Within UFOCAT
Why UFOCAT Intentionally Keeps Duplicate UFO Records
Details why UFOCAT deliberately preserves duplicates for one event across different sources and witnesses.
On this page
- One event, multiple publications
- Multiple witnesses for a single object
- Indirect and uncertain source chains
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Introduction
Within Center for UFO Studies’ flagship sighting database UFOCAT — the UFO Catalogue — researchers will often encounter several entries that refer to the same underlying event. This is not an accidental artefact of sloppy data entry, but a deliberate design choice anchored in the catalogue’s mission. UFOCAT preserves duplicate records for what might appear to be one sighting in order to map how that incident has been reported, investigated, published and re‑reported across multiple sources. Understanding why UFOCAT intentionally keeps duplicates is central to using the catalogue as a tool for source tracing rather than as a strict count of unique incidents. [Center for UFO Studies]cufos.orgCenter for UFO StudiesUFOCATUFOCAT is a catalog of published and unpublished UFO sighting reports. It often contains multiple entries for…
One Event, Multiple Publications
One of UFOCAT’s core principles is to capture every distinct published account of a sighting, not just a single abstracted event. This means that if an original local investigation file, a later journal article, and a book chapter all describe the same sighting, UFOCAT will include separate records for each. Each entry points back to its direct source and often to an indirect source, using coded fields to identify the publication, investigator, date and page details. [Center for UFO Studies]cufos.orgCenter for UFO StudiesUFOCATUFOCAT is a catalog of published and unpublished UFO sighting reports. It often contains multiple entries for…
This approach serves two purposes:
- Bibliographic completeness: It preserves a trail of how that event has been documented or interpreted in different venues — essential for scholars tracing how narratives evolve over time.
- Source transparency: It retains the ability to assess the quality, reliability and independence of each source rather than conflating them into a single “canonical” account.
In practice, this means UFOCAT is a catalogue of sources about sightings, not a de‑duplicated incident list. Researchers who want a strict count of unique incidents must filter out secondary entries using fields like the X2 primacy flag. [Center for UFO Studies]cufos.orgCenter for UFO StudiesUFOCATUFOCAT is a catalog of published and unpublished UFO sighting reports. It often contains multiple entries for…
Multiple Witnesses and Composite Accounts
Another rationale for duplicate records stems from the witness structure of many UFO reports. In older case files and periodical accounts, a single sighting event might be documented by multiple witnesses independently. Sometimes investigators filed separate narrative reports for each witness, which were later absorbed into UFOCAT without collapsing them into one. Rather than discarding this multiplicity, UFOCAT preserves each witness‑centred perspective as a separate record, because:
- it may retain descriptive details unique to each witness (e.g. object features or timeline discrepancies), and
- it provides a window into how multiple independent accounts relate to the same event.
This mirrors archival practice in other historical domains, where multiple source variants for one incident are maintained so that researchers can compare differences and assess reliability. Although modern data systems sometimes unify such instances into one canonical record, UFOCAT deliberately leaves these separate in part because it emphasises preserving original source fidelity over forced unification. [Center for UFO Studies]cufos.orgCenter for UFO StudiesUFOCATUFOCAT is a catalog of published and unpublished UFO sighting reports. It often contains multiple entries for…
Indirect and Uncertain Source Chains
UFOCAT also captures cases where the connection between a report and an original event is indirect or uncertain. Many older sightings were first published in local newspapers, later reprinted in UFO periodicals, and subsequently summarised in books. Each of these acts of transmission is treated as a unique source node in UFOCAT’s structure, even if all describe the same underlying phenomenon.
