/help from any browser on your LAN. Open that URL and press Ctrl+P. The help file includes a print stylesheet that removes the dark background, switches to black text on white, and formats the tables cleanly for paper. All 21 sections print in order. Suggested print settings: portrait, all pages, default margins.

If the snapshot returns an error
The snapshot feature requires Chromium to be started with the --remote-debugging-port=9222 flag. This flag is included in the Helioclock kiosk autostart configuration. If you see an error message when loading the snapshot URL, contact support or reinstall Helioclock. The debugging port is bound to localhost only and is not accessible from other devices on your LAN — it is used exclusively by the Helioclock server to capture screenshots.

Helioclock updates itself automatically from a private GitHub repository. No manual steps are required for normal operation — updates download and apply overnight while the display is running.

AUTOMATIC UPDATES

The server checks for new releases once daily at a randomized time offset — the randomization prevents all units from hitting the repository simultaneously on a large deployment. If a newer version is available, it downloads the complete update to a temporary location first, verifies it, then replaces the running files in a single step. A partial or failed download can never corrupt your installation. After a successful update the service restarts automatically — the display goes briefly dark then returns on its own. No user action is required.

ADMIN PAGE

The Admin overlay (Settings → ADMIN) shows the current installed version, the time of the last update check, and a CHECK NOW button to trigger an immediate check outside the daily schedule. Use this after a known release to pick it up right away rather than waiting for the overnight check.

WHAT GETS UPDATED

Updates replace the three application files: helioclock.html, server.js, and help.html. Your personal configuration — QTH location, callsign, settings, panel layout, and any custom data — is stored in server-config.json and is never touched by an update.

IF AN UPDATE FAILS

If the download fails or the integrity check does not pass, the running files are left untouched and the previous version continues operating normally. The Admin overlay records the failure reason. The next daily check will retry automatically.

GITHUB ACCESS TOKEN

The update system uses a read-only personal access token stored locally in server-config.json. This token has permission to read release assets only — it cannot write to or modify the repository in any way. The token is injected during installation and is never baked into the distributed image.

DAILY BROWSER RESTART — 3:00 AM

Helioclock automatically restarts the Chrome browser every night at 3:00 AM (±60 seconds). This is a normal and intentional maintenance window — the display goes dark for approximately 30 seconds then returns on its own. No user action is required. If any animated layers (GOES satellite clouds or radar) were active before the restart, they may need to be re-enabled manually after the display returns. All other settings and panels are unaffected.

UPDATE PREFERENCES

Update behavior is configured in Settings → ADMIN → UPDATE PREFERENCES. Three modes are available:

UPDATE BANNERS

When NOTIFY ON-SCREEN is enabled, two banners may appear in the upper-left corner of the display:

• GOLD BANNER — Update available. Shows the new version number. Click the banner or press Alt+U to open the Admin overlay and apply the update manually.
• CYAN BANNER — Update was applied automatically overnight. Shows the new version. Click the banner or press Alt+U to dismiss. Stays on screen until dismissed so the operator knows the system updated.

In UNATTENDED MODE, no banners appear regardless of NOTIFY ON-SCREEN setting.

STATUS BAR INDICATORS

The bottom bar displays four live status indicators on the right side. Each has a colored dot and a label — green indicates normal operation, amber indicates a degraded or recent-restart condition, red indicates a fault or offline state.

The Helioclock admin panel is accessible via the ⚙ ADMIN button at the bottom of the Settings panel (⚙ button in the bottom bar). It opens as an overlay and is also available to any device on the same LAN at http://helioclock.local/admin.

Health Report — The top section of the admin panel shows a live system health snapshot. It loads automatically each time the admin panel opens, and a 🩺 REFRESH button re-polls on demand. All values are color-coded: green = normal, amber = warning, red = critical.

GitHub Configuration — Enter your GitHub repository name (format: Owner/reponame) and a Personal Access Token with Contents read-only permission. Press SAVE. These are stored in settings/server-config.json on the server and persist across restarts.

Software Update — Press CHECK NOW to query GitHub Releases for the latest release tag. If the tag differs from the running server version, STATUS shows UPDATE AVAILABLE and an APPLY UPDATE button appears. Pressing APPLY UPDATE downloads only the files attached as assets to that release, verifies each file, performs an atomic swap, then restarts the server. The page reloads automatically after 8 seconds.

