A friend and myself were camping at a U.S. Forest Service campground along the middle fork of the Boise River in Idaho. The campground was dubbed 'Troutville' and is located approximately 1/3rd of the way to Atlanta on Middle Fork Road from Arrowrock Dam. I'm a big star gazer and amateur astronomer and haven't been away from city lights for a number of years, so I was taking the opportunity to soak in as much as I could. I had already witnessed about 10 satellites in orbit when, at approximately 11 PM (I forgot my watch and my friend forgot the car charger for her cellphone and her battery was kaput, so I had no means of checking the time exactly) while looking at an area of the sky to the northwest around the constellations of Perseus, Cassiopeia and Andromeda, I saw what appeared to me as one of those 'aerial bombs' that go off at firework shows (the ones that are just a mere flash of white light but produce a huge concussion). I focused on the spot that the flash happened at and began to wonder what would make such a bright flash. I asked my friend if she saw it as well, and she had. About 20 seconds later it happened again in what appeared to be the very same spot. My friend was no longer looking at that spot and I informed her that it had happened again and we began to discuss scenarios that might explain the phenomenon, from a new pulsar to a ground based defense laser firing at a target satellite to sunlight reflecting off of individual solar panels on the ISS and countless other things that might explain it. Even though I witnessed a massive 'black boomerang' in 1994 that was undoubtedly an E.T., I'm not the type to assume that every anomaly in the sky is a visitor from another planet. I decided that if I saw it any more times that I would time it to see whether it was reoccurring at precise intervals. When it happened the third time I started counting out loud "One thousand one. One thousand two, etc", and I also moved so that the top of a pine tree was horizontal to where it happened at, this way I could tell if it was moving, if at all. When I counted out to 20 it happened again but I couldn't be sure if it had moved any. When the next flash occurred it was at the 18 count, and I could tell that it was indeed moving, albeit very slowly, from the region of the constellation of Andromeda towards Perseus. The next time it happened I had counted all the way to 22 and it had become noticeably dim, but was still rather bright. By means of averaging my inaccurate counts I figure it was happening every 20 seconds exactly. It happened 3 more times, and each time it's luminosity was markedly diminished from the time before, such that I couldn't tell if it continued on and reached a range where the light had become insignificant to my perception, or simply fizzled out. The entire event took approximately 3 minutes, and the object only traversed an area of sky which I can only describe as a measure of 'about the distance between my thumb and index finger appear to be when my arm is fully outstretched'. When I got back to Boise I started doing research online to see if what I had witnessed was indeed a known phenomena, but every search parameter I've tried has turned up nothing, so I figured I'd file it here. If this is something that's already been researched and explained by MUFON, could you send me an email at the address that I've included with this form to let me know what it was? Thanks a bunch.