☰ HF Propagation menu

Sunrise, Sunset and Gray Line by Grid Locator

Enter a Maidenhead grid locator or coordinates to get sunrise, sunset, day length and the gray line DX windows, in UTC, for any date.

Grid locator (for example JN34 or JN34ab)

Latitude

Longitude

Date (UTC)

Your position stays in your browser and is never sent anywhere.

How to use the gray line windows

The gray line is the twilight zone along the day/night terminator. Around your sunrise and sunset, absorption on the low bands drops and signals travel unusually far, especially towards stations that are also in twilight. The tool shows a window of 30 minutes before and after each event, which is a good rule of thumb for 160, 80, 40 and 30 metres.

Run the tool for your own locator and for the station you want to work: when your windows overlap, or when the terminator connects both points, try the low bands. To see the terminator right now, open the live gray line map. Background: gray line propagation guide.

Accuracy

Times are computed with the standard NOAA solar position equations for the geometric sunrise and sunset (sun centre 0.833° below the horizon) and are accurate to a minute or two. Near the polar circles the sun may not rise or set on a given day; the tool tells you when that happens.

Data: NOAA Space Weather Prediction Center, NASA SDO. Band conditions are estimates computed by Map For HAM and are indicative only. Methodology and credits · Data feeds · Widgets