Project Blue Book Special Report No 14

----~.~ ..:_:._~,. / Approved fo..r: Release 2026 Under Section 1842 of the National Defen~5.e ,..,_ 1 6 64 2250 • Authorizati6n Ac -e' for Fiscal Year 2024 ~ 5'f.J _: FORM 1 (PLACE FORM qgo HERE) 0 FFI C/IAL RECORD J The, Agenc. in accc. additior, Records .,.---------- RETURN IMMEDIATELY AFTER USE TO THE CIA ARCHIVES AND RECORDS CENTER _ .,-<,y-; ~ -- --<-4H~ ~- _,.,/ FORM 6-64 2250 (PLACE FORM ~90 HERE} OFFICIAL RECORD COPY J WARNING The attached document (s) must be safeguarded. It is the Agency's Official Historical Record and must be preserved in accordance with the Federal Records Act of 1950. For additional information, call the Chief, CIA Archives and Records Center, extension 2468. RETURN IMMEDIATELY AFTER USE TO THE CIA ARCHIVES AND RECORDS CENTER -:/). I,._;· -C'.'.:'.: ?'e·--·('· ·~,-,1/i , ' ~ .. . r \ ..~.. ,=,. _._,_.- ~- : ~ ~ ·, . _.," _ : . - - - I _J: -~,,,, , -,_1: ... - ••,;-.,-·, C ~- j/ ) 'PROJECT BLLI ' B • I 1---7 I '/~ I ~~lt!L / ·~f·;•";,_,, ;: ~;..::;s.-..:.--:;_1-:,:,,•-'l(<..., - -... ~ · -....... --..._,,,!,.,,,,.,._ ·•21u,c< ,.,.. # ·, d'" ; • ti?0 .."""- 1 SJ SPECIAL REPORT N0.14 II I I I I I I I I I .I I I I I ,, l (ANALYSIS OF REPORTS OF UNIDENTIFIED AERIAL OB1ECTS) PROJECT NO. 10073 5 MAY 1955 \ AIR TECHNICAL INTELLIGENCE CENTER WRIGHT-PATTERSON AIR FORCE BASE OHIO Copy No. 35 --=---- PROJECT BLUE BOOK \I SPECIAL REPORT NO. 14 ' ii il 1 I I I I :1 (ANALYSIS OF REPORTS OF UNIDENTIFIED AERIAL OBJECTS) PROJECT NO. 10073 5 MAY 1955 I 1 11 ! ii I :I FOR OffIC!Al USt ONlY (AFR 190-16) !1 I I I I I _I AIR TECHNICAL INTELLIGENCE GENTER WRIGHT-PATTERSON AIR FORCE BASE o:mo No copyright materiel ls contained In this publication, I I I I I I I I I I I I I I I I I I I I I I TABLE OF CONTENTS vii SUMMARY. INTRODUCTION ORIGIN AND NATURE OF DATA 3 REDUCTION OF DATA TO MECHANIZED COMPUTATION FORM 4 4 Questionnaire . Coding System and Work Sheet Identification of Working Papers. Evaluation of Individual Reports 6 7 10 14 ANALYSIS OF THE DATA. Frequency and Percentage Distributions by Characteristics Graphical Presentation . Advanced Study of the Data Position of the Sun Relative to the Observer Statistical Chi Square Test The "Flying Saucer" Model 14 16 16 16 60 76 CONCLUSIONS 94 APPENDIX A. TABULATION OF FREQUENCY AND PERCENTAGE DISTRIBUTIONS BY CHARACTERISTICS 95 APPENDIX B. 255 WORKING PAPER FORMS LIST OF ILLUSTRATIONS Figure l Frequency of Sightings by Year for Object, Unit, and All Sightings 17 Figure 2 Distribution of Evaluations of Object, Unit, and All Sightings for All Years 18 Figure 3 Distribution of Object Sightings by Evaluation for All Years With Comparisons of Each Year for Each Evaluation Group • 19 Figure 4 Distribution of Object Sightings by Evaluation for All Years and Each Year 20 Figure 5 Distribution of Object Sightings by Evaluation Within Months for All Years 21 Figure 6 Distribution of Object Sightings by Certain and Doubtful Evaluations for All Years and Each Year • 22 Frequency of Object Sightings and Unknown Object Evaluations by Months, 1947-1952. 23 Distribution of Object Sightings by Sighting Reliability Groups With Evaluation Distributions for Each Group . 24 Distribution of Object Sightings Among the Four Sighting Reliability Groups for All Years and Each Year . 25 Figure 7 Figure 8 Figure 9 Figure 10 Distribution of All Sightings by Sighting Reliability Groups, Segregated by Military and Civilian Observers, With Evaluation Distribution for Each Segregation 26 Figure 11 Distribution of Object Sightings by Reported Colors of Object(s) With Evaluation Distribution for Each Color Group • 27 Figure 12 Distribution of Object Sightings by Number of Objects Seen per Sighting With Evaluation Distribution for Each Group 28 Figure 13 Distribution of Object Sightings by Duration of Sighting With Evaluation Distribution for Each Duration Group . 29 iii LIST OF ILLUSTRATIONS (Continued) Page Figure 14 Distribution of Object Sightings by Months Among the Eight Duration Groups for All Years 30 Figure 15 Distribution of Object Sightings by Shape of Object(s) Reported With Evaluation Distribution for Each Shape Group , 31 Figure 16 Distribution of Object Sightings by Reported Speed of Object(s) With Evaluation Distribution for Each Speed Group . 32 Figure 17 Distribution of All Sightings by Observer Location for All Years and Each Year 33 Figure 18 Comparison of Known and Unknown Object Sightings by Color, 1947-1952 34 Figure 19 Comparison of Known and Unknown Object Sightings by Number of Objects per Sighting, 1947-1952 35 Figure 20 Comparison of Known and Unknown Object Sightings by Speed, 1947-1952 36 Figure 21 Comparison of Known and Unknown Object Sightings by Duration, 1947-1952 37 Figure 22 Comparison of Known and Unknown Object Sightings by Shape, 1947-1952 38 Figure 23 Comparison of Known and Unknown Object Sightings by Light Brightness, 1947-1952 39 Figure 24 Comparison of Monthly Distribution of Object Sightings Evaluated as Astronomical Versus Total Object Sightings Less Astronomical. 40 Figure 25 Comparison of Monthly Distribution of Object Sightings Evaluated as Aircraft Versus Total Object Sightings Less Aircraft 41 Figure 26 Comparison of Monthly Distribution of Object Sightings Evaluated as Balloon Versus Total Object Sightings Less Balloon, 42 Figure 27 Comparison of Monthly Distribution of Object Sightings Evaluated as Insufficient Information Versus Total Object Sightings Less Insufficient Information 43 Figure 28 Comparison of Monthly Distribution of Object Sightings Evaluated as Other Versus Total Object Sightings Less Other 44 Figure 29 Comparison of Monthly Distribution of Object Sightings Evaluated as Unknown Versus Total Object Sightings Less Unknown 45 Figure 30 Characteristics Profiles of Object Sightings by Total Sample, Known Evaluations, and Individual Known Evaluations, With Unknown Evaluations Superimposed , 46 Figure 31 Frequency of Object, Unit, and All Sightings Within the U. S., 1947-1952, by Subdivisions of One Degree of Latitude and Longitude I I I I I I I I I I ,- 47 Figure 32 Distribution of Object Sightings by Evaluation for the Twelve Regional Areas of the U. S., With the Strategic Areas Located 48 Figure 33 Comparison of Evaluation of Object Sightings in the Strategic Areas of the Central East Region 49 Figure 34 Comparison of Evaluation of Object Sightings in the Strategic Areas of the Central Midwest Region 50 Figure 35 Comparison of Evaluation of Object Sightings in the Strategic Areas of the Central Farwest Region 51 Figure 36 Comparison of Evaluation of Object Sightings in the Strategic Areas of the South Midwest Region . 52 Figure 37 Comparison of Evaluation of Object Sightings in the Strategic Areas of the South West Region 53 iv I I I I I I I I I I I I I I I I I I I I I I I I I I LIST OF ILLUSTRATIONS (Continued) Figure 38 Comparison of Evaluation of Object Sightings in the Strategic Areas of the South Farwest Region . 54 Figure 39 Diagram of a Celestial Sphere. 56 Figure 40 Frequency of Object Sightings by Angle of Elevation of the Sun, Intervals of 10 Degrees of Angle. 57 Figure 41 Frequency of Object Sightings by Local Sun Time, Intervals of One Hour 59 Table 60 Object Sightings Table II Chi Square Test of Knowns Versus Unknowns on the Basis of Color 62 Table III Chi Square Test of Knowns Versus Unknowns on the Basis of Number 63 Table IV Chi Square Test of Knowns Versus Unknowns on the Basis of Shape 64 Table V Chi Square Test of Knowns Versus Unknowns on the Basis of Duration of Observation 65 Table VI Chi Square Test of Knowns Versus Unknowns on the Basis of Speed ti6 Table VII Chi Square Test of Knowns Versus Unknowns on the Basis of Light Brightness 67 Table VIII Chi Square Test of Revised Knowns Versus Unknowns on the Basis of Color 70 Table IX Chi Square Test of Revised Knowns Versus Unknowns on the Basis of Number. 71 Table X Chi Square Test of Revised Knowns Versus Unknowns on the Basis of Shape 72 Table XI Chi Square Test of Revised Knowns Versus Unknowns on the Basis of Duration of Ob~ervation 73 Table XII Chi Square Test of Revised Knowns Versus Unknowns on the Basis of Speed 74 Table XIII Chi Square Test of Revised Knowns Versus Unknowns on the Basis of Light Brightness. 75 I I I I I I I v and vi I I I I I I I I I I I I I I I I I I I I SUMMARY Reports of unidentified aerial objects (popularly termed "flying saucers" or "flying discs") have been received by the U.S. Air Force since mid-1947 from' many and diverse sources. Although there was no evidence that the ·unexplained reports of unidentified objects constituted a threat to the security of the U.S., the Air Force determined that all rep,orts of unidentified aerial objects should be fovestigated and evaluated to d,etermine if "flying saucers". represented technological developments not known to this country. In order to discover any pertinent trend or pattern inherent in the data, and to evaluate or explain any trend or pattern found, appropriate methods of reducing these data from reports of unidentified aerial objects to a form amenable to scientific' appraisal were employed. In general, the original data upon which this study was based consisted of impressions and interpretations of apparently unexplainable events, and seldom contained reliable measurements of physical attributes. This subjectivity of the data presented a 'major limitation to the drawing of significant conclusions, but did not invalidate the application of scientific methods bf study. The reports received by the U.S. Air Force on unidentified aerial objects were reduced to IBM punched-card abstracts of the data by means of logically developed forms and standardized evaluation procedures. Evaluation of sighting reports, a crucial step in the preparation of the data for statistical treatment, consisted of an appraisal of the reports and· the subsequent categorization of the object or objects described in each report. A detailed description of this phase of the study stresses the careful attempt to maintain complete objectivity and consistency. Analysis of the refined and evaluated data derived from the original reports of sightings consisted of (I) a systematic attempt to ferret out any distinguishing characteristics _inherent in the data of any of their segments, (2) a concentrated study of any trend or pattern found, and (3) an attempt to determine the probability that any of the UNKNOWNS represent observa.:. tions of technological' developments not known to this country. The first step in the 'analysis of the data revealed the existence of certain apparent similarities between cases of objects definitely identified .i.nd those not identified. Statistical methods of testing when applied indicated a low probability that these apparent similarities were significant. An attempt to determine