High altitude flashing light observedJust after sunset, I was looking casually into the darkening but clear sky--some slight cloud cover (<10%) when I noticed a single light (white) flash from what seemed to be very high altitude. Brightness was equivalent to a evening star/planet and occurred in a 1 second flash. I kept watching and this occurred again after maybe 3 seconds and it appeared the source had moved. It happened again a third time, also a few seconds later. I moved to the outside porch and watched intently in this area for another 10 minutes but saw nothing further. The impression was of some object emitting a powerful flash from a very high altitude.((NUFORC Note: Report is not inconsistent with the flash from a rocket booster tumbling in orbit. That is merely a guess, however. PD))