Crowd of many witness flying saucer during Forth of July fireworks show in 1976

My family was at a 4th of July fireworks show in Ausable Forks in 1976.  There were at least 50 people in our group of people (in the area we were at) who were witness to what we say.
During the fireworks show people started talking and pointing.  My father told me where to look and I saw a round shaped flying saucer.  It was quite high in altitude.  The total time we watched it was probably about fifteen minutes.
We know it was not a shooting star, plane, helicopter, etc., the object moved quickly across the sky and stopped instantly (super-fast speed to a full stop), it hovered for some time and then started moving again, it made a 90 degree turn in mid-flight without losing any speed and continued its flight. 
Then it stopped again and after a short time it just “warped out” (?)  I don’t know how to explain it any better; it just instantly zipped off into outer space.
The object was circular/round in shape, it was white/light blue (probably very light blue), it had no blinking lights (no lights like a plane might have, etc.), it was quite high, but I cannot estimate the height because I have no clue how large it was (it could have been a smaller ship closer to us or a massive ship further away).
The speed and the instant stop, instant warping away and turning 90 degrees instantly in mid-flight really let everyone know it wasn’t anything our civilization was capable of doing (this was almost 40 years ago, and we still don’t have the ability to make a turn like that).
The crowd of people was quite large, and a lot of people saw it, but I remember my father telling me to not talk about it after it happened.  He clearly told me to never forget it because I would likely never see anything like it again, but was told to not tell people we saw it (probably a fear of being ridiculed?).
I am not sure if it was reported in the paper or if police reports might still be available from that far back, but I have no doubt we saw a ship that was not from our Earth.
You may contact me if there is any information I can give you that I did not make clear in this report, but I do not want my name displayed publicly.
Thank you!