the probability that any of the UNKNOWNS represeri'ted observations of technological developments not known to this country necessi­ tated a thorough re-examination and re-evaluation of the cases of objects not originally identified; this led to the conclusion that this probability was very small. The special study which resulted in this report (Analysis of Reports of Unidentified Aerial Objects, 5 May 1955) started in 1953. To provide the study group with a complete set of files, the informatio~ cut-off date was established as of the end of 1952. It will accordingly be noted that the statistics contained in all charts and tables in this report are terminated vii !I I with the year 1952. In these charts, 3201 cases have been used. As the study progressed, a constant program was maintained for the purpose of making comparisons between the current cases received after I January 1953, and those being used for the report. This was done in order that any change or significant trend which might arise from current developments could be incorporated in the summary of this report. The 1953 and 1954 cases show a general and expected trend of increasing percentages in the finally identified categories. They also.show decreasing percentages in categories where there was insufficient informa­ tion and those where the phenomena could not be explained. This trend had been:. anticipated in the light of improved reporting and investigating pro­ ceduJ;"es. Official reports on hand at the end of 1954 totaled 4834. Of these, 425 were produced in 1953 and 429 in 195'!. These 1953 and 1954 indi­ vidual reports (a total of 854), were evaluated on the same basis as were those received before the end of 1952. The results are as follows: Balloons - 16% Aircraft - 20% Astronomical - 25% Other - 13% 1 7% Insufficient Info Unknown - 9% As the study of the current cases progressed, it became increasingly obvious that if reporting and investigating procedures could be further improved, the percentages of those cases which contained insufficient information and those remaining unexplained would be greatly reduced. The key to a higher percentage of solutions appeared to be in rapid "on the spot" investigations by trained personnel. On the basis of this, a revised program was established by AF Reg. 200-2 Subject: "Unidentified Flying Objects Reporting" (Short Title: UFOB) dated 12 August 1954. This new program, which had begun to show marked results before January 1955, provided primarily that the 4602d Air Intelligence Service' Squadron (Air Defense Command) would carry out all field investigations. This squadron has sufficient units and is so deployed as to be able to arrive "on the spot" within a very short time after a report is received. After treatment by the 4602d AISS, all information is supplied to the Air Technical Intelligence Center for final evaluation. This cooperative program has re­ sulted, since 1 January 1955, in reducing the insufficient information cases to 7o/o and the unknown cases to 3%, of the totals. The period l January 1955 to 5 May 1955 accounted for 131 unidentified aerial object reports received. Evaluation percentages of these are as follows: viii I I I I I I I I I I I 1. I I I I I I I I I I - I I I I Balloons - 26% Aircraft - 21% Astronomical - 23% ..... I I ,, I I I I fi I r· I I Other 20% Insufficient Info - 7% Unknown 3% - All available data were included in this study which was prepared by a panel of scientists both in and out of the Air Force. On the basis of this study it is believed that all the unidentified aerial objects could have been explained if more complete observational data had been available. Insofar as the reported aerial objects which still remain unexplained are concerned, there exists little information other than the impressions and interpretations of their observers. As these impressions and interpretations have been replaced by the use of improved methods of investigation and reporting, and ,by scientific analysis, the number of unexplained cases has decreased rapidly towards the vanishing point. Therefore, on the b_asis of this evaluation of the information, it is considered to be highly improbable that reports of unidentified aerial objects examined in this study represent observations of technological developments outside of the range of present-day scientific knowledge. It is emphasized that there has been a complete lack of any valid evidence of physical 'matter in any case of a reported unidentified aerial object. [1 I I I I I I I I I ' ' f ix I I I I I I I I I ·1 I I I I I I I I I I I J INTRODUCTION In June, 1947, Kenneth Arnold, a Boise, Idaho, businessman and private pilot, publicly reported the now-famous sighting of a chainlike formation of disc-shaped objects near Mount Rainier, Washington. Result­ ing newspaper publicity of this incident caught the public interest, and, shortly thereafter, a rash of reports of unidentified aerial objects spawned the term "flying saucers". During the years since 1947, many reports of unidentified aerial objects have been received by the Air Force from many and diverse sources. The unfortunate term "flying saucer", or "flying disc", because of its widespread and indiscriminate use, requires definition. Many defini­ tions have been offered, one of the best being that originated by Dr. J. Allen Hynek, Director of the Emerson McMillin Observatory of The Ohio State University, who has taken a scientific interest in_the problem of unidentified aerial objects since 1949. Dr. Hynek' s definition of the term is "any aerial phenomenon or sighting that remains unexplained to the viewer at least long enough for him to write a report about it 11 ( 1). Dr. Hynek, elaborating on his definition, says, "Each flying saucer, so defined, has associated with it a probable lifetime. It wanders in the field of public in­ spection like an electron in a field of ions, until I captured' by an explana­ tion which puts an end to its existence as a I flying saucer' 11 ( 1). This definition would be applicable to any and all of the sightings which remained unidentified throughout this study. However, the term "flying saucers" shall be used hereafter in this report to mean a novel, airborne phenomenon, a manifestation that is not a part of or readily ex­ plainable by the fund of scientific knowledge known to be possessed by the Free World. This would include such items as natural phenomena that are not yet completely understood, psychological phenomena, or intruder air­ craft of a type that may be possessed by some source in large enough numbers so that more than one independent mission may have been flown and reported. Thus, these phenomena are of the type which should have been observed and reported more than once. Since 1947, public interest in the subject of unidentified aerial objects fluctuated more or less within reasonable limits until the summer of 1952, when the frequency of reports of sightings reached a peak, possibly stimu­ lated by several articles on the subject in leading popular magazines. Early in 1952, the Air Force's cumulative study and analysis of reported sightings indicated that the majority of reports could be accounted for as misinterpretations of known objects ( such as meteors, balloons, or aircraft), a few as the result of mild hysteria, and a very few as the result of unfamiliar meteorological phenomena and light aberrations. However, (1) Hynek, J. A.• "Unusual Aerial Phenomena"• Journal of the Optical Society of America. 43 (4). pp 311-314, April, 1953. 1 a significant number of fairly complete reports by reliable observers re­ mained unexplained. Although no evidence existed that unexplained reports of sightings constituted_ a 1>hysical threat to the security of the U. S., in March, 1952, the Air Force decided that all reports of unidentified aerial objects should be investigated and evaluated to determine if "flying saucers" represented technological developments not known to this country. Originally, the problem involved the preparation and analysis of about 1,300 reports accumulated by the Air Force between 1947 and the end of March, 1952. During the course of the work, the number of reports sub­ mitted for analysis and evaluation more than tripled, the result of the un­ precedented increase in observations during 1952. Accordingly, this study is based on a number of reports considered to be large enough for a pre­ liminary statistical analysis, approximately 4, 000 reports. This study was undertaken primarily to categorize the available reports of sightings and to determine the probability that any of the reports of unidentified aerial objects represented observations of "flying saucers". With full cognizance of the quality of the data available for study, yet with an awareness of the proportions this subject has assumed at times in the public mind, this work was undertaken with all the seriousness accorded to a straightforward scientific investigation. In order to establish the probability that any of the reports of unidentified aerial objects represented observations of "flying saucers", it was necessary to make an attempt to answer the question "What is a 'flying saucer'?". However, it must be emphasized that this was only incidental to the primary purpose of the study, the determination of the probability that any of the reports of un­ identified aerial objects represented observations of "flying saucers", as defined on Page 1. The basic technique for this study consisted of reducing the available data to a form suitable for mechanical manipulation, a prerequisite for the application of preliminary statistical methods .. One of International Business Machine Corporation's systems was chosen as the best available mechanical equipment. The reduction of data contained in sighting reports into a form suit­ able for transfer to IBM punched cards was extremely difficult and time consuming. For this study a panel of consultants was formed, consisting of both experts within and outside A TIC. During the course of the work, guidance and advice were received from the panel. The professional experience available from the panel covered major scientific fields and numerous specialized fields. All records and working papers of this study have been carefully preserved in an orderly fashion suitable for ready reference. These 2 I I I I I I I I I I I I I I I I I I I I I l I I I I I I I I I I I I I I I I I I I I I I records include condensations of all individual sighting reports, and the IBM cards used in various phases of the study. ORIGIN AND NATURE OF DA TA Reports of sightings were received by the U. S. Air Force from a representative cross section of the population of the U. S., and varied widely in completeness and quality. Included were reports from reputable