Status OK QTH — Click DX point
Now
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DX readout
Click QTH, then click map to set
Bands
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DX Cluster
OFF
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IDLE • --:--:--Z
0 spots • 0 dropped
Configure a DX feed in Settings → DX Cluster JSON feed URL.
No DX Cluster feed configured
Settings
Everything here is local to this browser.
TX semantics: who heard the target station (blue dots with arcs).
RX semantics: what the target station heard (green dots with arcs).
If you leave this empty, GARC HAM Clock automatically fetches fresh TLE data from NORAD/Celestrak on startup (ISS, NOAA 19, AO-91). Data is cached for 24 hours. Manual TLE entry overrides auto-fetch.
Space weather pulls from NOAA SWPC JSON endpoints when available. Satellite positions are computed locally using satellite.js. If a fetch is blocked, you’ll still get a working clock and local sat propagation using your last-known or built-in data.
Help
What this is: a modern single-file HAM clock with a map, greyline, space weather, satellite tracking and pass prediction, and fast DX bearing/distance.
Basic Usage:
  • Setting a DX point: First click the QTH spot to activate, then click any point on the map to set a DX location and draw a great-circle line.
  • Sat list: toggle satellites on/off. Pass table shows next passes within the chosen horizon.
  • DX Cluster: in Settings, paste a CORS-allowed JSON endpoint returning spots with lat/lon or grid to plot on the map and feed the bottom ticker.
  • Space weather is intentionally "calm UI": it gives signal without screaming at you.
Configuration:
  • QTH Location (Your Home Location): By default, the clock uses K4JMC's location. This can ONLY be changed in Settings by entering your lat/lon coordinates directly.
  • Display Callsign: Default is KQ4UZQ. Change this in Settings to your callsign.
  • DX Cluster Callsign: Default is W1AW (ARRL's callsign - almost always on the air, providing plentiful observable data). To change:
    • In Settings, find the DX Cluster URL field
    • Replace "W1AW" in the URL with your preferred callsign
    • Click Save
Technical Notes:
  • This uses heuristic propagation data, not VOACAP data.
  • Tip: If the world map won't load, your browser blocked cross-site fetch. The clock still works; the map will show a placeholder ocean until it can fetch TopoJSON.
How Prop is computed
Inputs: F10.7 (solar flux), Kp/A (geomagnetic), plus a simple day/night check at QTH.
  • F10.7 comes from NOAA/SWPC (when CORS allows). Higher usually helps higher HF bands.
  • Kp/A comes from NOAA/SWPC. Higher usually hurts HF (absorption/auroral).
  • MUF(11m) here is a proxy derived from F10.7 — not VOACAP.
  • Band outlook is a heuristic score using F10.7, Kp, and night/day at your QTH.
Note: If a source is blocked by CORS, values may show "—" or use seeded sidebar values.