Partial updates — A release does not need to include all four files. If only help.html changed, only help.html needs to be attached to the release. Only files present as release assets are downloaded and updated.

Auto-check — The server automatically checks for updates once daily at 3AM local time (plus a random 0–60 minute offset to avoid simultaneous checks from multiple units).

UPDATE PREFERENCES — Three checkboxes appear in a single row:

First-Run Network Setup — On first boot, a NETWORK SETUP screen appears before the main display loads. Choose how this Helioclock will connect to the network:

This screen appears only once. After a successful connection it is dismissed permanently. To re-run network setup, open the WIFI section in the Admin panel at any time.

WiFi (Admin panel) — The WIFI section in the Admin panel lets you change or re-configure the wireless connection after first boot. Press SCAN to list available networks, click a name to select it, enter the password, and press CONNECT.

System Password — Press CHANGE PASSWORD to expire the current administrator password. You will be prompted to set a new one at the next SSH or console login. The default password set during installation is Helioclock#1 — change it before deploying in any shared environment.

Helioclock is a real-time living world clock and kiosk display for amateur radio operators, Earth systems enthusiasts, and weather professionals. Continuing the tradition established by HamClock (WB0OEW). Designed and developed by KA9NWM.

Website: helioclock.com
Current version shown in the header and the About screen (⋮ Menu → About).

© 2026 Helioclock. All rights reserved. Data from third-party sources is provided as-is. Do not rely on Helioclock as your sole source of severe weather or emergency information.

DATA SOURCES

Common fixes for display, data, and server issues.

SERVER ACTIONS

These buttons act on the Helioclock server. Use with care on the primary kiosk display — the screen will go blank briefly on restart.

Is there a central Helioclock server? What happens if it goes offline?
No. Helioclock runs entirely on your local hardware — the Pi 4/5 or mini PC sitting on your desk. There is no cloud dependency, no subscription server, and no single point of failure outside your own LAN. All data feeds (NOAA, RainViewer, NASA, NWS) are fetched directly from their public APIs by your local server. If any individual data source goes down, that layer shows stale or no data — but the rest of the display keeps running. The display itself will continue operating indefinitely on your LAN even if your internet connection drops entirely. This is a deliberate architectural choice, directly addressing the HamClock situation where the author's personal server going EOL ended the product for every user simultaneously.

Why doesn't the MUF Matrix use real VOACAP? Is it a cheaper substitute?
It's a deliberate tradeoff, not a shortcut. Genuine VOACAP-grade prediction is real, expensive computation — commercial services that offer it as an API run it centrally, on their own servers, and require an ongoing subscription to reach it. That's precisely the dependency Helioclock's whole architecture exists to avoid: no Helioclock feature should stop working because a company's server, pricing, or licensing terms changed. So the MUF Matrix computes an honest, simplified secant-law estimate entirely on your own device — live sunspot number and Kp feed a real, cited ionospheric relationship (see Credits & Data Sources), rendered locally with no ongoing cost and no external dependency beyond the solar data feed itself. It won't match a real VOACAP engine's regional accuracy — it doesn't have decades of ionosonde measurement data behind it — but it will never go offline because someone else's server did, and it will never come with a bill.

Why does the Contest Calendar not come with any events pre-loaded?
Because the best available contest calendar data — the WA7BNM Contest Calendar — is a licensed resource, and its own published Terms of Use draw a clear line: loading its ICS feed into a calendar application for your own personal use is already freely permitted, but a product bundling and redistributing that data to every customer by default would need a separate written agreement with its owner. Helioclock's Contest Calendar panel is built to match the use that's already permitted — you point it at a feed of your own choosing in Settings → Data Sources, the same way you'd add any external calendar to Outlook or Google Calendar, and your unit fetches that feed directly. Nothing is bundled or redistributed centrally. Any public ICS/iCalendar feed works, not just WA7BNM's — it's your choice, not a Helioclock default.