scientists, housewives, farmers, students, and technically trained mem­ bers of the Armed Forces. Reports varied in length from a few sentences stating that a "flying saucer" had been sighted, to those containing thou­ sands of words, including description, speculation, and advice on how to handle the "problem of the I flying saucers 1 " . Some reports were of high quality, conservative, and as complete as the observer could make them; a few originated from people confined to mental institutions. A critical examination of the reports revealed, however, that a high percentage of them was submitted by serious people, mystified by what they had seen and motivated by patriotic responsibility. Three principal sources of reports were noted in the preliminary review of the data. The bulk of the data arrived at A TIC through regular military channels, from June, 1947, until the middle of 1952. A second type of data consisted of letters reporting sightings sent by civilian observers directly to A TIC. Most of these direct communications were dated subsequent to April 30, 1952, and are believed to be the result of a suggestion by a popular magazine that future reports be directed to the Air Technical Intelligence Center. As could be expected, a large number of letters was received following this publicity. A third type of data was that contained in questionnaire forms com­ pleted by the observer himself. A questionnaire form, developed during the course of this study, was mailed by A TIC to a selected group of writers of direct letters with the request that the form be completed and returned. Approximately 1,000 responses were received by ATIC. In general, the data were subjective, consisting of qualified estimates of physical characteristics rather than of precise measurements. Further­ more, most of the reports were not reduced to written form immediately. The time between sighting and report varied from one day to several years. Both of these factors introduced an element of doubt concerning the validity o,f the original data, and increased its subjectivity. This was intensified by the recognized inability of the average individual to estimate speeds, dis­ tances, and sizes of objects in the air with any degree of accuracy. In spite of these limitations, methods of statistical analysis of such reports m sufficiently large groups are valid. The danger lies in the possibility of 3 forgetting the subjectivity of the data at the time that conclusions are drawn from the analysis. It must be emphasized, again and again, that any conclusions contained in this report are based NOT on facts, but on what many observers thought and estimated the true facts to be. Altogether, the data for this study consisted of approximately 4, 000 reports of sightings of unidentified aerial objects. The majority were :re­ ceived through military channels or in the form of observer-completed questionnaires; a few were accepted in the form of direct letters from un­ -questionably reliable sources. Sightings made between June, 1947, and December, 1952, were considered for this study. Sightings alleged to have occurred prior to 1947 were not considered, since they were not reported to official sources until after public interest in "flying saucers" had been stimulated by the popular press. I I I I I I The plan for reduction of the data to usable form consisted of a pro­ gram of development comprising four major steps: ( 1) a systematic listing of the factors necessary to evaluate the observer and his report, and to identify the unknown object observed; (2) a standard scheme for the trans­ fer of data to a mechanized computation system; (3) an orderly means of relating the original data to_ all subsequent forms; and ( 4} a consistent pro­ cedure for the identification of the phenomenon described by the original data. I I I I I I I I I Questionnaire I REDUCTION OF DA TA TO MECHANIZED COMPUTATION FORM As received by the Air Technical Intelligence Center, the sighting reports were not in a form suitable for even a quasi-scientific study. A preliminary review of the data indicated the need for standardized interro­ gation procedures and supplemental forms for the reduction of currently held and subsequently acquired data to a form amenable to scientific appraisal. I The first reports received by A TIC varied widely in completeness and quality. Air Force Letter 200-5(2} and Air Force Form 112( 1) were attempts to fix responsibility for and improve the quality of the reports of sightings. To coordinate past efforts and to provide standardization for the (1) A modified Air Force Form 112 lists pertinent questions to be answered in regard to an unidentified-object sighting. (2) Air Force Letter 200-5 places responsibility with the Air Force for the investigation, reporting, and analysis of unidentified aerial objects. This letter is dated 29 April 1952. 4 I I I I I I I I I I I I I I I I I I I I I I I I I I I I future, it was imperative to develop a questionnaire form listing the factors necessary for evaluation of the observer and his report, and identification of the unknown objects. In addition, it was decided that such a questionnaire should be designed to serve as an interrogator's guide, and as a form for the observer himself to complete when personal interrogation was not possi­ ble or practicable. Ideally, a questionnaire for the purposes required should contain questions pertaining to all technical details considered to be essential for the statistical approach, and should serve to obtain a maximum of informa­ tion from the average individual who had made a sighting in the past or would be likely to be reporting sightings in the future. Besides these ~is­ crete facts, an integrated written description of a sighting would be re­ quired, thus enabling the reported facts of the sighting to be corroborated. Also, a narrative description might allow subtle questions to be answered concerning the observer's ability, such as indirect questions that would reveal his reasoning ability, suggestibility, and general mental attitude. As a whole, then, the information contained in a questionnaire should make possible the classification and evaluation of the sighting, the rating of the observer, the probability of accuracy of reported facts, and the identifica­ tion of what was reported by the observer as unidentified. During the course of this project, three questionnaire forms were developed, each intended to be an improved revision of the one preceding. The improvements were suggested and confirmed by members of the panel of consultants connected with this project. The original form was evolved by the panel of consultants as their first work on this project. It was intended to allow the start of the reduc­ tion of reports to discrete data, and was immediately subjected to exten­ sive review and revision by the panel. The revised ( second) form was subjected to a trial test before adoption. A TIC sent a copy to observers reporting sightings, with the request that the form be completed and re­ turned. Of the first 300 questionnaires returned during July and August, 1952, 168 were analyzed by a consulting psychologist. On the basis of this analysis, plus the experience gained in working with past reports, the final form of the questionnaire - the U. S. Air Force Technical Information Sheet - was evolved. Copies of the three forms of the questionnaire, in the order of their development, are shown as Exhibits BI, B2, and B3 in Appendix B. In order to implement the transcription of data from past sighting reports, each succeeding form was put to use as soon as it was developed and approved. Accordingly, experience was obtained with each form in relation to past data, an important factor in the improvement of the quality and completeness of the later reports included in this study. 5 Coding System and Work Sheet The reduction of non-numerical data to numerical form is mandatory in the machine handling of data. Thus, the selection of the IBM punched­ card system for analysis of data forced the adoption of a master coding plan. Since it was impracticable to transfer detailed data of a~ exact nature from the questionnaire to the IBM card, an intermediate transfer form, coordinated with the master code, was necessary. The master coding plan was evolved during the early stages of the preli~inary analysis of data, and was reviewed by the panel of consultants before use. It was recognized that this system of coding would be the heart of the analysis, that is, the completeness of the facility for trans­ lation of data could make or break the study. Accordingly, every conceiv­ able factor that might influence the identification of unidentified aerial objects was included, together with a wide range of variations within each factor. The original coding system (with minor corrections) was used throughout the translation of the original data with marked success. A copy of this system, called CODES, is enclosed as Exhibit IH, Appendix B. To facilitate the preparation of the punched-card abstract, an inter­ mediate form called the WORK SHEET (later, the CARD BIBLE) was developed. Referenced to both the data from the questionnaire and the sys­ tem of report identification, the WORK SHEET permitted an orderly transcription of data simultaneously by several people. In conjunction with the CODES, the WORK SHEET was used during the reduction of the original data to code form necessary for transfer to punched cards. A sample is included as Exhibit BS, Appendix B. After the analysis was under way, it became apparent that the me­ chanics of machine processing could be improved by incorporating in the IBM card system group classifications of certain factors requiring more than one column for discrete expression. In addition, the inclusion of certain data relating to the evaluation and bearing of the sun with respect to the observer was considered necessary. Finally, a critical examination of certain segments of the data indicated the need for the definition of a new factor relating to the maneuvers of the object or objects sighted. Prior to the start of the analytical study, it had been assumed that a com­ bination of stated factors would, by inference, define the maneuver pattern. All these additions have been incorporated in a revised set of CODES and CARD BIBLE that are illustrated as Exhibits B6 and B7, Appendix B. However, at the time that the maneuver factor was determined to be criti­ cal, it was physically impracticable to make the required definitions and re-evaluate the original data. Therefore, no code for maneuverability has been included in the CODES, CARD BIBLE, or IBM cards. 