How to Use It
Put your grid square in, then look along the shaded twilight band from your blue dot. Places that sit on the same band share your sunrise or sunset, and those are the paths most likely to open on 160, 80 and 40 meters.
To plan a contact, type the other station’s callsign or grid. The map draws the path between you, shows their sunrise and sunset, and lists the times in the next 24 hours when you are both on the gray line. “Show on map” slides the map to that time.
Slide “Look ahead” to see where the band will be later today, for example to plan an evening on 80 meters. The band tilts through the year and only runs straight north and south in March and September.
Why it works, in plain words, is on our gray line explainer. This map is worked out in your browser from the time of day. Your location never leaves your browser. A callsign you type in “The other station” is looked up at HamDB or Callook, the same free services our Callsign Lookup uses.