World Map
The map is the heart of OpenHamClock — a live, interactive globe that brings together DX spots, activations, satellite positions, propagation overlays, and real-world events in one view.
Overview
The world map is built on Leaflet.js and sits at the centre of the Modern and Classic layouts. It is not just a background image — everything on it is live and interactive. Click any marker to open a popup with details and, where relevant, a button to tune your radio directly to that frequency.
The map automatically centres on your home grid square at startup. It updates continuously: DX spot markers refresh every 5 seconds, satellite positions every 5 seconds, POTA/SOTA activators every 60 seconds.
What's on the Map
Your home QTH
A home marker (🏠) marks your grid square centre at all times. All great-circle paths are drawn from this point.
DX spot markers
Each active DX spot places a small coloured dot on the map at the DX station's approximate DXCC entity location. Dots are colour-coded by band — the same colour scheme used in the DX Cluster panel:
| Colour | Band |
|---|---|
| Red | 160 m |
| Orange | 80 m |
| Yellow | 40 m |
| Green | 20 m |
| Blue | 17 m / 15 m |
| Purple | 12 m / 10 m |
| Pink | 6 m and above (VHF+) |
Great-circle paths
When you click a DX spot — either in the DX Cluster panel or directly on the map — OpenHamClock draws the great-circle path from your QTH to the DX station as a curved line on the globe. This is the actual shortest-distance radio propagation path, not a straight line on a flat map.
The bearing (in degrees true) and distance (in km or miles, depending on your units setting) are shown in the DX Location panel. This is exactly the heading you would point a beam antenna.
POTA / SOTA / WWFF / WWBOTA markers
Active park and summit activators appear as distinct icons on the map. Click any one to see the callsign, park/summit reference, and current frequency. If rig control is configured, a Tune button tunes your radio immediately. See POTA / SOTA for full details.
Satellite positions
Active ham satellites move in real time across the map with their ground track projected ahead. A shaded ellipse shows the current footprint — the area on Earth that can currently hear or work the satellite. See Satellites for full details.
Day / Night Terminator
The map shows the current boundary between day and night as a soft gradient overlay. This is more than aesthetics — it is directly useful for HF propagation:
- Grey-line propagation — the terminator edge (grey line) is a zone of unusually strong long-distance propagation, especially on 80 m and 40 m at dawn and dusk.
- Night-side conditions — lower frequency bands (160 m, 80 m, 40 m) become quieter and longer-range after dark due to the disappearance of the D-layer absorption.
- Day-side conditions — higher bands (20 m, 17 m, 15 m, 10 m) open up as solar UV ionises the F-layer.
The terminator moves continuously — you can literally watch the grey line sweep across the map as the Earth rotates. This is one of the most genuinely useful features for timing DX contacts.
Map Layers
OpenHamClock has a plugin-based layer system. Layers are overlaid on top of the base map and can be toggled individually from the Layers button (stack icon) in the map toolbar.
| Layer | Source | What it shows | Refresh |
|---|---|---|---|
| Aurora | NOAA OVATION | Predicted aurora oval — where the northern/southern lights are active right now. Colour-coded by intensity. | 30 min |
| Earthquakes | USGS | Recent earthquakes (M2.5+) as circles sized by magnitude. | 15 min |
| Precipitation | Open-Meteo | Current rain and snow radar overlay. | 15 min |
| Lightning | Blitzortung | Recent lightning strikes as small flash markers. | 5 min |
| Wildfires | NASA FIRMS | Active wildfire detections from satellite thermal imaging. | 1 hr |
| Winlink Gateways | Winlink.org | Active Winlink radio email gateway stations. | 1 hr |
| Active Users | Internal | Grid squares of other users currently connected to your OpenHamClock instance. | Real-time |
| VOACAP | VOACAP Online | HF propagation reliability predictions for the selected band and hour. | On demand |
The Aurora layer is particularly useful for VHF/UHF operators chasing aurora scatter propagation. When the aurora oval extends to your latitude, aurora backscatter contacts become possible on 2 m and 70 cm. High K-index in the Space Weather panel is your first alert; the Aurora layer shows the actual footprint.
Map Controls
Toolbar buttons
Clicking markers
Clicking any marker on the map opens a popup with details specific to that marker type:
- DX spot — callsign, frequency, mode, band, spotter, and a Tune button (if rig control is enabled).
- POTA/SOTA marker — callsign, park/summit reference and name, frequency, and a Tune button.
- Satellite — satellite name, altitude, range, Doppler shift, and next visible pass time.
- APRS station — callsign, grid, last heard time, speed/altitude (if reported).
Configuring What the Map Shows
Open Settings → Map in the browser to configure:
- Show DX paths — toggle great-circle lines on/off (useful if the map feels cluttered).
- Show DX markers — toggle spot dots on/off independently from path lines.
- Show POTA / SOTA / WWFF / WWBOTA markers — toggle each programme independently.
- Show satellite tracks — toggle ground tracks and footprints.
- DX path duration — how long a path stays drawn after the spot ages (in minutes).
- Map projection — Mercator (default) or Azimuthal Equidistant (your QTH at centre, great circles appear as straight lines).
Also called a "ham radio polar map", this projection places your QTH at the dead centre of the map. Every straight line drawn from the centre is a true great-circle bearing — exactly where to point your beam. Many experienced DXers prefer this view for antenna aiming. Switch to it in Settings → Map → Projection.