6 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I Identification of Working Papers The actual reduction of data to IBM punched-card form presented a problem of mass transfer of figures by several workers. Recognizing that an orderly system of relating the original data to the questionnaire, the WORK SHEET, and the IBM card was imperative, a scheme of SERIAL NUMBERS was developed to answer this need. The first data consisted of a series of letter-file folders identified by the year and location of the sighting or sightings they contained. The num­ ber of reports of sightings in a single folder varied from 1 to over 20. Under these conditions, there was a great possibility for incorrect tran­ scription of data, duplication of transcription, or misplacement of inter­ mediate forms. Further, it was considered desirable to relate all sightings of the same object or objects to one another. The concept of a four-digit serial number (major), followed by a two-digit subserial number (minor), was adequate to fulfill these requirements. To expedite handling of the data, temporary serial numbers were assigned until each report had been evaluated and the phenomenon had been placed i11:, a category of identification. The use of temporary serial num­ bers permitted the consolidation of duplicate reports from apparently diverse sources, such as a teletype message and an Air Force Form 112. However, this consolidation was made ONLY when it could be proved con­ clusively that the sources of the two documents were one and the same. Factors of the observer's location, date and time of observation, descrip­ tion of the phenomenon, and finally, the name of the observer were con­ sidered. In this manner, the assignment of major serial and minor sub­ serial numbers in continuous series was made only to the reports accepted for the statistical study. It is believed that the reports accepted represent unique and unduplicated instances of sightings. In the establishment of the serial-number system, it was necessary to define certain terms,' so that a standard interpretation could be achieved. The terms and corresponding definitions were: OBSERVER - Any witness reporting to a proper authority that he had seen unidentified aerial objects. SIGHTING The report or group of reports of the same observed phenomenon that remained unidenti­ fied to the observer or observers, at least until reported. 7 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 reserved for 1947 0501 to 1000 reserved for 1948 1001 to 1500 reserved for 1949 150lto2000 reserved for 1950 2001 to 2500 reserved for 1951 2501 to4900 reserved 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) fulfiiled 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 8 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I MULTIPLE OBSERVATION was identified with the . 00 subserial number. As an example, a MULTIPLE OBSERVATION consisting of six sighting reports would have the following serial numbers: 1132. 00 representing the best report and observer 1132.01 representing an additional observer 1132. 02 representing an additional observer 1132. 03 representing an additional observer 1132. 04 representing an additional observer 1132. 05 representing an additional observer During the course of the transcription of the data to machine card form, it became obvious that certain reports could have been independent observations of the same phenomenon. So, if the presentation of an analysis based on one report for each sighting was valid ( the concept of UNIT SIGHTINGS}, a presentation of an analysis based on one report for each phenomenon should be valid also. Further, the examination of data relating to the actual number of phenomena was considered to be the proper basis for assessing the probability of technological developments outside the range of present-day scientific knowledge. Therefore, a designation of OBJECT SIGHTINGS was established, with the following definition: OBJECT SIGHTING - ( 1) The group of reports consisting of one report for each phenomenon. (2) The questionnaire, work sheet, and IBM card representing a report for each phenomenon accepted for the statistical study. In brief review, ALL SIGHTINGS refer to all reports, UNIT SIGHTINGS refer to actual sightings, and OBJECT SIGHTINGS refer to the assumed number of phenomena. It must be recognized that the process of identifying OBJECT SIGHTINGS was deductive, while that for UNIT SIGHTINGS was definitive. A conservative approach was adopted in the determination of OBJECT SIGHTINGS, using the factors of date and time of observations, location of observers, duration of observations, and range, bearing, track direc­ tion, and identification of the phenomena. Any error of selection of OBJECT SIGHTINGS will tend to be in the direction of reducing the actual number of phenomena observed ( several instances of UNIT SIGHTINGS that might be one OBJECT SIGHTING were noted, but the evidence was not conclusive enough to justify consolidation of the reports). Following the determination of OBJECT SIGHTINGS, a series of serial numbers, called the INCIDENT SERIAL NUMBERS, was established to facilitate any future study of a specific object sighting. Each reported sighting that relates to an OBJECT SIGHTING received the same incident serial number, a four-digit code paralleling the major serial number series. 9 For machine manipulation, it was desirable to be able to select the sample of cards (all reports, all sightings, or all phenomena) to be in­ cluded in a particular study. The concept of a SIGHTING IDENTIFICATION NUMBER was evolved to fill this desire. Using one column of the IBM card, and the correlated working papers,· the code for this function was developed. Multiple punching eliminated the need to use several columns for discrete expression of the variations. Selection of the proper number in this column thus permitted selection of the desired sample of cards. Evaluation of Individual Reports Evaluation of sighting reports was recognized as a crucial step in the preparation of data for statistical treatment; inconsistent evaluations would have invalidated any conclusions to be derived from this study. A method of evaluation was, therefore, determined simultaneously with the develop­ ment of the questionnaire, the coding system, and the work sheet. It is emphasized that all phases of evaluation, even including the tedious prep­ aration of the original data for statistical treatment, were entrusted only to selected, specially qualified scientists and engineers. Evaluation consisted of a standardized procedure to be followed for: ( 1) the deduction of discrete facts from data which depended on human im­ pressions rather than scientific measurements, (2) the rating of the ob­ server and his report as determined from available information, and ( 3) the determination of the probable identification of the phenomenon observed. Categories of identification, established upon the basis of previous experi­ ence, were as follows: Balloon Astronomical Aircraft Light phenomenon Birds Clouds, dust, etc. Insufficient information Psychological manifestations Unknown Other The first step in evaluation, the deduction of discrete facts from subjective data, required certain calculations based on the information available in the sighting report. An example was the finding of the approxi­ mate angular velocity and acceleration of the object or objects sighted. Care was taken during this phase of the work to insure against the deduc­ tion of discrete facts not warranted by the original data. Thus, even though there was a complete lack of any valid evidence consisting of 10 I I I I ·1 I I I I I I I I I I I I I I I I I I I I I 1· I I I I I I I I I I I I I I I I I physical matter in any case of a reported unidentified aerial object, this was not assumed to be prima facie evidence that "flying saucers" did not exist. In those cases in which an attempt to reduce the information to a factual level failed completely, the report was eliminated from further con­ sideration, and thus not included in the statistical analysis. About 800 reports of sightings were eliminated or rejected in this manner. Most of these reports were rejected because they were extremely nebulous; the rest were rejected because they contained highly conflicting statements. The second step in evaluation, the rating of the observer and his report, logically followed the first step, the reduction of the data to usable form. Ratings were assigned on the basis of the following factors of in­ formation, considered in relation to one another: ( 1) The experience of the observer, deduced from his occupation, age, and training; ( 2) The consistency among the separate portions of the description of the sighting; (3) The general quality and completeness of the report; (4) Consideration of the observer's fact-reporting ability and attitude, as disclosed by his manner of describing the sighting. In cases in which insufficient information was available to make a judgment of the observer or report, none was made, but the report was accepted for the statistical study. The third step in the process of evaluation, the attempted identifica­ tion of the object or objects sighted, was done twice, first by the individual who made the transcription of the data (the preliminary identification), and later (the final identification} by a conference of four persons, two repre­ sentatives from ATIC and two from the panel of consultants. Although representatives of A TIC participated in making the final identifications, it must be emphasized that any previous identification of a sighting made by A TIC was not introduced or referred to in any way. In the coding system, the choices provided for final identifications were based on A TIC' s previous experience in analysis of the data. They had found that the majority of sightings could be classified as misinterpre­ tations of common objects or natural phenomena. Accordingly, categories for objects most frequently present in the air were provided. Balloons, aircraft, astronomical bodies ( such as meteors), birds, and clouds or dust were recognized as major categories. The less frequent, but common objects, such as kites, fireworks, flares, rockets, contrails, and 11 I meteorological phenomena like small tornadoes, were collected into a category called OTHER. A separate category for the uncommon natural phenomena associated with light reflections or refractions, such as mirages, sun dogs, inversion-layer images, and distortions caused by airborne ic.e, was established with the title of LIGHT PHENOMENON. Categories for INSUFFICIENT INFORMATION, PSYCHOLOGICAL MANIFESTATIONS, and UNKNOWN were provided for the sightings that could not be fitted into the preceding identifications. An explanation of their use follows: INSUFFICIENT INFORMATION - This identification category was assigned to a report when, upon final con­ sideration, there was some essential item of information missing, or there was enough doubt abou._t what data were available to disallow • identification as a common object or some natural phenomenon. It is emphasized that this category of identification was not used as a convenient way to dispose of what might be called "poor unknowns", but as a category for reports that, perhaps, could have been one of several known objects or natural phenomena. No reports identified as INSUFFICIENT INFORMA­ TION contain authenticated facts or impressions concerning the sighting that would prevent its being identified as a known object or phenomenon; PSYCHOLOGICAL MANIFESTATIONS - This identification category was assigned to a report when, although it was well established that the ob­ server had seen something, it was also obvious that the description of the sighting had been overdrawn. Religious fanaticism, a desire for publicity, or an over-active imagi­ nation were the most common mental aber­ rations causing this type of report; UNKNOWN - This designation in the identification code was assigned to those reports of sightings wherein the description of the object and its maneuvers could not be fitted to the pattern of any known object or phenomenon. For the purposes of this study, two groups of identifications were recognized, the KNOWNS (including all identification categories except the UNKNOWNS) and the UNKNOWNS. All possible identifications provided in the code system, except INSUFFICIENT INFORMATION and UNKNOWN, could be assigned accord­ ing to two degrees of certainty, designated "Certain" and "Doubtful". 