Project Blue Book Special Report (second copy)

SINGLE OBSERVATION - A SIGHTING consisting of a single
report from (1) one OBSERVER with no knowledge
of additional OBSERVERS of the same phenom-
enon, or (2) a group of witnesses of the same
phenomenon, each cognizant of the others. The
witness who made the report is called a SINGLE
OBSERVER.
MULTIPLE OBSERVATION - A SIGHTING consisting of
several reports from OBSERVERS of the same
phenomenon who were cognizant of each other.
The witnesses who made reports are called
MULTIPLE OBSERVERS.
ALL SIGHTINGS - (1) The group of reports consisting of one
report for each OBSERVER, including both
SINGLE and MULTIPLE OBSERVERS. (2) The
questionnaire, work sheet, and IBM card
representing the report from each OBSERVER —
in other words, the representation of each report
accepted for the statistical study.
UNIT SIGHTINGS - (1) The group of reports consisting of one
report for each SIGHTING, including all the
reports of SINGLE OBSERVATIONS and the one
. most representative report from each MULTIPLE
OBSERVATION. (2) The questionnaire, work
sheet, and IBM card representing the report for
each SIGHTING accepted for the statistical study.
A major serial number (four digits) was assigned to each sighting,
segregating the year of occurrence by selection of limits for each year, as
follows:
0001 to 0500
0501 to 1000
1001 to 1500
1501 to 2000
2001 to 2500
2501 to 4900
reserved
reserved
reserved
reserved
reserved
reserved
for 1947
for 1948
for 1949
for 1950
for 1951
for 1952
While this scheme would serve to identify any individual sighting, identifi-
cation of each report and its subsequent forms was necessary. The minor
subserial numbers (two digits) fulfilled this requirement. For all SINGLE
OBSERVATIONS, a major serial number followed by two (2) zeros, for
example, 2759.00, was sufficient identification. For MULTIPLE OBSER-
VATIONS, the major serial number followed by a series of two-digit num-
bers ranging from 00 to 99 was used to identify the individual reports. In
general, the most complete report from the most reliable observer of that
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