Iridium Flare in Bootes

Iridium is a constellation of more than 70 communications satellites that are continuously circling the Earth. Iridium flares occur when sunlight reflects off an antenna of one of the satellites; they last only a few seconds and look like a slow-moving meteor. These flares can be as bright as magnitude -8, and can easily be seen even from the city! I photographed this magnitude -7 flare of Iridium satellite #36 under the fairly light-polluted skies of suburban Phoenix, Arizona; thin clouds blowing in front of the flare were illuminated by the city lights and a first-quarter moon. The flare was in the constellation of Bootes; the bright star below the flare is delta Bootis.

Iridium flares are much easier to view and photograph than meteors, because they can be accurately predicted! The Heavens Above web site can tell you what flares will be visible from your location. You can pick from a list of major cities, but since Iridium flares are very location-sensitive, enter your exact location in latitude and longitude (preferably within 0.01 degree of latitude and longitude, or about 1 kilometer). The site will tell you exactly when and where to look for each flare, as well as how bright it will appear. One hint: the orbits do change over time, so be sure to download a fresh prediction within a day or two of when you plan to observe. Good luck and good viewing!

Location: suburban Phoenix, Arizona
Date: May 5, 1998
Time: 8:43 p.m. MST
Camera: Olympus OM-1 35mm SLR on fixed tripod
Film: Fuji Provia 1600 slide
Focal length: 200 mm
Aperture: f/5.6
Exposure time: 20 seconds
Scanner: Nikon Coolscan LS-2000