What makes Best Band Now different from other propagation dashboards?
Most tools show one number per band — a model's prediction, or a count of live spots — but not both compared against each other. Best Band Now shows a QTH-anchored MUF prediction alongside live evidence for every band at once, ranked by a single score rather than sorted into a few fixed categories — and it shows its work: every band's evidence, MUF headroom, and resulting score is visible in the leaderboard, not just the winner. A band the model predicts Closed but that's showing real activity anyway appears in a separate Surprise Activity section — a sign the model missed something, often sporadic-E or an unusual opening, and often a more useful signal than the main ranking alone. Each band also gets its own "Band Scope" — a small sparkline of that band's score over the last hour, so you can see whether it's a fluke spike or a sustained trend at a glance, something no other propagation tool currently offers. Confirmation evidence comes from Reverse Beacon Network CW skimmer spots of any beacon station and DX Cluster spot counts. Neither carries real coordinates for the spotting station, so a band opening on the other side of the world can currently contribute to that band's score here too — an honest limitation worth knowing. Two other sources were tried and removed: PSK Reporter (digital-mode-only, only shows anything while you're actively transmitting, read zero most of the time) and POTA (distance-filtered to genuinely nearby parks — technically correct, but with so few nearby parks active at any given moment it also read zero most of the time, which looks exactly like "broken" to anyone glancing at the panel even though the number was honest).

Exactly how is each band's score and the overall "best band" pick calculated?
Prediction: the same simplified secant-law MUF model as MUF Matrix, but evaluated at your own QTH coordinates instead of one of MUF Matrix's 8 fixed world regions. A band is Open if its frequency is at or below 88% of the computed MUF, Marginal between 88% and 105% of MUF, and Closed above 105% — the same thresholds MUF Matrix itself uses, so the two panels stay consistent with each other. The Δ MUF column shows the plain MHz difference (computed MUF minus the band's frequency) so you can see the actual margin behind the number, not just the predicted category.

Evidence: the same two sources as before, but now feeding a score directly rather than clearing a pass/fail bar. RBN (Reverse Beacon Network) counts any CW skimmer spot of any beacon station in the last 15 minutes. This originally only counted the 18 official NCDXF/IARU network beacons specifically, but that was checked against real RBN traffic and found to read zero almost as often as POTA did, for a real structural reason: those 18 beacons share a rotating schedule (each transmits only 10 seconds out of every 180), while the RBN feed is otherwise dominated by many independent, always-on personal beacon stations. Counting any beacon spot trades some precision for actually having data most of the time. DX Cluster counts spots in the last 15 minutes, anywhere in the world (a known limitation shared by both sources: spotting-station location isn't yet cross-referenced against your own QTH, so a global opening elsewhere can currently contribute here too). The EVIDENCE column shows the raw DX and RBN counts side by side so you can see exactly what's feeding the score. PSK Reporter and POTA were both tried as additional sources and removed — see the FAQ above for why.

Score: every band predicted Open or Marginal gets one number: log(DX + RBN spots + 1) × frequency weight × 10 + MUF headroom bonus. The evidence count is log-scaled so a burst of 60 spots doesn't need to beat 6 spots by an absurd margin — going from 1 to 10 spots matters more than going from 60 to 70. The frequency weight runs from 1.0× (80m) to 2.0× (6m), reflecting that higher bands are generally quieter and more valuable when they're genuinely open, not that they're intrinsically "better" propagation. The MUF headroom bonus is small and capped, rewarding a band that sits comfortably below the computed MUF over one right at the edge, without ever letting headroom alone decide the outcome. Whichever band has the highest score is ranked #1 — the leaderboard always shows every band's real score in ranked order, nothing hidden or pre-filtered.

LEADING vs. CONFIRMED — why is the #1 band sometimes not "confirmed" yet? A band sitting right at the top of the ranking can genuinely swap places with a close second every few minutes as individual spots age in and out of their 15-minute windows, even though nothing real is changing. Rather than let the "best band" flip back and forth on every such wobble, whichever band currently ranks #1 must hold that rank continuously for 20 minutes before it's marked CONFIRMED (green); until then it shows LEADING (amber) with a running "X/20 MIN" counter. This 20-minute hold was arrived at by testing several variants directly against a real multi-day decision log before picking one. Importantly, this hold applies only to that one badge — the ranking and every band's score are never delayed or hidden, so nothing on screen contradicts what the "best" verdict is quietly waiting to confirm.

