large triangle object above hudson river

On stony point side of Hudson river at lovett generating station looking towards Indian Point nuke plant across river . Directly between both plants, spanning across the river are 345 kv transmission lines, above these lines approx 500-600 feet above the river was a huge object possibly triangle shaped.It was pivoting in place, but not moving n,s,e, or w. We could tell it was pivoting because all of the lights were moving proportionately , very strange! I dont remember the color of the lights but they were not that bright. this object made no noise. We were approx 1/8-1/4 mile away which was fairly close considering the size of this thing. It was a fairly clear night but other than silouette could not see in detail the object.
This sighting may have been one of many from the so-called "Hudson Valley" sightings of the late 1980's.  Date here in July 1989 apparently is approximate.  PD