12 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I A "Certain" identification indicated a minimum amount of doubt regarding the validity of the evaluation. By "rule-of-thumb" reasoning, the proba­ bility of the identification being correct was better than 95 per cent. A "Doubtful'' identification indicated that the choice was less positive, but that there was a better than even chance of being correct. It is emphasized again that, as was tr.ue for other phases of evalua­ tion, preliminary and final identification was entrusted only to scientists and engineers who, in addition to their broad scientific background, had received instruction, where necessary, in specialized subjects. The panel of consultants provided background information for this instruction. Many of the cases representing unusual features or maneuvers were submitted to and discussed with various members of the panel of consultants prior to the final identification. Consistency in the application of the knowledge necessary for making identifications was maintained by frequent collaboration among the person­ nel involved, and systematic spot checks of the work. In addition to the general fund of knowledge required to identify satisfactorily a reported unidentified aerial object, an attempt was made to correlate specific data such as flight plans of aircraft, records of balloon releases, weather con­ ditions, and an astronomical almanac with the reported sighting. The procedure followed in making final identifications deserves ex­ planation because of the importance assumed by the identification as a basis for statistical treatment. As was mentioned, a conference of four qualified persons, two from A TIC and two from the panel of consultants, decided upon the final identification for each sighting report. This work was done at A TIC, periodically, as reports became ready. During an identification conference, each sighting report was first studied, from the original data, by one person. If that person arrived at a decision, it was checked against the preliminary identification; if the two identifications were the same, the report was appropriately marked and considered finished. If the two identifications did not agree, the report was considered later by everyone participating in the conference until a group decision could be made. If an evaluator was unable to categorize the report as one of the common objects or as a natural phenomenon, and his opinion was that the sighting should be recorded as UNKNOWN, a group decision was also re­ quired on that report before it was considered finished. A group decision was necessary on all reports finally recorded as UNKNOWN, regardless of what the preliminary identification had been. In cases where a group decision was not made within a reasonable time, the report was put aside and later submitted to certain members of the panel of consultants for their op1n1ons. If, after this, disagreement continued to exist, the report of the sighting was identified as UNKNOWN. 13 Upon completion of final identifications, all data were transferred to IBM cards, preparatory to analysis. ANALYSIS OF THE DA TA Broadly stated, the problem at this point consisted of the judicious application of scientific met~ods of categorizing and analyzing the sub­ jective data in reports of sightings of unidentified aerial objects. It was recognized that an approach to this problem could best be made by a sys­ tematic sorting and tabulation program to give frequency and percentage distributions of the important characteristics of sightings. A suggestion that an attempt be made to anticipate all questions that might be asked in the future about a sighting or a group of sightings, and to provide answers, was rejected. The systematic approach also made it possible to develop a detailed reference manual of the attributes of the sightings included in this study. Thus, at the beginning of the analysis, a detailed plan was developed for sorting, counting, and tabulating the information from the punched-card abstracts of reports of sightings. It was believed at the time, and later substantiated, that the results of the program for sorting and tabulating would serve as a, guide for the more sophisticated treatment involving statistical methods. Also, it was anticipated that any patterns or trends that might be found could be subjected to concentrated study in the hope of discovering significant information relating to the characteristics of "flying saucers". Further, it was believed that these trends could serve as certain of the criteria of validity for any concepts (models) developed in the attempt to discover a class of "flying saucers". The three parts of this study ( 1) the sorting and tabulation program, (2) the advanced study of the results of that program, and (3) the investiga­ tion of the possibility of conceiving a model of a "flying saucer" from descriptions reported, are discussed in sections entitled "Frequency and Percentage Distributions by Characteristics", "Advanced Study of the Data", and "The I Flying Saucer' Model". Frequency and Percentage Distributions by Characteristics The original conception of this study assumed the availability of sufficient data to describe adequately the physical appearance, maneuver characteristics, range, direction, and probable path of the object or objects observed. However, familiarity with the data, acquired during the 14 I I I I I I I I I I I I I I I I I I I I I I I ~ I\L, I I I I I I I I I I I I I I I 'I I translation and transcription from reports to punched cards, indicated that there would be relatively few specific variables or factors that would yield meaningful correlation studies. Either the original data were too subjec­ tive, or the incompleteness of the original reports-wo1J:_ld seriously reduce the sample of a specific variable. Preliminary tabulations of various sortings substantiated the im­ possibility of deriving statistical results from certain variables, such as movement of the observer during the sighting, sound, shape parameter, size, angular velocity and acceleration, appearance and disappearance bearing, initial and final elevation, altitude, and orientation of the object. The statistically usable variables presented in this study include the date, time, location, duration, reliability, and method of observation of the sighting, and the physical attributes of number, color, speed, shape, light brightness, and identification of the objects sighted. The presentation of frequency and percentage distributions of any of the variables must be interpreted in the light of the sample of incidents represented. For example, the analysis of the reported colors of the objects sighted, based on ALL SIGHTINGS, could lead to misrepresenta­ tion of the distribution of the reported color of the objects, because of the multiplicity of reports on some of the phenomena. On the other hand, the percentage distribution of the light brightness reported by each observer is more likely to be correct than a distribution based on one report for each phenomenon. To assure that the most nearly correct presentation was made, and to avoid the possibility· of failure to uncover any pattern or trend inherent in the data, the variables were studied on five different bases or samples. These samples, and their numerical relation to each other, were as follows: ALL SIGHTINGS (all reports) UNIT SIGHTINGS, all observers UNIT SIGHTINGS, single observer UNIT SIGHTINGS, multiple observers OBJECT SIGHTINGS The preliminary tabulations indicated that the samples based on UNIT SIGHTINGS, single observer, and UNIT SIGHTINGS, multiple observers, would not add materially to this study. Accordingly, although the fre­ quency distributions were recorded and are available for study, they are not presented in this report. The bases of ALL SIGHTINGS, UNIT SIGHTINGS ( referring to all observers), and OBJECT SIGHTINGS are presented in Appendix A as Tables Al through A240. A critical study of these tabulations reveals that there is no apparent change in the distribution of any variable from one basis to another, and that no marked patterns or trends exist in any sample. _I 15 I 3,201 cards 2, 554 cards 2, 232 cards 322 cards 2, 199 cards Graphical Presentation Graphical representation of the important information contained in the tables is presented in Figures l through 38. These figures present the distributions of the important variables only by the total nu.mber of cases in each identification category, since no significant differences were found between the distributions of "Certain'' and "Doubtful" identifications of objects with respect to the variables. A chronological study of these figures will afford a broad picture of the tabulated information, without the necessity of a detailed study of the tables. A critical examination of the figures will show that no trends, patterns, or correlations are to be found, with the exception of Figures 18 through 30. The apparent similarity of the distributions shown by these mirror graphs, Figures 18 through 23, was tested by statistical methods which showed that there was a low probability- that the distributions of the KNOWNS, and UNKNOWNS by these characteristics were the