UFO Sighting in Cheltenham, Pennsylvania on June 17th 2015 – Circular shape with multiple Blinking lights in succession – tube like “Exhaust” tanks in multiples of three

Light Grey Circular shape with multiple Blinking lights in succession Red, Green & White - tube like "Exhaust" tanks in multiples of three lined up Horizontally around the four points of the circular shape - slowly ascended away and at the rate of a Helicopter...Airplanes and Helicopters will only have a couple of blinking lights below, above and on the wings of the craft...this UFO had a succession of three-four lights blinking in sequence Red, Green & then White...the craft seemed to be the back end of a craft (circular) but was extremely large...I watched for approximately 15-20 minutes as it slowly ascended...from what looked like Tree top level ever slowly higher and higher...I tried to figure out or identify what I was seeing, but I have never seen any type of craft such as that...