Project Blue Book Special Report (second copy)

Group 5 — Night sightings for which the sun was more than 10°
below the horizon and which were not included in
Group 4.
Group 6 — Sunrise sightings for which the sun was between 0°
and 10° below the horizon.
Group 7 — Sunrise sightings for which the sun was between 0°
and 10° above the horizon.
These group numbers were punched on the cards and incorporated
into the coding system. The number of OBJECT SIGHTINGS in each group
for each identification was then tabulated and is given in Table I.
TABLE I OBJECT SIGHTINGS
Identification
Balloon
Astronomical
Aircraft
Light phenomena
Insufficient information
UNKNOWN
Other
Total
1
156
52
187
8
72
134
.64
673
Angle
2
17
6
23
2
12
14
82
of
3
28
43
49
4
26
25
12
187
Elevation
4
83
236
144
25
76
150
* 50
764
Group
5
40
118
60
7
28
86
36
375
6
0
9
5
0
2
6
3
25
7
2
6
2
0
0
7
7
24
ff
i
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
balloons, aircraft, or astronomical. Accordingly, a re-evaluation of the
UNKNOWNS in these three groups was planned with the objective of deter-
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
project later.
Statistical Chi Square Test
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
characteristics, the percentage of KNOWNS and the percentage of
• . ' - • • 6 0