Project Blue Book Special Report No. 14 (Analysis of Reports of Unidentified Aerial Objects)

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Group 5 -
Night sightings for which the sun was more than 10°
below the horizon and which were not included in
Group 4.
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Group 6 - Sunrise sightings for which the sun was between 0°
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and 10° below the horizon.
Group 7 - Sunrise sightings for which the sun was between O
0
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and 10° above the horizon.
These group numbers were punched on the cards and incorporated
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into the coding system. The number of OBJECT SIGHTINGS in each group
for each identification was then tabulated and is given in Table I.
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TABLE I
OBJECT SIGHTINGS
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Angle of Elevation Group
Identification
1
2
3
4
5
6
7
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Balloon
156
17
28
83
40
0
2
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Astronomical
52
6
43
236
118
9
6
Aircraft
187
23
49
144
60
5
2
Light phenomena
8
2
4
25
7
0
0
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Insufficient information
72
12
26
76
28
2
0
UNKNOWN
134
14
25
150
86
6
7
Other
64
8
12
50
36
3
7
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Total
673
82
187
764
375
25
24
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According to this table, a large majority of the KNOWN OBJECT
SIGHTINGS in Group 1 (343 out of 467) were either aircraft or balloons. In
Groups 4 and 5 combined, a large majority (681 out of 899) were either
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balloons, aircraft, or astronomical. Accordingly, a re-evaluation of the
UNKNOWNS in these three groups was planned with the objective of deter­
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mining which of the UNKNOWNS in Group 1 might possibly be aircraft or
balloons and which of the UNKNOWNS in Groups 4 and 5 might possibly be
balloons, aircraft, or astronomical objects. More will be said of this
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project later.
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Statistical Chi Square Test
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In the meantime, mirror graphs had been constructed from the fre­
quency tabulations which seemed to show that, when the KNOWNS (total less
UNKNOWNS) and the UNKNOWNS were grouped according to one of six
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characteristics, the percentage of KNOWNS and the percentage of
60
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