and yet it does not stop us...this from an article...
"Years ago I discovered the unexpected possibilities of city observing after moving into downtown New Haven, Connecticut. I assumed that skywatching would cease to be part of my life. But our garret apartment had a plastic bubble skylight over the kitchen sink, and one night, just for laughs, I tried looking through it with 7×50 binoculars. Amazingly, I could make out some stars.
Observing anything under these conditions seemed so remarkable that I did some experimenting. I arranged a way to stand on a stool with my head in the bubble surrounded by light shields. Using a variable-star chart for Mira published in Sky & Telescope, I discovered that my limiting magnitude with the binoculars was as faint as magnitude 8.6. I even spotted Mira near its minimum light.
Star images were distorted by the plastic bubble, it was true, but they were there. "
http://www.astronomer.proboards.com/...nt&thread=3200