same. These tests and their interpretation are discussed in the following section. For purposes of this study, the strategic areas, shown in Figures 32 through 38, and Tables A223 through A240, Appendix A, were designated on the basis of concen­ tration of reports of OBJECT SIGHTINGS in an area. No other interpre­ tation of the tables or remaining charts was deemed necessary. Advanced Study of the Data It was recognized that the lack of any patterns or trends, as shown by the tabulations and graphs, provided an insecure basis for drawing definite conclusions. Accordingly, shortly before the sorting and tabulation pro­ gram was concluded, a program of study of the data was developed to utilize statistical and other mathematical methods, which could lead to a more concrete interpretation of the problem. Position of the Sun Relative to the Observer The first thing that was done was to calculate the angle of elevation of the sun above the horizon and its bearing from true north as seen by the observer at the time of each sighting. With this information, it could then be determined whether there was a possibility that the reported object could have been illuminated by light from the sun. In addition, it could be determined whether an object could be a mock sun ( sun dog) or whether there was a possibility of specular reflection from an aircraft at the posi­ tion of the object, which would give the appearance of a "flying disc". A program of computation was set up and carried out to obtain the angle of elevation and the bearing of the sun for each sighting. All informa­ tion needed for this calculation was available on the deck of IBM cards. 16 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I ,1952, 1501= 68.3% I I I I I Object sightings 2199 =100% All sightings 3201 = 100% FIGURE I FREQUENCY OF SIGHTINGS BY YEAR FOR OBJECT, UNIT, AND ALL SIGHTINGS A-7479 I I I ~ Unit sightings 2554 =100% 17 474 =21.5% Object sightings 2199=100 % All sightings 3201=100% Unit sightings 2554= 100% FIGURE 2 DISTRIBUTION OF EVALUATIONS OF OBJECT, UNIT, AND ALL SIGHTINGS FOR ALL YEARS A-7480 I­ I I I I I I I I I I I I I I I I I I I 18 I I I I I I I I I I I I I Unknown 434=19.7°1. Astronomical 479 =21.8 % 1952 Aircraft I I I I I I I I FIGURE 3 DISTRIBUTION OF OBJECT SIGHTINGS BY EVALU­ ATION FOR ALL YEARS WITH COMPARISONS OF EACH YEAR FOR EACH EVALUATION GROUP A•7411 I I 11 19 No. of object sightings 100 +­ 2199 79 143 186 169 121 1501 100 90 90 80 80 70 70 60 60 50 50 40 40 30 30 20 20 10 10 c ~ ~ ro 0 Q,J a. 0I C\\.\.:::<::<>0)J - •• L>,,),,),,),,\.'\'\1 1947 l'\;\'\\:\,'\'\'1 1948 I\'\»),),).);! 1949 N>,'\',,'\'\>)j 1950 I\Y\'\\.'\'\"l 1951 RL~ I0 1952 FIGURE 4 DISTRIBUTION OF OBJECT SIGHTINGS BY EVALUATION FOR ALL YEARS AND EACH YEAR A-7 4 82 ---------------------No. of object sightings 70 I F+--1 ;..I 55 11 I I 11 83 11 I I I 11 127 129 11 I I I I I I I I 11 183 638 407 166 125 106 11 I I I I I I I I 11 11 I I 11 I I I I 11 11 I I 11 I I I I II 105 11 I I 11 1100 90 "'Cl ·=.c 80 80 cn 7 0 70 +- Cl +­ u cu :.0 60 0 60 "' .c c0 50 50 ~ 40 40 - 30 30 u'­ 20 20 ~ "' 0 LLJ 0 +­ c cu cu a. 10 10 0 I l>.':u>l I\»'\'I l>,V0J l\'\:0::1 ~ ~ Jon Feb Mor Apr Moy June l'\'001 J:00-:\'I July Aug L),'\).)I Sept ~ J l'\'\)-'::J l\»>.J Oct Nov I0 Dec FIGURE 5 DISTRIBUTION OF OBJECT SIGHTINGS BY EVALUATION WITHIN MONTHS FOR ALL YEARS A-7413 20 30 0 10 30 20 10 Astronomical All years I I I 1947 1948 1949 1950 1951 195 2 I I I I I I I I I I. I Aircraft I All years I I I 1947 1948 1949 1950 195 I 195 2 I I I I I I I I I I Balloons All years I I 1947 1948 1949 1950 195 I 195 2 I I I I I I I I I I I lnsuf. info. I All years I 1947 1948 1949 1950 195 I 195 2 I I I I I Unknown I I All years 1947 1948 1949 1950 195 I 1952 I I I I I Other All years 1947 1948 1949 1950 195 I 1952 30 20 10 Certain 0 Per Cent 10 20 30 Doubtful FfGURE 6 DISTRIBUTION OF OBJECT SIGHTINGS BY CERTAIN AND DOUBTFUL EVALUATIONS FOR ALL YEARS AND EACH YEAR A•7414 22 I I I I I I I I I I I I I I I I I I I I I I ---------------------5001 400 ., "' "' sot ~ 50t r::: X r-MK X\ -ISO 1so C :;: .t::. .... II) u ~ 0 0 "' c,a ..... 40t I IX XTTIX X 30t VI I<. X rTT1 X X-130 -f40 .0 E ::, z 20 20 10 10 01 I J F M A M J J I JX A s O N 01 J 1947 X a::,::,,,l::±-¥ tf::::3>H::::t:><I :- l'Y:I Cl s O N O IJ F M A M J J A s O N O IJ 1948 1949 F M A M J J A :-1 7 1'¥""-Y£1 l r I I I I I I I I I 110 s O N DI J F M A M J J A s O N DI J F M A M J J A s O N D 1950 1951 1952 F M A M J J A FIGURE 7 FREQUENCY OF OBJECT SIGHTINGS AND UNKNOWN OBJECT EVALUATIONS BY MONTHS, 1947-1952 C-7485 Astro- n Astro­ nomical Unknown =22.8 I 71=33.3% I \ I '\ I \ I I \ \ I \ \\ I/ I I \ /Excellent lnsuf. info. 9=4.2 o/o \ I I I I I I '' '' '' ' 2199= 100 o/o I '' I I I I I '' \ ' I /I Doubtful / / / ' ,' / / I ' I I I I I I I ' I I ' I Good '' '' \ Unknown Astr nomic 188 = -2 24.8 o/o I I croft lnsuf. info. 27=3.6% FIGURE 8 DISTRIBUTION OF OBJECT SIGHTINGS BY SIGHTING RELIABILITY GROUPS WITH EVALUATION DISTRIBUTIONS FOR EACH GROUP A-748S 24 I I I I I I I I I I I I I I I I I I I I I I ---------------------No. of object sightings 2199 100 79 186 143 90 t-- ' ' ', 80 ,- - ,, ,, I' ' -- -- ,, '' I 100 , ,,, ',, ---- ,, --- - 90 - 80 ', ', I - cu u... 50 - I ---- - 10 ', / I 60 ,- C N) (JI 1501 Good I ~ 121 I Excellent 70 169 _, , --- '' I ----- _v ', - 60 ', - 50 cu a. 40 t-- --- Doubtful ' '' I 3011- I I I 10i"" 0I ' - 30 ' '' I ----- - 20It- - 40 r, I I '' Poor I I '' I I '' - 10 I I I All years 1947 - 20 ' ', 1948 1949 1950 FIGURE 9 DISTRIBUTION OF OBJECT SIGHTINGS AMONG THE FOUR GROUPS FOR ALL YEARS AND EACH YEAR 1951 SIGHTING 1952 - 0 RELIABILITY A-74 87 (>' •-:-..v 0~ 0~ ,~ t/-"' ~ ~ 6 -- 2's- - , ~ ~0· ~ ·,$' ~(:- t- (:-0 .;/' <c~(:-;_o~~~ CJ~ ~00~- ~ so-- 1Slbb \o 1 1 ■111111 2s s'o • 1 s -,ob \b 1 21s s'o T's ~ ~~~ ~ ~ ,db\6 21s s'o 1s 100 45r-l---Per Cent_ _ / _ \ ~ - - - - - - - - / ~ - - - - - - - - / _ \ _ _ _ _ _ _ _ _/_ 4Qt--1------------J-l-----------/---\---4""'-------..---I-I------------J-- 3 St--1------------,--1-----------,---1-"' , __ - 3 Qt--1-----------' ~ ~ 20t--1-------- 1---1-- 1--------- 1-- I 5t-- \--------I---- I - 1---------1- 1--------1-- 1----------1- - - - - - 1--1 ~ 1--,-----1 - - uCcu 2 S t - - - 1 - - - - - _ : __ __ 1 - - - 1 - - Civilian IOI 51 01 I I Civilian e [ t----- 0 Military J I Excellent I Military 1------ I I Good Civilian ------1-- W Military ! Ci villa n 1-----1 - - i--------1 ! Doubtful f--•---- ':j Military I Poor FIGURE 10 DISTRIBUTION OF ALL SIGHTINGS BY SIGHTING RELIABILITY GROUPS. SEGREGATED BY MILITARY AND CIVILIAN OBSERVERS WITH EVALUATION DISTRIBUTION FOR EACH A-1411 SEGREGATtON I I I I I I I I I I I I I I I I I I I IQO,r,:::+=+=11=+:+:::i:+r-r.r-r..r:,-0.;:r+:r+.:r~i-T~_f1_J7...,. 7'_J-rr.._ 7...,. 90 r...,.r-1-1rr-"'[_"I."I.T..LL~n, IO 0 .._ri.....rrwwT---1-T---1-T .... 90 Unknown 80 70 60 +­ +­ c c u u cu cu 50 "­ cu L.. cu a. a. 40 30 20 10 \ I I \ \ I \ I I \ ' White Metallic 23.5 % 17.7% i, Not stated OrangE Red 12.3% 10.0% 8.1% Other 28.4% FIGURE II DISTRIBUTION OF OBJECT SIGHTINGS BY REPORTED COLORS OF OBJECT(S) WITH EVALUATION DISTRIBUTION FOR EACH COLOR GROUP A•7419 I I I +-r+-r _,_T_._,- 27 ~,....,....,....,....r-T""S....,...,-100 1008060- I I >-+-i---+-+.......,._+-+---<__. - 80 ~~~~~~~~~ - 6 0 11 or more objects ~~-0~·~~'Y,f 66=3.0% 3-10 objects 255= 11.6 % 0. 40- ::::, 0 -- "C ~ (!) cu 20- - ·.t::. 31'; -20 <!> 0 C C .t::. (I) 0- C cu 100- ~~ u 0 0 ~ (\J (0 a.. 80- (I) cu O') :0 (X) (.) cu 0 C II O') I object 1636= 74.4% 0 II o (0 - - ~ u cu . °EN v C ~,...,..T""T""'S,..........~ - IO O cu (.) ~ ;c:...~-<":-<":v:vvccc; cu ,,....,,...."",,v'X,Y~'C◊O: - 8 0 Q.. ~ cu .0 E ::::, 60- z 1----------i- 60 4020- 100- .................- ........o. t-+-+-+-+-+-+-,r-+-t-+t Unknown -20 ::::, o_ e 80-~~V~v"~V'~-~.,.._.,..ic:J',.~ Others (!) lnsuf. info. c - Balloon -c 40cu Aircraft :C 6031'; (.) ~ cu 20- a.. Astronomical FIGURE 12 DISTRIBUTION OF OBJECT SIGHTINGS BY NUMBER OF OBJECTS SEEN PER SIGHTING WITH EVALUATION DISTRI­ BUTION FOR EACH GROUP A-74 90 28 I I I I I I I I I I I I I I I I I I I I ---------------------- - --~--------------------------------------------- 1J ! J..111~~ mm !!!!!!m eo-1 ~':.~.~. / / ' ~111111-1-----------,1111 1111111 1111111111111~_~1---------,-11111 I111111 1 1 1 1 lnsuf. info. 100---~-----~~~~~ 9 0-1 70 . ~ = ~ No t ~ov;ra~.mi ~ ~ / ; , • 61 ::~ ;~;.in 40 30 /~~"'TTT"l7"7"''7"7"'7"?'"7~~~ - ~~~:.- ~r::i IIIIIIIIIIIIIIIIIl~_~~mffll 11111111111111 /~~-IIIIIIIIIIIIIIIIIIIIIR===:=filllllllllllll lllll ✓~:::~I 11111111111111111111111~-====:~BI 1111111111 5 -~:~30·::: : ~: :~e?:: :::::-111111111111111 ~;:==;=91111111111111 -,,~-1,1111111,11m1111111 O-D~;~t!;:n 0 IO 20 30 40 50 60 70 80 90 100 Evaluations in Per Cent FIGURE 13 DISTRIBUTION OF OBJECT SIGHTINGS BY DURATION OF SIGHTING WITH EVALUATION DISTRIBUTION FOR EACH DURATION GROUP A- 7491 No. of object sightings 70 100 55 83 127 12.9 - 63_8 183 407 L25 - -1.66 106 LOS I 90I· 90 Not statec en Cl C . :;: 80 - / / .c. Cl ·(/) - u ,, 70 - Cl) 'B 0 60 I \' '\ ' I 1:0 50I u • I I) ,., / I I I '' I '\ - - '' '' I II ' I .. - I" -w 0 30I 10-1v CV U 20 r sec Cl) 10 I - ,; ,;' - ' I\ ~· ,;' V \ .,. ,,· \ '\'\• 5 sec ond less / ' I' ... I' ' V I I '' I \ ..' ~ / ' ,,. ... / I' ,-, - II . 20 -,,,· .,,. ....... ,,,, . 30 f I I I .. -, . 40 I I ' I .. ,-, ' 5 0 '­ Cl) a. I I I '\ .. / (.) I I \ - r, - ,,· I" I' ' ,,, / ~ \ I I' - ·, \ ' ' '­ a. ; 1·, Cl) \ \ \ 10 0 Jon Feb Mor Apr 0 May June July Aug Sept Oct Nov C \ \ I1_-~y se_e C \ \ to ;;; 5min \ 60 I I I ~ 40I U)I 0 I I I \ -- ;' 70 I I ' ' ' o 61sec II II '\\ \ - . 80 I \ ' ,; r I i min .c. "' I ,-, I '' -"' .... I ,I I I\ 6-30 en 0 I fn;;in - ~ ~ 100 Dec FIGURE 14 DISTRIBUTION OF OBJECT SIGHTINGS BY MONTHS AMONG THE EIGHT DURATION GROUPS FOR ALL YEARS A-7492 ---------------------100- ___ ......,..,,,,,,,,,, .......-K\'.\,\.\.\.\.\.\.\l 11 11 I 1111 I P/7?777J1f------txx5o&'x54 I I I I I I 111111 I 11 lnsuf. info 23.5% 90- Not stated ---i'·"~::-.1II III II I 1•::====~111I IIIII I III --------r-f;'~ilIIII IIIII~ I I I I IIII \~~:~11111111111111~:====;::====::-[ 111111 1111• 4\~11111111111111111111111~~::==:=-.IIIIIIIIIII i. .--.J, .:~: _ _ 111111.1111111.I ~ .11111111 I.I 111111 80- Other 70- Flam 60- enticular C: QJ 0 50- ~ QJ (II Q. 40- 30- 20- Elliptical I \\ ~ 10- o_ Shape 0 10 20 30 40 50 60 70 80 90 Evaluation in Per Cent FIGURE 15 DISTRIBUTION OF OBJECT SIGHTINGS BY SHAPE OF OBJECT(S) REPORTED WITH EVALUATION DISTRIBUTION FOR EACH SHAPE GROUP A-7493 100 ioo-r-----------K'Z\:\.~\:i 11111111111 IV/T///1 .KXXXX?t 111 I I 1111111 90- 11111~~~::::::=::::~111111111111 eO-ln;~::~ed' ,/~~ ~ : ~I ffl • ~-u ;:::~:~II I111111111111111 ~t:==:=:;: : : : : ==~t: :=: : =jgm I1111111111111111 ~ i ::~ :~i~t / i B II II IIII IIII IIIl~t=:::=:::=t:=:::::::=:::=::::::::~91111111111111111 : ~:~;~~~o :~::;~]! 