The April 28, 1955, Dahlgren, Va., case is the planet Venus accidentally caught by telescope theodolite in daytime but could not be seen without the telescope when the two Naval Proving Ground aerographer (weather) observers looked with the naked eye -- just as we would expect from a bright Venus in daylight, invisible to the naked eye and needing optics to see.  It was a white pinpoint of light even as viewed in the 20x telescope.  The Navy weather observers alerted the local air traffic radar site which thought they got the target but there is basically no data on it and the 4602nd AISS and BB didn't investigate to find out the radar data.  

This case was never a BB Unknown and was only in my list because McDonald was interested in it (and probably explained it and filed it).  The original observers thought it might be a Skyhook balloon not a UFO or a flying saucer but evidently reported it out of an abundance of caution, or else those agencies and superiors they notified did the reporting.  The initial observer, petty officer William A. Conlon, was tracking a pibal pilot weather balloon when he apparently spotted Venus in the theodolite (no one asked how this happened, it has to be inferred). 

The 4602nd AISS "investigated" poorly, did not correct grotesque typo errors in the TWX report, and the AISS Commander Col White adopted the Navy Fleet Weather Central's ridiculous explanation that the object seen for 1 hour 56 minutes, from 2:20 to 4:16 PM EDT, was the 7-foot weather balloon launched from Norfolk naval base over 100 miles to the south some 4 hours earlier.  The Norfolk weather balloon was tracked for 33 minutes from 10:03 to 10:36 AM EDT, some 4 hours before the 2:20-4:16 PM Dahlgren sighting.  Tracking was "terminated" most likely by the balloon bursting when the Norfolk balloon reached about 45,774 feet about 5 miles to the W of Norfolk and over 100 miles from Dahlgren.  This balloon is a ridiculous "explanation" -- only to be surpassed by BB soon after. 

BB was stupider because it claimed it was Jupiter, which BB incompetently asserted was because "Jupiter in approximate position" of the object.  No it wasn't! 

The teletype report had teletype errors and the 240 to 259 degree bearing azimuth angles the object moved from during the sighting (roughly SW to W) got printed as "40 and "59 degrees, but two lines farther down on the TWX an intermediate tracking gave a 245 deg azimuth and a case narrative clearly stated the object was in the SW moving slowly to the W (West), so BB had no excuse for screwing this up. 

Venus was at 242 degs azimuth at the beginning of the sighting and 257 degs at the last track reported, near the end of the sighting.  Jupiter moved from 89 to 103 degs, in the E (East), not even close even to the typoed mistaken angles, and in the opposite side of the sky from the theodolite tracking of (Venus) in the W.  Small calibration errors in grounding the theodolite account for the slight angle differences. 

The elevation angles also fit Venus and totally contradict Jupiter.  The Navy theodolite tracked the object from 31.8 degs to 19.8 degs elevation moving downwards.  Venus also moved downwards towards setting, from 31.4 to 16.8 degs elevation.  Jupiter moved upwards from 36.3 to 51.9 degs elevation, not even close.