a bright light followed a slow zigzag path from the horizon to the zenith then made a right angle turn

A group of campers went on an overnight trail ride and camped by a river near the Brentwood riding camp in western New York.  Apparently the counselors had stayed up late chatting. Sometime after midnight they came around and woke us up to see what they hadd spotted in the sky.
We watched a shaky spot of light that hung just over the southern horizon in the middle of a circle stars.  After about 10 minutes the light began to make its way towards the zenith, but it didn't travel in a straight line and it moved relatively slowly.  It zigzagged from side to side as it moved upwards. Taking roughly 15 minutes to reach the zenith.  It then made a right angle turn and headed down towards the western horizon moving in the same back and forth manner.
After about 5 minutes it changed course and in a straight lined zoomed away from the planet.  It was gone in seconds.
The night was absolutely clear with no moon and the sky was full of stars.  It was bright enough that we could see each other in the glow of starlight.