Scientific Study of Unidentified Flying Objects (the Condon Report, complete, three volumes)

one - "round," "the size of a quarter" (distance not specified), "white
and blue flickering light," a rather good descriptior of a scintillating
star. There was a second magnitude star at precisely the correct
azimuth (190°) at the time, although the elevation angle would have
been only about 1° or so. A sharp temperature inversion, with mist
trapped below it, could have easily produced the effect of larger size
as \\'('11 as increased the apparent elevation angle by about 1 0 • Even
trained observers consistently over-estimate the elevation angle of
objt'cts near the horizon, as in the "moon illusion" (the apparent in-
crease in size of the rising moon).
When "last seen," at about 0150 LST, ~:le object was reported to
be about 20 0 elevation and 170 0 azimuth. At that time another bright
star (0.7 magnitude fainter than the first one) was located at about
172 0
azimutJ and about 10 0
elevation, values commensurate with the
apparent visual position (agaill, assuming over-estimate of elevation
angle) Near the hori zan these were the only two stars of third mag-
nitude or greater in that part of the sky at that time.
TIle description of the radar targets, weak, erratic hlips,
together with the reported formation of a low-level fog (that hin-
dered visual observations after 0150 LST) , suggests the presence of
a shallow temperature inversion-humidity trap that was producing
AP echoes on the radar set. The UFO l'eport states that temperature
inversions \~ere "prevalent" in the area.
In sununary, this UFO incident appears to have been caused by
radar AP echoes and associated visual star sightings, both observed
at small angles through a surface temr~rature inversion-humidity
trap layer.
1()3~._ (yuH of ~1cxico, off Louisiana coast (28 0
N 92° \'I),
(1 llec"?;'lber 1952. ()S2S-05:~5 LST (1125 GMT). Weather: cleaT, dry,
lil':ht winds, visibility excellent, full moon. '111e radio refractivity
220
one - "round," "the size of u quarter" (distance not specified), "",hite
and blue flickering light," a -cather good descriptior of a scintillating
star. There was a second magnitude star at precisely the correct
aZimuth (190°) at the time, although the elevation a:lg1e would have
been only about 1° or so. A sharp temperature inversion, with mist
trapped b ... low it, could have easily produced the effect of larger size
as well as increased the apparent elevation angle by about 1 0. Even
trained observers consistently over-estimate the elevation angle of
ob j ects nea r the hori zon, as in the "moon i Ilus ion" (the apparent in-
crei-lse in size of the rising moon).
When "last seen," at about 0150 LST, t:lC object was reported to
be about 20° elevation and 170· azjmuth. At that time another bright
star (0.7 magnitude fainter than the first one) was located at about
172° azimuU and about 10° elevation, values commensurate with the
apparent visual positiun (again, assuming over-estimate of elevation
angle) Near the hori zon -::hese I-Icre the only two stars of third mag-
nitude or greater in that part of the sky at that time.
TIle description of the radar targets, weak, erratic hlips,
together with the reported formation of a low-level fog (~hat hin-
dered visual observations after 0150 LST) , suggests the presence of
a shallow temperature inversion-humidity trap that was producing
AP echoes on the radar set. The UFO l'eport states that temperature
inYersi.on,; were "prevalent" in the area.
In summary, this UFO incident appears to have heen caused IlY
radar AI' echoes and associated visual star sightings, both observed
at small angles through a surface teml'()raturc inversion-humidity
trap layer.
1O~._ Gulf of ~1('xico, off Louisiana coast (28 0
N 92° W),
6 !leco.';"ber 1952. IlS2S-()S:15 LST (1125 GMT). Weather: cleaT, dry,
li",ht winds, visibility excellent, full melon. '111e radio refractivity
220