Horizontal close row of 8 light green/lime colored lights

When I opened my back den window to let cooler air in, I saw a perfect horizontal row of 8 bright light/lime green lights to the NW. It was not moving across the sky but was stationary and blinking on/off over and over again in short, regular intervals, the entire row of lights at the exact same time. It definitely gave me the impression that it was one object as it would blink off and quickly return all together. There was no sound. I ran to get my binoculars, returning quickly, but could not see it any more. Minutes later I went to look again, and saw it heading slowly farther N and slightly NE. For more than an hour, every time I checked to see if it was still there, I could see it very slowly moving N, getting smaller as it moved away from where it was when I first saw it. It did not blink on/off as it began to travel N. The only other thing I noticed was that there were soon quite a number of helicopters in the area as though searching for something in a very wide circle. It is usual to spot one police helicopter at times, but never 6+. I had never seen anything like it before.