The catalogue uses fields such as SOURCE, ISOURCE, PRN, X2 and IRN to distinguish between direct and indirect sources and to maintain blocks of related records. A block of records describes all of the sources associated with a single incident, and the primary record number (PRN) points to the version judged most original. Other entries remain because they provide bibliographic or contextual value even though they might be chronologically later or less complete. [Center for UFO Studies]cufos.orgCenter for UFO StudiesUFOCATUFOCAT is a catalog of published and unpublished UFO sighting reports. It often contains multiple entries for…
This mechanism acknowledges that:
- information can be layered — authors may add commentary, inference, or editorial framing that differs slightly from the original report;
- source provenance matters — knowing whether an account came from an official investigation file, a lay journalistic retelling, or a retrospective book matters for assessing its evidential weight;
- historical signal is in variants — differences between publications about the same event can reveal how narratives evolve or how errors propagate.
Rather than suppressing these variants, UFOCAT retains them to document the trail of sources with as few editorial interventions as practical. [Center for UFO Studies]cufos.orgCenter for UFO StudiesUFOCATUFOCAT is a catalog of published and unpublished UFO sighting reports. It often contains multiple entries for…
Balancing Completeness and Usability
The intentional presence of duplicate records means that raw record counts in UFOCAT overstate the number of individual sightings — a frequent point of confusion for new users. CUFOS documentation explicitly cautions that simple case tallies without primacy filtering can be misleading, because many incidents appear multiple times due to their presence in several sources. [Center for UFO Studies]cufos.orgCenter for UFO StudiesUFOCATUFOCAT is a catalog of published and unpublished UFO sighting reports. It often contains multiple entries for…
For researchers interested in unique event counts, UFOCAT includes structural markers to isolate primary entries and to collapse linked blocks into a single conceptual case. But for those focused on historical research, bibliographic provenance or source criticism, the duplicate entries are the very point of the catalogue. They make UFOCAT a tool for mapping how UFO knowledge has been transmitted and transformed through different media and investigators.
In this sense, duplicates are not errors to be eliminated but essential metadata that:
- record where and how the sighting was reported,
- allow scholars to evaluate the chain of evidence, and
- expose the network of publications and witnesses connected to each incident. [Center for UFO Studies]cufos.orgCenter for UFO StudiesUFOCATUFOCAT is a catalog of published and unpublished UFO sighting reports. It often contains multiple entries for…
Risks and Critiques
The deliberate retention of duplicates has drawn criticism, particularly from quantitative analysts who treat UFOCAT like a simple incident database. Without careful filtering, users can overcount sightings or misinterpret trends. This underlines a broader data quality tension: preserving rich source detail inevitably introduces redundancies that complicate large‑scale statistical analysis.
However, proponents argue that suppressing duplicates in favour of artificial unification would sacrifice the very provenance information that gives UFOCAT its scholarly value. Effective use of the catalogue therefore hinges on understanding its design philosophy — one that prioritises source traceability over deduplication — and applying appropriate filters or expert judgement when counting events. [Center for UFO Studies]cufos.orgCenter for UFO StudiesUFOCATUFOCAT is a catalog of published and unpublished UFO sighting reports. It often contains multiple entries for…
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Further Reading
Books and field guides related to Why UFOCAT Intentionally Keeps Duplicate UFO Records. Use these as the next step if you want deeper reading beyond the article.
The Hynek UFO Report
Useful background for catalogue-based UFO research and case classification.
The UFO Experience
Discusses multiple sources for a single sighting and the methodology of documenting duplicates.
UFOs
Illustrates the importance of multiple reports and intentional duplication in official records.
UFOs : Generals, Pilots, and Government Officials Go on the R...
First published 2011.
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Endnotes
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Source: cufos.org
Link: https://cufos.org/cufos-publications-databases/ufocat/Source snippet
Center for UFO StudiesUFOCATUFOCAT is a catalog of published and unpublished UFO sighting reports. It often contains multiple entries for...
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Source: cufos.org
Title: UFOCAT Codebook 2023
Link: https://cufos.org/PDFs/UFOCAT%20Codebook%202023.pdfSource snippet
Center for UFO StudiesUFOCAT 2023June 6, 2024 — It exists today as the most comprehensive reference tool and bibliographic source on UFO...
