As Herouni and his team catalogued the stones, they found one that was different from the rest.  Herouni believes it is the key stone Parsamian was looking for.  "All the stones with apertures point to the horizon or lunar positions in the night sky," he says.  "All, that is, but one."

"While other sight holes pointed to the horizon, this one had an aperture that bent in the center and pointed directly up.  You couldn't see anything looking through that aperture, but if you put something shiny at the bend, something like a polished metal or obsidian, you could look through the hole to a zenith point straight above you.  It was a periscope."  

Herouni excitedly began to make calculations from this unique stone.  Figuring the ancients looked at specific star or constellation through the periscope, he knew he had the key Parsamian was looking for to be able to date the site.  

"The chances of something like that occurring are very small," Herouni said.  "Mathematically I was certain it would lead to one star or group of stars in the sky, and then we would have our date."  

Herouni was able to discount the sun or moon, since they do not cross the zenith point above the stone at that latitude.  At the same time, because of the tilting axis of the earth as it rotates around the sun, the stars change their apparent position in the night sky, something Herouni calls a "delivered rotation to the elliptical plane by 23 degrees, with a conical precision of 26,000 years,"   he knew that what appeared at the zenith could only be a star or stars.  Figuring that even with a polished object as a reflective mirror, the ancients would not have been able to observe any distant stars, Herouni chose to study the brightest stars in the North sky for his calculations.   

Using the same method Parsamian had published in her study on Metsamor,  Herouni took the latitude of the site, five of the brightest stars in the North sky, and compared them with a stellar calendar showing the stars ascendant in Sissian region during different epochs of time.  

"The probability of one of these stars crossing the zenith at that point was very low.  I expected to find at most one star, or one group of stars."

What shocked Herouni when he completed his calculations was that he not one star at the zenith above the stone, he found two.  "The star calendar showed there was a 100% probability of the stone pointing to two stars," Herouni said, "each at different times. The chances of it actually pointing to two stars is infinitesimal."

The two stars are Arktur and Capella.  

"The interesting thing is that Arktur was ascendant at the time the old or "main" style Armenian calendar began (2492 BCE).  Now this would make the site a few hundred years younger then that at Metsamor, but I believed it had to be older, for several reasons, not the least of which is that by the time of Metsamor, the astronomers were already drawing star positions and geometric figures on stone.  It looks like they were mapping the night sky on their observatory site.  But we have found no inscriptions at the Sissian site.  There had to be advancements in the culture to reach Metsamor's sophisticated level."