[SADXA] RESEND - VK0EK Heard Island Propagation Question - from Bill W7EXG

[W7EXG (Bill)]

Hi Ray, 

I think you should get a prize too!! You were the 1st on Reflector to
comment on VK0EK RF on 3/24. You said: 

"Interesting propagation.  I heard nothing from VK0EK until half an hour
before sunrise.  He peaked 579 around SR, then faded and was gone  30-40
minutes after.  Quite a grayline." 73 Ray W2RS

That comment woke everyone up, and actually got me thinking about Gray-line.
As you may know, I launched a study during the Heard Island Propagation
time, gathering as much propagation data as possible. Data was mainly from
my own observations with Yagi (7MHz and up), but also from others who
reported on the Reflector. 20 observations were defined in terms of
bearings, AM / PM times, Time windows, and Dates. I presented this data at
the July 21st SADXA meeting. Don't know if you were there?

I noted your above comment as an observation in the data, but guessed at the
LP bearing. I did NOT know you actually worked Heard that AM.

NOW -- for the answer to your question:

On 3/24, TUCSON SUNRISE was 6:22am local, 
	   HEARD SUNSET was 6:06pm Local 
You can see from this data, TRUE Gray-line Propagation starts at 6:06 Local,
and ends 6:22am Local, defining a 16 min time window, where propagation was
completely in the Twilight Region. HOWEVER -- THIS ASSUMES THE ANGLE OF THE
GREAT CIRCLE PATH AND ANGLE OF THE TERMINATOR WAS THE SAME. Reality was
different.  

Since your 30m contact was at 6:05am Tucson, it was also 6:05pm at HEARD!!  

This means your Contact was 1 min. before HEARD ISLAND SUNSET!! 

SORRY -- You missed the Possible TRUE Gray-line propagation by 1 Min!!
Sounds like MY LUCK!!

You could argue the SR/SS Time Calendars are off by at least 1 min., which
is a reasonable argument, but there is another issue discussed below.  

The Sunrise Terminator angle was -2 degrees. The Great Circle Path was
either 185.4 deg short path, or + 5.4 deg. long path. 

Our data has shown, there was NO SHORT PATH AM PROPAGATION, and the reason
was due to a VERY LOW MUF near HEARTD in the Short Path during the AM. So,
your signal was most likely a long path signal.. This means your RF was
actually diverging from the Terminator at a 7.4 degree angle, towards the
North DAY region, almost all the way around earth to Heard Island. Your RF
would have been about 1545 mi away from the terminator (DAY side)at half way
around the world. 

Thus, my conclusion is -- this was NOT TRUE Gray-line Propagation. 

The lesson learned here, is that both stations could actually be IN THE
GRAYLINE, but if there is an angular difference between the Terminator and
the Great Circle path.. the signal may wander OUTSIDE of the Gray-line
during its propagation. The Gray-line Purists in the Group would say NO
GRAY-LINE propagation. 

I would refer to this propagation path as Terminator Enhanced Propagation. 

All of this will be covered in my PART 2 SADXA presentation on Oct 20th. 

Ray, Thanks so much for your response. I hope this explanation has value to
you and some members of the group.  

Best 73s, 

Bill W7EXG

-----Original Message-----
From: SADXA [mailto:sadxa-bounces at mailman.qth.net] On Behalf Of W2RS - Ray
Soifer via SADXA
Sent: Sunday, September 11, 2016 7:42 AM
To: sadxa at mailman.qth.net
Cc: rsoifer1 at aol.com
Subject: Re: [SADXA] RESEND - VK0EK Heard Island Propagation Question - from
Bill W7EXG

Bill,


I worked VK0EK on 30 CW at 1305 on March 24th.  Does that count as grayline?


73 Ray W2RS (Green Valley)



-----Original Message-----
From: W7EXG (Bill) <W7EXG at q.com>
To: 'Southern AZ DX Association E-Mail Reflector' <sadxa at mailman.qth.net>
Sent: Sat, Sep 10, 2016 8:19 pm
Subject: Re: [SADXA] RESEND - VK0EK Heard Island Propagation Question - from
Bill W7EXG

Thanks Wes.

With you in mind, I developed a very simple formula criteria and graphic
defining TRUE Gray-line Propagation window for any two stations adjacent to
the terminator at opposite time zones.   (TRUE meaning ALL propagation
within the Gray-line Twilight Zone) This will be shown in my October
presentation to the SADXA group. It will clearly show that NONE of the
Tucson PM propagation to Heard was TRUE Gray-line propagation. However, the
data will also show that in the morning, prior to Tucson Sunrise, TRUE
Gray-line propagation conditions existed, with the time window being a
function of the date. 

This will clearly differentiate the Gray-line Propagation as a sub-set of
Terminator Enhanced Propagation. For Heard, Terminator Enhanced Propagation
occurred mostly after Sunrise and always after Sunset Tucson Time. 

Your RTTY observation was more of a Terminator Enhanced Propagation, due to
lower D and lower E conditions and HIGH MUF less than 1 hour AFTER Tucson
Sunset, and Low D, Low E and increasing MUF about 1 hour AFTER Heard
Sunrise.   

Jerry, W6XI, may have the ONLY TRUE Gray-line QSO for the group. His 13:02
30m contact with HEARD on 4/5 was completely within the Twilight Region and
was only 4 min. before Tucson Sunrise. Hi Hi. W6XI may WIN "The Great Heard
Island TRUE Gray-line Propagation Prize"! Or GHITGLPP for short!! I am
looking for someone who will share this VERY coveted Prize with Jerry. 

73s, 

Bill W7EXG
 

-----Original Message-----
From: SADXA [mailto:sadxa-bounces at mailman.qth.net] On Behalf Of Wes Stewart
Sent: Saturday, September 10, 2016 5:39 PM
To: sadxa at mailman.qth.net
Subject: Re: [SADXA] RESEND - VK0EK Heard Island Propagation Question - from
Bill W7EXG

Not me.

BTW, I did log an RTTY QSO on 30-meters at 0237Z our time but sadly they
logged 
N6WS.

On 9/10/2016 3:16 PM, W7EXG (Bill) wrote:
> SORRY - COULD BE CONFUSION
> 	- LOOKING FOR VK0EK CONTACTS 30 min before Sunrise.
>
> QUESTION:
> 	For VK0EK Heard Island Enthusiasts
> FROM:
> 	Bill W7EXG
>
> RE: Heard Island Gray-line Propagation
>
> Did anyone work Heard Island [VK0EK] in the Morning within 30 minutes
> BEFORE Tucson Sunrise?
>
> I did NOT see anyone suggest a VK0EK contact on Reflector during this
time.
>
> If so, could you please provide me with your contact data?
>
> I am working on the October SADXA Tucson/Heard Island propagation
> Presentation - PART-2, and this data would have value.
>
> PS: Jerry [W6XI] privately reported a 30m contact 4 Min. before Sunrise on
> 4/5 UTC.
>
> Best 73s, and THANKS!
>
> Bill W7EXG
>
>

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