Published: June 6, 2024
Additional References
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Source: pmc.ncbi.nlm.nih.gov
Title: Previous work on duplicate detection has acknowledged that expert curation is th
Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC5225397/Source snippet
nih.govDuplicates, redundancies and inconsistencies in the primary nucleotide databases: a descriptive study - PMCJanuary 10, 2017 — DUPL...
Published: January 10, 2017
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Source: academia.edu
Link: https://www.academia.edu/71337593/UFOs_and_the_extraterrestrial_contact_movement_a_bibliographySource snippet
(PDF) UFOs and the extraterrestrial contact movementWhatever the explanation for UFO sightings, whether alien spacecraft or something mor...
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Source: researchgate.net
Link: https://www.researchgate.net/publication/371163445_The_Scientific_Investigation_of_Unidentified_Aerial_Phenomena_UAP_Using_Multimodal_Ground-Based_ObservatoriesSource snippet
(PDF) The Scientific Investigation of Unidentified Aerial...[1972] \Education and the UFO Phenomenon," UFOs: A Scienti¯c Debate (The Nor...
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Source: sciencedirect.com
Link: https://www.sciencedirect.com/science/article/pii/S1672022920300632Source snippet
ScienceDirectApril 1, 2020 — Perspective Quality Matters: Biocuration Experts on the Impact of Duplication and Other Data Quality Issues...
Published: April 1, 2020
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Source: blog.core.ac.uk
Title: detecting duplicate records and manuscript versions in your repository
Link: https://blog.core.ac.uk/2023/08/22/detecting-duplicate-records-and-manuscript-versions-in-your-repository/Source snippet
duplicate records and manuscript versions in your repository – COREAugust 22, 2023 — DETECTING DUPLICATE RECORDS AND MANUSCRIPT VERSIONS...
Published: August 22, 2023
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Source: academic.oup.com
Title: However, this work has only limited relevance for bioinformati
Link: https://academic.oup.com/database/article/doi/10.1093/database/baw164/2870676Source snippet
for measurement of duplicate detection methods in nucleotide databases | Database | Oxford AcademicJanuary 8, 2017 — BACKGROUND In the co...
Published: January 8, 2017
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Source: youtube.com
Title: “100,000 UFOs Are Surrounding Earth!” ft. Top Astronomer Beatriz Villarroel
Link: https://www.youtube.com/watch?v=1zRWi_r3HRMSource snippet
Jacques Vallee UFO database data analysis presentation A Forgotten UAP Event and Its Ramifications for the Science of the Phenomenon, wit...
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Source: oclc.org
Title: Leveraging machine learning for World Cat de-duplication
Link: https://www.oclc.org/en/news/announcements/2023/leveraging-machine-learning-for-worldcat-de-duplication.htmlSource snippet
Leveraging machine learning for WorldCat de-duplicationAugust 14, 2023 — LEVERAGING MACHINE LEARNING TECHNOLOGY AS PART OF ONGOING WORLDC...
Published: August 14, 2023
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Source: pharmagmp.in
Title: why duplicate records can invalidate your entire batch
Link: https://www.pharmagmp.in/why-duplicate-records-can-invalidate-your-entire-batch/Source snippet
Pharma GMPNovember 14, 2025 — WHY DUPLICATE RECORDS CAN INVALIDATE YOUR ENTIRE BATCH November 14, 2025November 14, 2025 digi Why Duplicat...
Published: November 14, 2025
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Source: delpha.io
Title: Duplicates: The Bane of Data-driven Companies
Link: https://delpha.io/blog/duplicates-the-bane-of-data-driven-companies/Source snippet
DelphaOctober 3, 2022 — DATA QUALITYDUPLICATESMACHINE LEARNING DUPLICATES: THE BANE OF DATA-DRIVEN COMPANIES Germain Bourgeois Published...
Published: October 3, 2022
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