Band Scope: a small sparkline shown for every band (not just the leader — leaving one out reads as a bug, not a deliberate omission), plotting that band's own score over the last 60 minutes. Each sparkline is scaled to that band's own range, not a shared scale across all 9 bands, since the point is showing shape and trend at a glance, not absolute magnitude — but the actual min–max range behind that shape is always printed directly underneath it, so a small wiggle and a dramatic swing can never look visually identical without the real numbers to tell them apart. It's seeded from the existing decision log on page load so a kiosk reboot doesn't start with a blank chart, then fills in live at high resolution from there.

How fresh is this, exactly? Different pieces update at different speeds, since each comes from a different source polled on its own schedule. The panel display itself re-evaluates roughly every second, but that's just recalculating with whatever data is already cached — the actual freshness ceiling is set by the slowest contributing source for whatever changed. DX Cluster and RBN spots are both live (always-open connections — a new spot appears within about a second of arriving). The SSN/Kp numbers feeding the MUF prediction itself refresh at most every 14 minutes, matching NOAA SWPC's own update cadence — though the computed MUF still drifts continuously between those refreshes, since it also depends on solar elevation at your QTH, which changes every second regardless of when SSN/Kp last updated.

Decision log, for checking whether this is actually reliable. Every time the "best band" pick changes, a full snapshot of that moment — every band's predicted status, computed MUF, per-source evidence counts, and resulting score — is written to a log file on the device, so the decisions themselves can be reviewed later rather than just trusted in the moment. A heartbeat entry is also logged every 5 minutes even when nothing changed, so a quiet, stable stretch is still visible in the record rather than just an absence of entries. The log is plain JSONL (one JSON object per line) at a fixed path on the device, and is also available over HTTP at /api/bestband-log (GET) if you'd rather pull it that way than over SSH/SCP.

Why does FAA WeatherCams open FAA's own page instead of showing images directly in Helioclock?
Two real technical walls, not a design preference. First, there's no public API for this data — the obvious endpoint (api.weathercams.faa.gov) returns "not authorized," and the live image URLs are only computable by a real browser running FAA's own React application; a plain server-side fetch of any page on the site returns just "JavaScript is required to use this application," with no usable data in it. Second, each camera image's URL embeds a server-validated timestamp — guessing or constructing one returns "Access Denied," so there's no way to reliably build "today's image" ourselves even knowing the general URL pattern. Given that, embedding FAA's own live page is both the only reliable option and, arguably, the more defensible one: this app is acting as a browser showing FAA's unmodified page, not fetching and re-hosting their imagery itself. The site list itself (955 sites) doesn't come from a public API either — no API to source it from — so it was extracted once from a real saved page; it's static reference data bundled with the app, not something polled live. NAV Canada operates roughly 225 of the 955 sites shown on FAA's shared portal; those can be excluded with a toggle in the detail view for anyone who'd rather not rely on a second country's aviation authority's content even via embedding.

Will it run on wired or wireless? Does it matter if I switch, or have both connected at the same time?
Helioclock runs on either wired Ethernet or WiFi without any configuration change. The server binds to all network interfaces by default, so it is reachable on whatever IP address your router assigns — whether that is the wired port, the wireless adapter, or both simultaneously. Switching from wired to wireless (or vice versa) while running is fine; there may be a brief pause in data fetches while the network reconnects, but the server will resume on its own. If both are connected at the same time both will work. For kiosk installations wired Ethernet is recommended for stability — WiFi is adequate for casual use but can introduce intermittent fetch delays on a busy 2.4GHz network.

I'm running this on a Raspberry Pi 4. Do I need a heatsink and fan?
Yes to a heatsink, recommended but not required for a fan. The Pi 4 runs a full-resolution canvas at 1080p or 4K continuously, which is a sustained CPU and GPU workload. Without any cooling, the Pi 4 will thermal-throttle after 20–30 minutes — you will see the display stutter and frame rates drop. A passive heatsink case (aluminum shell with no moving parts) is sufficient for most indoor ambient temperatures and eliminates throttling entirely. An active fan is only necessary in a warm equipment rack or enclosure with poor airflow. The Helioclock SD card SKU is tested with a passive heatsink case. If you are using the bare board in a standard plastic case, add at minimum the stick-on copper heatsinks that come with most Pi 4 accessory kits.

