Monday, July 28, 2014I began watching the sky for an Iridium satellite flare (listed as Iridium 84 on my smart phone app), which was predicted to peak at 21:39:17 at elevation 63 degrees and azimuth 97 degrees at my home location at approximately 45 seconds before the flare was to peak (I had been alerted by a 1 min alarm on my app and walked outside). At almost the same time that the Iridium satellite became visible moving north to south, I observed another object, moving approximately from 300 degrees to 120 degrees, at an elevation similar to that of the Iridium satellite. This object was a single, large, white pinpoint, quite bright, moving at a constant speed. It moved across the sky much faster than the satellite, but much slower than any meteor I have seen. It covered approximately 60 degrees of sky before fading from view in the light pollution or passing into the Earth's shadow at an approximate angle of elevation of 40 degrees. The elapsed time of observation was approximately 10 seconds, beginning approximately 10 degrees from zenith, crossing at or near zenith, and fading. There was no sound, no appearance of a trail of any kind, and no indication of a debris trail. Sky condition was very slight haze, sufficient to obscure dim stars, but bright stars were visible. Light pollution to the east of my location fading at approximately 40 degrees elevation. Sunset at my location was at 20:51; EECT 21:11, EENT 21:43, EEAT 22:10 (from a smart phone app). Moonset at my location was at 21:43 (according to GPS). Moon phase was two days past new.This object was unlike any meteor I have seen. It covered the sky much too fast to have been any aircraft that I am familiar with. It had disappeared just prior to the Iridium satellite flare peak. The Iridium satellite was predicted to reach a magnitude of -8.5. The unidentified object was of constant magnitude somewhat less than that, although still bright, I estimate it roughly at magnitude -4.0.At the time of the observation, the sun angle was still such that the Iridium 84 satellite was illuminated by the sun; if the unidentified object was illuminated by the sun, it had to be at an altitude similar to that of Iridium 84. I could not tell if it was self-illuminated. I have never seen anything comparable to this unidentified object. The speed with which it covered approximately 60 degrees of arc across the sky was incompatible with any object that I have previously observed; too fast to be a satellite or aircraft, too slow for a meteor or space junk. There was no variation in magnitude and no visible signs of trailing debris. There was no sound of propulsion or sonic shock. It was inconsistent with any of those phenomena from my prior observations. I have been observing the sky for over 50 years. I regularly observe passes of the International Space Station and other visible satellites. I regularly observe meteor showers. I consider myself an extraordinarily qualified observer, having experience in civilian aviation, military operations, scientific data collection, and field surveying.