1111111111~~11111111111 ~~~~:-1,111111.-t:::==c::::==:t:::==,_____ffl 1111 l1111111 1 :~ 15t :~::Y 0 · 10 20 30 40 50 60 70 80 90 Evaluation in Per Cent FIGURE 16 DISTRIBUTION OF OBJECT SIGHTINGS BY REPORTED SPEED OF OBJECT(S) WITH EVALUATION DISTRIBUTION FOR EACH SPEED GROUP A-7494 100 ---------------------No. of all sighting 3201 100- 117 Location not stated , ... ... ~ 90- ... +­ &, 80<11 205 ,,, '' ., ,/' - 164 ' ' ', I I ~ 40- I \ I \ Outdoors \ -60 ,, c <11 u " .c ,,-- 1_-:;.,' +- 30- In bldg. ',/ / '' / In plane ,.,,., '\ \ , \,,, -40 ,, ~ \ \ / ,.,, \ \ \ -30 \ \ -20 ,.,,,, ,,,- ' II 10- ., 11~," ...... _ I,. "20o. ,,,, ,,, ~~ '' , , I, ,,, -50 ' ,, ~ \ // , ,, , ~ ~ ~ ~ .--:._,,,,,, ' +­ -70 I \ 0 -so I \ ~ (1,1 0 '' I \ f/) c,,.._ '' I 70- +- ' -100 -90 ~ I \ ·-"' 60.c ·-"' 50- 2018 160 I 0:: u, C 306 ' ' , ... --- -- _, , ---- ........ -10 In car 0 _Q All years 1947 1948 1949 1950 1951 1952 FIGURE 17 DISTRIBUTION OF ALL SIGHTINGS BY OBSERVER LOCATION FOR ALL YEARS AND EACH YEAR A-74 95 Unknown Per Cent Total Less Unknown Pe-r Cent I 30 25 20 15 10 5 I I I I I I 0 0 5 I 10 I 15 I 20 I 25 I 30 _1 _j White Meta II ic Not stated Of ~ Orange Red Other FIGURE 18 COMPARISON OF KNOWN AND UNKNOWN OBJECT SIGHTINGS BY COLOR,1947-1952 A-7496 -~-------------------Total Less Unknown Per Cent I Unknown 80 70 60 50 40 30 20 10 I I I I I I I I 0 0 IO 20 Per Cent 30 40 50 60 70 80 One Two c,, Three to ten (JI .. Eleven or more ■ ■ Not stated ■ FIGURE 19 COMPARISON OF KNOWN ANO UNKNOWN OBJECT SIGHTINGS BY NUMBER OF OBJECTS PER SIGHTING, 1947-1952 A- 7497 Total Less Unknown Per Cent I Unknown Per Cent 40 35 30 25 20 15 IO 5 I I I I I I I I 0 0 5 IO 15 20 25 30 35 40 I I I I I I I I I Stationary Less than 100 mph 100 to400 mph (1,1 0) - More than 400mph Meteor-Ii ke - Not stated FIGURE 20 COMPARISON OF KNOWN AND UNKNOWN OBJECT SIGHTINGS BY SPEED, 1947-1952 A-7491 ---------------------30 Total Less Unknown Unknown Per Cent Per Cent 25 20 15 10 5 0 0 5 seconds or less t 5 10 15 20 25 30 6-10 seconds 11-30 seconds "'...a 31-60 seconds 61 seconds 5 minutes 6-30 minutes More than 30 minutes Not stated FIGURE 21 COMPARISON OF KNOWN AND UNKNOWN OBJECT SIGHTINGS BY DURATION, 1947-1952 A-7499 Total Less Unknown Per Cent 50 45 40 35 30 25 20 15 Unknown 10 5 0 0 5 10 Per Cent 15 20 25 30 35 40 45 50 Elliptical Rocket and aircraft Meteor or comet c,, a, U Lenticular, conicol or teardrop Flame Other shop, Not stated FIGURE 22 COMPARISON OF KNOWN AND UNKNOWN OBJECT SIGHTINGS BY SHAPE, 1947-1952 A•7500 ---------------------Total Less Unknown Per Cent I 60 I 50 I 40 I 30 I 20 I 0 0 10 I - -/ (1,1 U) Sunlight on mirror or aluminum Sunlight on plaster, stone or soil IO I 20 I Unknown Per Cent 30 40 I I 50 I 60 I I - Brighter than moon - ~ Like moon ,... ... .. - - Duller than moon ... ' Not stated Fl GURE 23 COMPARISON OF KNOWN AND UNKNOWN OBJECT SIGHTINGS BY LIGHT BRIGHTNESS, 1947-1952 A•7501 Total Less Astronomical Per Cent 40 30 20 10 Astronomical Per Cent 0 0 j January 10 20 30 40 t February March April .. 0 May June July August September October November December FIGURE 24 COMPARISON OF MONTHLY DISTRIBUTION OF OBJECT SIGHTINGS EVALUATED AS ASTRONOMICAL VERSUS TOTAL OBJECT SIGHTINGS LESS ASTRONOMICAL A-7502 ---------------------Total Less Aircraft Per Cent 40 30 20 10 Aircraft Per Cent 0 0 January 10 20 30 40 t February March April May June ~ July August September October November December FIGURE 25 COMPARISON OF MONTHLY DISTRIBUTION OF OBJECT SIGHTINGS EVALUATED AS AIRCRAFT VERSUS TOTAL OBJECT SIGHTINGS LESS AIRCRAFT A-7503 Balloon Per Cent Total Less Balloon Per Cent 40 30 20 10 0 l 0 January 10 20 30 40 t February Morch April Moy June ~ I\) July August September October November December FIGURE 26 COMPARISON OF MONTHLY DISTRIBUTION OF OBJECT SIGHTINGS EVALUATED AS BALLOON VERSUS TOTAL OBJECT SIGHTINGS LESS BALLOON A-7 504 ---------------------lnsuff icient Total Less lnsuff icient Information Information Per Cent Per Cent 40 30 20 10 \ I I I 0 0 10 20 30 40 j January February March April May • c,, June July August September _ October November December FIGURE 27 COMPARISON OF MONTHLY DISTRIBUTION OF OBJECT SIGHTINGS EVALUATED AS INSUFFICIENT INFORMATION VERSUS TOTAL OBJECT SIGHTINGS LESS INSUFFI­ CIENT INFORMATION A-7505 --/ Total Less Other Per Cent 40 30 20 10 0 0 January 10 Other Per Cent 20 30 40 t February March April May .. June July August September October November December FIGURE 28 COMPARISON OF MONTHLY DISTRIBUTION OF OBJECT SIGHTINGS EVALUATED AS OTHER VERSUS TOTAL OBJECT SIGHTINGS LESS OTHER A-7506 ---------------------Unknown Per Cent Total Less Unknown Per Cent 40 30 20 10 0 0 j January 10 20 30 40 t February March April May June ~ u, July August September October November December FIGURE 29 COMPARISON OF MONTHLY DISTRIBUTION OF OBJECT SIGHTINGS EVALUATED AS UNKNOWN VERSUS TOTAL OBJECT SIGHTINGS LESS UNKNOWN A•7507 90 80 - - C Cl> -co 60 ... ~ cu 40 a. 20 \ C ~ C Cl> C ~ a. Cl> 20 - - C Cl> 1/) Unknown ,a:.._ 60 <i ~ 40 , , '' (.) - -- !/ ,/ C a§ 60 -C (.) 40 Cl> - cu m a. 20 0 ._ Cl> - .s::. -(.) C Cl> 60 Cl> a. 20 \ '~ \ ~ \ I \\._ ;, -~ ,..:::.. \ ~---- v J,, - ,:,,, ' "-.J.; [\,..::. / ' f-"a- ii ~ I ' ~ :::.:::.:: ..:::: I \ / \ -~ l?- ,__ ? / I \ \ \ ......... ~' _.. '-.;\ I Unknown ~ / k: ~ V~~~ I\ j "t,' I \ ~ /'-. "N -' \., ~ '~ _,_:,, I\ i.-, ,, ~ ✓ .,::.. \ _;~ -✓- ~ -- -- \ l/ ~ "- ¾ -::-, --- I I I , \ ~L Unknown ~ < ' -- Number ofl I objects 1/- ~ .:.:_ '' 0 M ' \ I 38 0 ... 40 FIGURE - , \_ I - ,1/ I'- I ~-, ~- / , Vr\ ,/ \b< ~, ✓- ~ r:..:: ,, h.,v y ---~ ) ~ -- V-- ~ , Unknown 20 0 0 I V\ (' \Unkn~~ h 3§ C Cl> C ~-~~, "hf/,' .:.;:; ,._ Cl> -...... 0 ::.... I I I 20 C -- I ....... "'-:: IL ~ -- I "' 3§ ...0 (.) 60 <t a.... 40 ~ \ 60 I ~ "~~ \ I \ 3~ (.) ... 40 0 Unknown i..:::: ~ r 1/) I I I v' "' I ~ ~;' ::>< ~ I I I I I I I I I V I ~~~~be,f~~~~;,•b~ \,~(§;!~~aa:-~~:~-,~!:t;!~~~o~-e\,:~~e~~e~ ~-..,~~eb n~ ~,i~o~\o~ w; ~o' ~era,,,, , "- "'(,~~o I ~ ~ I,,.,. 0 ' Q~ Color ' I',.. ~ -.::: ~ f1/ ""' - ' Shape Speed I Duration 30 CHARACTERISTICS PROFILES OF OBJECT SIGHTINGS BY TOTAL SAMPLE, KNOWN EVALUATIONS, AND INDIVIDUAL KNOWN EVALUATIONS, WITH UNKNOWN EVALUATIONS SUPERIMPOSED B-7508 46 I I I I I ---------------------65" 40" ~ 35" --.J 30" KEY: IN EACH SUBDIVISION THE TOP FIGURE INDICATES THE FREQUENCY OF ALL SIGHTINGS, THE MIDDLE FIGURE UNIT SIGHTINGS, ANO THE BOTTOM FIGURE OBJECT SIGHTINGS 45' 115" FIGURE 31 FREQUENCY OF OBJECT, UNIT, AND ALL SIGHTINGS WITHIN THE UNITED STATES 1947-1952, BY SUBDIVISIONS OF ONE DEGREE OF LATITUDE AND LONGITUDE 1:11' ll!l" 110" 105° 100" BS0 90" 95" BO" 750 65" 111" CANADA 15" 411" 411" CENTRAL WEST 59-10°' ~ 00 35" 311" 25" 45° 1211" 115" FIGURE 32 105" 95" 911" BS" DISTRIBUTION OF OBJECT SIGHTINGS BY EVALUATION FOR THE TWELVE REGIONAL AREAS OF THE UNITED STATES, WITH THE STRATEGIC AREAS LOCATED (STRATEGIC AREAS WERE DETERMINED OH THE BASIS OF CONCENTRATION OF OBJECT SIGHTINGS) 65" 611" ---------------------6\0 Balance of Central East Region 81 object sightings ~ CD 36 FIGURE 33 COMPARISON OF EVALUATION OF OBJECT SIGHTINGS IN THE STRATEGIC AREAS OF THE CENTRAL EAST REGION a- 7511 10/5 43 1010 915 l ~ ~ \ ; ~ ~ \ r J\ L>l\ \ I 1 J (JI 0 I l 36 I 1010 FIGURE Balance of Central I Midwest Region I 164 object s i g h t i n g s , \ ) V ~,. \/ \ ( 915 34 COMPARISON OF EVALUATION OF OBJECT SIGHTINGS IN THE STRATEGIC AREAS OF THE CENTRAL MIDWEST REGION a-7512 I I I I I I I I I I I I I I I I I I I Farwest Region FIGURE 35 COMPARISON OF EVALUATION OF OBJECT SIGHTINGS IN THE STRATEGIC AREAS OF THE CENTRAL FARWEST REGION B-7515 I I I 51 1010 9\0 36 36 t I\ ~ 2\F J t1 UI N e2 object sightings 0 Waco 210 object sightings ICIO 9\0 8\5 FIGURE 36. COMPARISON OF EVALUATION OF OBJECT SIGHTINGS IN THE STRATEGIC AREAS OF THE SOUTH MIDWEST REGION B-7514 ---------------------10/5 1010 9 e object slvhtlnvs 36 Albuquerque • (11 (>I :) , 1010 FIGURE 37 COMPARISON OF EVAWATION OF OBJECT SIGHTINGS IN THE STRATEGIC AREAS OF THE SOUTH WEST REGION A-7515 Balance of South Farwest Region 19 object sightings FIGURE 38 COMPARISON OF EVALUATION OF OBJECT SIGHTINGS IN THE STRATEGIC AREAS OF THE SOUTH FARWEST REGION B-7516 54 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I __I This information consisted of: ( 1) Time and date of observation in Greenwich Civil Time (2) Latitude and longitude of the observer at the time of observation. Figure 39 shows a celestial sphere on which Z represents the ob­ server's zenith, ~ represents the sun, and N represents the north celestial pole. Using the date and time of the observation, the longitude and declina­ tion (§) of the sun were obtained from an ephemeris of the sun and corrected for the equation of time. The difference between the longitudes of the sun and the observer was taken, and called the hour angle (HA on Figure 39). Then, using the declination of the sun (S), the latitude of the observer (lat), and the hour angle (HA), the angle (ZS)between the observer's zenith and the sun can be calculated from the law of cosines of spherical trigo­ nometry. Thus, cos ZS = cos (90 - lat) cos (90 - S) + sin (90 - lat) sin (90 - S) cos (HA). Since the angle ZS is measured from the observer's zenith, the angle of elevation of the sun above the horizon for daytime sightings was found by taking 90 - ZS. When the sun was below the horizon, the angle of depres­ sion of the sun below the horizon was found by taking ZS - 90. Having found the angle ZS, the bearing of the sun ( angle B} was ob­ tained from the formula: sin (B) = sin(90-S) sin (HA) sin (ZS} All of the above calculations were made with IBM equipment. Sines, cosines, and their inverses were obtained from a deck of 9,000 IBM cards on which seven-place Peter 1 s tables of the sines, cosines, and tangents of angles had been punched for each 0.01 of a degree ·from O to 90 degrees. Upon completion of these calculations, the cards representing OBJECT SIGHTINGS were sorted on the sign of the sine of the bearing angle. This separated the cards into two groups: ( 1) sightings which occurred between noon and midnight, for which the sine of the bearing angle was positive; and (2) sightings between midnight and noon, for which the sine of the bearing angle was negative. Then each of these groups was sorted into groups for intervals of 10° in angle of elevation of the sun from -90° to +90°. A count was made of the number of cards in each group and from this a histogram was constructed (Figure 40}. The UNKNOWN OBJECT SIGHTINGS were then sorted out, counted in the same manner, and a histogram was made (again see Figure 40). 