After reading the reports that the previous Pegasus was seen from Tucson, AZ, I decided to look for this one. I saw it very low on the horizon nearly due West from my street. It looked like a comet with a very bright and diffuse tail. It moved toward the South and gained altitude, and the "tail" got larger and spread out more. After maybe 10 or 15 seconds it had risen to about 10 degrees elevation and then it stopped advancing, which I believe was probably the end of the second stage burn. I waited to see if I could see the third stage ignition, but didn't see anything more. What really amazed me was how quickly the illuminated plume appeared to spread since it was at least 700km away from me. In a very few seconds the plume spread from a wedge-shape like a comet tail to a big glowing cloud. I don't think that I would have seen the Pegasus had the vehicle and its exhaust plume not been illuminated sunlight -- especially since all of the air traffic from Southern California to Phoenix approaches from due West of my house and there are nearly always a cluster of airliners with landing lights on in that direction. The brightness and the size of the moving wedge-shaped plume made it really stand out. I'd be curious to read descriptions of what the launch looked like from other vantage points. I heard that at least near the coast it was too foggy to see it from LA. - John Jordan Phoenix, AZ Lat 33deg 27' 12" N, Long 112deg 4' 28" W