V-shaped formation on Vassar College campus

The month and the time listed are approximate.  I was walking across the Vassar College campus from my residence, Davison Hall, to a music rehearsal in the Main Building.
 I first saw the V-shape formation of lights as I was walking near the Strong residence hall toward the Main Building.  It was nighttime and dark outside.  I'm guessing it was between 8pm and 9pm, possibly later.  It was a very clear night.  I just happened to look up and see a V-shape of white lights moving slowly and silently across the sky in formation.  There must have been at least 9 or 10 lights total.  I'm guessing they were about half a mile up, maybe less, maybe more.  I remember trying to tick off the possibilities and really coming up blank as to what I was seeing.  Birds?  No, the shapes were moving too slowly and precisely, and they were lit up.  Planes?  No, there was no noise and no other light.  Helicopters?   Again, not enough noise and lights, and the formation and the movement was too slow and precise.   I thought perhaps it was a military exercise of some sort.  I did not see a wedge shape above the lights or anything to indicate that they were attached to a! larger craft.  They seemed separate, but all moving at the exact same rate of speed.  Some of the lights would "trade places" from one side of the formation to the other and then continue as before, which struck me as very odd.  When this movement occurred, the lights moved at the exact same rate of speed as when flying in the V-shape formation.  The lights continued moving over the Main Building and disappeared from view within about a minute.  There were other witnesses - I estimate that there were at least five other students looking up at the lights.  Some of them commented out loud about what they were seeing, standing in the street in front of the Strong residence hall.
 After doing some research, I believe that what I witnessed was part of the "Hudson Valley" wave of sightings in the 1980s, as described and illustrated recently in Leslie Kean's book, UFOs.
Witness indicates that the date of the sighting is approximate.  PD