My Raspberry Pi 4 has two HDMI outputs. Can Helioclock drive both displays at the same time?
Helioclock drives one display per Pi — the kiosk session uses whichever HDMI port it launches on, and the second port is not used. For additional screens, use the Remote View feature: any TV, monitor, laptop, tablet, or phone on your LAN can open http://helioclock.local/ in a browser for a fully live, independent view — no limit on simultaneous connections. If you specifically need two or more HDMI-connected screens driven from the same Pi, an HDMI splitter/amplifier will mirror the kiosk display to as many screens as the splitter supports, with no additional configuration required.

How many remote browser connections can I make at the same time?
There is no hard-coded connection limit. In practice the bottleneck is the Pi 4's CPU and network bandwidth. Each connected browser receives its own stream of API responses — radar frames, lightning data, NWS alerts, and so on. A Pi 4 comfortably handles 3–5 simultaneous browser connections without noticeable degradation. Beyond that, radar frame fetches and GLM polling from multiple clients can saturate upstream API rate limits before the Pi itself becomes the bottleneck. The SKU4 multi-display server is designed for higher connection counts and includes server-side API fan-out caching so all clients share a single upstream fetch regardless of how many browsers are connected.

Why is there no lightning data for my area?
NOAA GOES-19 GLM covers the Western Hemisphere only — roughly 141°W to 9°E, 54°N to 54°S. If you are outside this footprint (Alaska, Hawaii, Europe, Asia, Africa) the lightning layer will show no data. This is a limitation of the GOES-19 satellite position, not a bug. GLM data also has a ~2-minute latency from the time of a strike to when it appears in the feed.

Why does the radar scope show "LOADING RADAR" or stale data?
On first open the server needs to fetch the current RainViewer tile for your location, which takes 2–4 seconds. If the data appears stuck, check the UPDATED timestamp in the lower-right corner of the scope — it shows how old the current tile is. The scope refreshes every 30 seconds automatically. RainViewer data is typically 2–3 minutes behind real-time. If the timestamp is very old, your server may have lost internet connectivity.

Why is the map completely black at night in some areas?
That is correct behavior. The night side of the map uses NASA Black Marble imagery — actual satellite photography of Earth at night, showing city lights, gas flares, and fishing fleets. Dark areas are genuinely dark: open ocean, wilderness, and sparsely populated regions. It is not a rendering error.

My city clock shows the wrong time, or DST seems off.
Make sure your QTH location is set correctly in Settings — the local time display and DST calculations depend on it. For city clocks added via the city picker, DST is handled automatically using the IANA timezone database. If a clock is one hour off, the most likely cause is a DST transition that occurred after the page loaded — reload the page to pick up the new offset. EU and Southern Hemisphere DST transition dates differ from the US; full EU/SH DST support is on the roadmap.

The display froze and the clocks stopped advancing. What happened?
As of v1.1.810 Helioclock includes an automatic watchdog: if the clock has not ticked for 90 seconds, the page reloads itself. This recovers from any JavaScript stall without requiring manual intervention. If you see the display briefly go dark and reload overnight, that is the watchdog doing its job. If you notice a freeze before the watchdog fires, press Ctrl+Shift+R on the kiosk keyboard to force an immediate hard reload. The most common cause of freezing is memory pressure in the browser after many hours of continuous operation.

Can Helioclock run without an internet connection?
Partially. The base map, solar terminator, city clocks, and all static overlays work entirely offline. Live data feeds — radar, lightning, NWS alerts, DX Cluster, space weather, GOES clouds, satellite passes — require internet access to update. On an offline LAN the display will show the last cached data for each layer until connectivity is restored, then resume updating automatically. The server does not require a persistent connection; intermittent connectivity is handled gracefully.

Is my location data sent to anyone?
No. Your QTH coordinates are stored only in the server's local configuration file on your hardware and are never transmitted to Helioclock servers or any third party. Data source requests (NWS alerts, weather, radar tiles) include your approximate coordinates as query parameters to the respective government and public data sources — the same information any weather app sends — but those requests go directly from your hardware to the data provider, not through any Helioclock intermediary. The optional Operator Honor Roll registration transmits only your callsign, 4-character Maidenhead grid square, software version, and tier — never your name, email, or precise coordinates.