Blue Book document:
"The object was not a balloon, since the speed was too fast. A rawinsonde was released at 1500Z and moved off to the east. The object moved against the wind. The blip size was that of a normal aircraft. The object was not a known aircraft because the altitude was too high. The object was not astronomical as dual radar returns eliminate this. Electronic or visual mirage of meteorological phenomenon is out of the question as the radar set was on high beam, and both would not occur simultaneously in the same place. The sighting occurred above the weather." (See Frame 566)
The following pdf file contains all of the resized Project Blue Book documents below and is now housed on the NICAP site for security reasons.
The original over-sized docs from the Blue Book site are listed below:
Frames 565-576, commencing with