Testable theory! Ish.
Three lines originate from the centre of the Circle. Consider them as hands of a clock.
The bottom right line is a second hand.
The lower and longer of the two lines in the bottom left is the minute hand.
The upper and shorter of the two lines in the bottom left is the hour hand.
You get a clock reading 8:35 and 23 seconds.
This gives you 210 35 23, or (I think) -149.4103.
This could be half of the answer. Not sure where the other half might be, though don't most of the barnacles on Merope 5c line up?
Why this might be nothing
Much has been said about how the message ought to not rely on any human construct, and an analogue clock is definitely a human construct. This *might* not matter given previous uses of Morse code and the suggestion that we have been observed and recorded for some time.
It's degrees minutes seconds, not hours minutes seconds.
Why it might be something
That bit in Close Encounters.
http://i.imgur.com/uJDuNfR.jpg