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[KT5MR]

Hi all,

If I am understanding the grayline properly, it is the area around the Earth's terminator in which the E and F layers are still relatively highly ionized by the sun, but the D layer is not; basically twilight.

I've learned that propagation is not always nice and neat, but is working a station with grayline propagation generally require both stations to be in twilight, or can one station be in twilight and the other in the range of full sunlight or darkness?

The reason I am asking is that last night I was on JT65 on 20 meters.  A station in French Polynesia popped up and I, unsuccessfully unfortunately, tried to work them.  They faded out rather quickly after 3 am UTC (10 pm local).  JT65 records all signals it hears, so I looked back and noticed that I first started hearing them around 2 am UTC (9 pm local).  During this hour, the station started out weak, became strong, then went weak again and finally faded out completely.

I happened to look at a day/night map and noticed that during this brief window in which I could hear them, French Polynesia was in twilight. 

So I'm unclear....to what extent was my hearing the station due to grayline propagation?  Do both stations have to be in twilight, or does only one need to be in twilight like my French Polynesian station while I was in full darkness?

--Michael / KT5MR

[N3QE]

Some tell me that "true grayline", requires both ends to be in twilight.

That said there can be a real enhancement for many paths, even those not really on the low bands, when just one end or the other is in twilight.

[KB8GAE]

Michael,

This link corresponds to what I have experienced.

http://www.ng3k.com/Misc/n4kgprop.html

Hope it helps.

73's Rich KB8GAE

[W8JX]

Some tell me that "true grayline", requires both ends to be in twilight.

Not true, it just requires the grayline to be in the optimal skip zone for the path between the stations in question.

[KT5MR]

I didn't ever think of it that way, in terms of multi-hop.   This is cool. 

One thing that does drive me crazy when reading about grayline propagation is that many articles aren't clear when they refer to sunrise or sunset.  My sunrise/sunset?  The other stations?  Both of us?  Only one of us?

--Michael / KT5MR

[KS2G]

WORKING THE GRAY LINE
 by Paul Harden, NA5N

http://www.qsl.net/w2vtm/grayline.html

[WA2ISE]

If you have an extra Garmin GPS laying around, you can use it to have it show where the grayline currently is.

Garmin nuvi GPS's have been around just long enough that we end up with extras. Older ones we didn't want to spend the money to update the maps. But you can use it in your shack to get very accurate time zulu. Get a 5V wall wort with a small USB plug and use it to power and charge the GPS. Assuming it can hear the GPS satellites, you can go to a screen with a clock. On the screen that says "Where to" and "view map" pick "tools", then hit the down arrow to get to "world clock". Hit that, and you'll see a clock of your time zone plus digital time of 3 cities. Okay, go back to "tools" and pick "settings" and then "time". hit "12 hour" and then select "UTC". Then go back to world clock, and you'll see time zulu as digits. Now select "World Map" to get a display of where it's daytime, night, and where the grayline currently is. This is a strip of the Earth where propagation is usually good. And you'll still have the time zulu (UTC) displayed. This will work anywhere in the world, great for DXpeditions.

[K7HN]

 I can tell you from my experience with gray line propagation, I’ve had my longest QSO’s during that particular time.

 I live in western Oregon. At sunset my time I have a great signal even using a dipole traveling east word. My farthest curassow has been to the Dominican Republic on SSB running barefoot.  That was about 3,600 miles.

 On the other end of the scale, while I am in total darkness and the transmitting station is at or just passed gray line,  I get tremendous barefoot QSO’s west of me.  They go about twice as far. That’s because I’m only about 40 miles east of the Pacific Ocean.  My farthest QSO on LSB was Saipan at a SOLID 5/9. The receiving station also said (after I asked him to be honest with me on the reception report) that I was a “Strong 5/9.” That was 6,500 miles, most of it over open ocean. Both QSO’s were at 40m.

Gray line is amazing if you’re patient and in luck that someone’s transmitting on a frequency you’re monitoring.  Don’t count out the strong signals either! In my case, Saipan was really strong for about 15 minutes. It’s short lived for sure. But worth the effort.

[AA6YQ]

DXView, a component of the freeware DXLab Suite, can compute and display future gray-line openings between your QTH and a location selected by entering a callsign fragment or by clicking on a world map.

Here's an example computing the next gray-line opening between my QTH near Boston and Thailand, which I need for this year's CQ DX Marathon. The next gray-line opening will start on August 27th at 2259Z (my sunset) and will last for just over 30 minutes. The map below shows the location of the solar terminator halfway through the opening: