Project SIGN and Project GRUDGE Incident Reports and Evaluations

This document is a comprehensive compilation of incident reports and evaluations related to Unidentified Flying Objects (UFOs) or Unidentified Aerial Phenomena (UAP), primarily occurring in July 1947. The reports originate from various locations, including Muroc Army Air Field in California, Harmon Field in Newfoundland, and other sites. The document serves as a record for Project SIGN and Project GRUDGE, the early U.S. Air Force efforts to investigate these phenomena. The reports are structured as checklists, providing details such as date, time, location, observer information, and physical characteristics of the objects observed. Many reports include remarks from the observers and subsequent evaluations by intelligence officers. A significant portion of the document is dedicated to the 'Incident Index,' which categorizes sightings based on Dr. J. Allen Hynek's evaluations. These categories include 'Astronomical' (high or low probability), 'Non-astronomical but suggestive of other explanations' (balloons, aircraft, rockets, flares, or miscellaneous reflections), and 'Non-astronomical, with no explanation evident.' The document highlights the challenges in identifying these objects, noting that many reports are likely the result of misinterpreting real stimuli, such as weather balloons, meteors, or conventional aircraft under unusual lighting conditions. Psychological factors, including the inability to accurately estimate speed, distance, and size, are also identified as contributing to the reports. The document includes correspondence between various military commands, such as the Air Materiel Command and the Air Defense Command, regarding the processing of these reports and the handling of photographic evidence, such as Kodachrome film. The tone of the document is analytical and administrative, reflecting the military's attempt to systematically categorize and explain the influx of UFO reports during this period. It emphasizes that while some incidents remain unexplained, there is no evidence to suggest a common pattern or origin for the sightings, and many can be explained through rational, scientific, or psychological means.