55 FIGURE 39 DIAGRAM OF A CELESTIAL SPHERE A· 75 35 56 I I I I I I I I I I I I I I I I I I I I I I ~--------------------300 275 250 I 225 I Sun~t Cl) -0 C I 200 I I .s: 0 en u 175 Cb 150 ...... .0 - 125 Cb .0 100 0 All object sightings ------+--41► (710 __, "- I I I z Unknown object sightings I E ::::, I • Sun,I rise 75 I I I I I I I 50 J 25 0 I I I -90 -60 -30 0 +30 +60 +90 +60 +30 0 -30 -60 Angle of Elevation of The Sun Fl GURE 40 FREQUENCY OF OBJECT SIGHTINGS BY ANGLE OF ELEVATION OF THE SUN, INTERVALS OF 10 DEGREES OF ANGLE A-7536 -90 The following points should be carefully noted about these histograms: ( 1) The negligible number of sightings when the sun is within 10° of the zenith and nadir (angle of elevation of the sun = ± 90 °) of the observer is due to the fact that the southernmost latitude of the U. S. is greater than the declination of the sun at the summer solstice, so that it would be impossible for the sun to reach the zenith or nadir of any observer in the U. S. (where most of the sightings were made). (2) The time of day at which a particular angle of elevation of the sun occurs does not remain fixed but varies from day to day. Consider, for example, the variation in sunrise and sunset times over the course of a year. Thus, there are only two inferences to be made from this histogram: ( 1) the high peak of sightings soon after sunset, and (2) the lack of increase in the UNKNOWNS relative to the KNOWNS near either sunset or sunrise. This would seem to discount the possibility that atmospheric phenomena such as mock suns were the primary cause of the unknown reports, since such phenomena usually occur when the sun is near the horizon. The Local Sun Time was computed as a step in the calculation of the angle of elevation of the sun. It is related to the hour angle by the equation: Local Sun Time (L. S. T.) = HA/15 + 12. 00, where L. S. T. is in hours and HA in degrees. The cards were grouped on the basis of L. S. T. in intervals of one hour, and the number of cards in each interval was counted. Again the UNKNOWNS were sorted out and similarly treated. Histograms were con­ structed with the results of these tabulations of OBJECT SIGHTINGS (Figure 41). Here, again, there is a peak in the early evening hours. The cards were then broken up into seven groups on the basis of the angle of elevation of the sun, as follows: Group 1 - Daylight sightings for which the sun was more than 10° above the horizon. Group 2 - Sunset sightings for which the sun was between 0° and 10° above the horizon. Group 3 - Sunset sightings for which the sun was between 0° and 10° below the horizon. Group 4 - Evening sightings for which the sun was between 10° and 40° below the horizon. 58 I I I I I I I I I I I I I I I I I I I I I I ---------------------300 275 250 & 225 ---en-a, 200 C +- +0 a., 175 - 150 Midnight ·-..0 0 ~ 0 (JI CD ~ a., ..0 E :, z Noon 125 I 100 75r All object sightings L ,_ I I I I :Midnight I I I I I Unknown ;.bject sightings ~ ~ 50 25 0300 0600 0900 1200 1500 1800 2100 2400 Loco I Sun Time FIGURE 41 FREQUENCY OF OBJECT SIGHTINGS BY LOCAL SUN TIME, INTERVALS OF ONE HOUR A-7537 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 O0 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 Angle of Elevation Group Identification 1 2 3 4 5 6 7 Balloon Astronomical Aircraft Light phenomena Insufficient information UNKNOWN Other 156 52 187 8 72 134 64 17 6 23 2 12 14 8 28 43 49 4 26 25 12 83 236 144 25 76 150 50 40 118 60 7 28 86 36 0 9 5 0 2 6 3 2 6 2 0 0 7 7 Total 673 82 187 764 375 25 24 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 60 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I UNKNOWNS in each characteristic group showed the same general trend. In other words, on the basis of these graphs, it looked as though there was a good possibility that the UNKNOWNS were no different from the KNOWNS, at least in the aggregate. It was decided to investigate this by the use of a statistical procedure called the "Chi Square Test". The Chi Square Test is a statistical test of the likelihood that two distributions come from the same population, that is, it gives the proba­ bility that there is no difference in the make-up of the two distributions being measured. The method is outlined as follows: ( 1) Adjust the distributions by multiplying the KNOWNS in each characteristic group by the ratio of the total number of UNKNOWNS to the total number of KNOWNS. (The Chi Square Test is applicable only to distributions which have the same total number of elements.) (2) Take the difference between the number of UNKNOWNS and the adjusted number of KNOWNS in each characteristic group. (3) Square the remainder from Step 2. ( 4) Divide the result of Step 3 by the corresponding number of adjusted KNOWNS. This is the chi square for the particular group. Summing the indi­ vidual chi squares over the groups of a characteristic gives the chi square for that characteristic. This number is then compared with a table of the distribution of chi square which can be found in many texts on elementary s tatis tics. It will be noted that chi square is tabulated in terms of degrees of freedom which in this case is one less than the number of groups of sight­ ings for each characteristic. The tabulations of KNOWNS and UNKNOWNS against the six char­ acteristics and the Chi Square Test as it was applied are shown in Tables II through VII. In each case, the number of degrees of freedom is given, as is the value of chi squares corresponding to probabilities of 5 per cent and 1 per cent that two distributions with this number of degrees of freedom come from the same population. Since the greater the value of chi square the smaller the probability of homogeneity of two distributions, a calculated value of chi square greater than either the 5 per cent or 1 per cent values will indicate a probability less than 5 per cent or 1 per cent, respectively, that the two distributions are homogeneous. The term homogeneity is used here to indicate that two distributions could have come from the same population. 61 TABLE II CHI SQUARE TEST OF KNOWNS VERSUS UNKNOWNS ON THE BASIS OF COLOR x2 Color Number of KNOWNS Adjusted Number of KNOWNS (K) Number of UNKNOWNS (n) (K-n)2 K White Metallic Not stated Orange Red Yellow Green Blue Other 405 313 209 172 146 128 130 67 195 100 77 51 42 36 31 32 17 48 112 76 62 49 33 31 14 26 31 1. 44 0. 01 2.37 1. 17 0.25 0 10. 13 4. 76 6.02 Total 1765 434 434 26. 15 Degrees of freedom 8 15.5 20. 1 I I I I I I I I I I I I I I I I I I I I 62 I I I I I I I I I I I I I I I I I I I I I TABLE III CHI SQUARE TEST OF KNOWNS VERSUS UNKNOWNS ON THE BASIS OF NUMBER Number of KNOWNS Adjusted Number of KNOWNS (K) Number of UNKNOWNS (n) x2, (K-n)2 K 1 2 3-10 11 or more Not stated 1339 159 185 41 41 329 39 46 10 10 297 37 70 25 5 3. 11 o. 10 12. 52 22. 50 2.50 Total 1765 434 434 40.73 Number of Objects Per Sighting Degrees of freedom 4 9.5 13.3 I I I 63 TABLE IV Shape CHI SQUARE TEST OF KNOWNS VERSUS UNKNOWNS ON THE BASIS OF SHAPE Number of KNOWNS Adjusted Number of KNOWNS {K) Number of UNKNOWNS (n) x2 {K-n}' 2 K Elliptical Rocket and aircraft Meteor or comet Teardrop, lenticular, or conical Flame Other Not stated 838 80 55 103 206 20 14 25 195 33 4 22 0.59 8.45 7. 14 0.36 96 193 400 24 47 98 10 54 116 8. 17 1.04 3.30 Total 1765 434 434 29.05 6 Degrees of freedom 5% 12.6 16.8 1% 64 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I TABLE V CHI SQUARE TEST OF KNOWNS VERSUS UNKNOWNS ON THE BASIS OF DURATION OF OBSERVATION Duration of Observation Number of KNOWNS Adjusted Number of KNOWNS (K) Number of UNKNOWNS (n) x2 {K-n}' 2 K 5 sec or less 6-10 sec 11-30 sec 31-60 sec 61 sec-5 min 6-30 min Over 30 min Not stated 259 92 153 108 269 305 135 444 64 23 38 26 66 75 33 109 27 21 33 42 99 71 37 104 21.39 o. 17 0.66 9.85 16.50 0.21 0.48 0.23 Total 1765 434 434 49.49 Degrees of freedom 7 5% 14. 1 18. 5 1% I I I 65 TABLE VI CHI SQUARE TEST OF KNOWNS VERSUS UNKNOWNS ON THE BASIS OF SPEED x2 ,2 Speed Number of KNOWNS Adjusted Number of KNOWNS (K) Stationary Less than 100 mph 100 to 400 mph Over 400 mph Meteor-like Not stated 249 154 181 403 83 695 61 38 45 99 20 171 53 26 58 145 16 136 1. 05 3.79 3.76 21. 37 0.80 7. 16 Total 1765 434 434 37. 93 Degrees of freedom Number of UNKNOWNS ( n) {K-n) K 5 5% 1% 11. 1 15. 1 I I I I I I I I I I I I I I I I I I I I 66 I I I I I I I I I I I I I I I I I I I I I I I I TABLE VII CHI SQUARE TEST OF KNOWNS VERSUS UNKNOWNS ON THE BASIS OF LIGHT BRIGHTNESS Light Brightness x2 Number of KNOWNS Adjusted Number of KNOWNS (K) Number of UNKNOWNS (n) (K-n)' 2 K 47 151 76 11 37 19 14 28 16 0.82 2. 19 0.47 Sunlight on mirror Sunlight on aluminum Sunlight on plaster, stone, or soil Brighter than moon Like moon or duller than moon Not stated 273 68 67 17 61 22 0.55 1. 47 1150 283 293 0.35 Total 1765 434 434 5.85 Degrees of freedom 5 5% 1% 11. 1 15. 1 67 In five of the six cases, the probability is less than 1 per cent that the distributions are the same. In the sixth case, Light Brightness, the classifications are too nebulous to be of real value. However, these tests do not necessarily mean that the UNKNOWNS are primarily "flying saucers" and not aircraft, balloons, or other known objects or natural phenomena. The UNKNOWNS might still be unidentified KNOWNS if either of the follow­ ing cases occurred: ( l} The characteristics which were observed for the UNKNOWNS were different from those observed for the KNOWNS because of the psychological make-up of the observer or because of atmospheric distortion. This assumes the distribution of objects in KNOWNS and UNKNOWNS is the same. (2) The UNKNOWNS may be known objects in different propor­ tions than the group identified as KNOWNS. (That is, a greater percentage of the UNKNOWNS could be aircraft than the percentage of aircraft in the identified KNOWNS.} The second case is the more probable one. In this connection, it is interesting to note the factors which contributed to a large chi square result in the tests made above: (1) Color The major contribution to chi square in color is from the color green. There is a large excess of green sightings among the KNOWNS over the UNKNOWNS. Of the 130 known objects in this classification, 98 are astronomical, and are due mostly to the green fireballs reported from the Southwest U. S. (2) Number The large chi square is due to a greater proportion of UNKNOWNS in the multiple object classification. Apparently these are harder to identify. (3} Shape In this case, there is a higher percentage of UNKNOWNS in the rocket-aircraft-shape classification. These might be familiar objects for which unusual maneuvers were reported. There is a higher percentage of KNOWNS in the flame and in the meteor- or comet-shape category, which in both cases appears to result mainly from excesses of astronomical sightings. 68 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I (4) Duration of observation Here there is an excess of KNOWNS in the less-than5-second group. Again, the majority of KNOWNS in this group are astronomical. The grea