what are iridium flares, and where are they visible?
They are flashes of sunlight from Iridium (satphone) sattelites. Pretty bright 2-10 second flashes.
From this page (cool stuff!) http://www.heavens-above.com/?lat=34.065009&lng=-118.44258&loc=UCLA&TZ=PST
I found the link for all iridium flares in the next 7 days (note times are PDT) http://www.heavens-above.com/iridium.asp?Dur=7&lat=34.065009&lng=-118.44258&loc=UCLA&alt=0&tz=PST