no light and moved very slowly

I was looking outside of my window at work and saw a light blue metallic blimp shaped thing, moving very slowly.  It was very close to my window, 4 flights up and much smaller than a blimp.  On the bottom, near the back, it had a stick, kind of diagonal, and small.  
This was in Manhattan where we never see anything.  I never found out what it was, do you have any idea.  I don't know the date, but it was 6 or 7 years ago.  Thank you.