Blue circle light that hovered, flew left and right, then descended.

Was on balcony of apartment talking with my boyfriend when i noticed a bright very blue light.  Normally, i would dismiss as a helicopter but have never seen one with such a blue light before.  
As we talked, i watched as it slowly descended perfectly straight down then hovered still in the sky.  Then it glided straight and perfect to the right about a half fields distance.  Then it glided perfectly straight to the left in the opposite direction.  Then glided on the same perfectly straight path back to the middle and slowly descended perfectly straight down.  It was a perfect cross it traveled now that i think about it.  As far as I've known, there are no known air crafts that can move so perfectly and at such sharp angles.