Correspondence from Försvarsstaben to Professor Bertil Lindblad regarding celestial phenomena

This document is a letter dated June 26, 1946, from Major Nils Ahlgren of the Swedish Defense Staff's Air Defense Department to Professor Bertil Lindblad of the Stockholm Observatory. The correspondence addresses a series of sightings of 'celestial phenomena' reported across Sweden since late May 1946. The military initially considered the possibility that these sightings were related to high-altitude rockets, similar to those deployed during the latter part of the World War. However, after compiling reports from newspapers and military channels, the Air Defense Department concluded that the rocket hypothesis was unlikely. The primary reasons for this skepticism were the reported flight characteristics, specifically a 'zigzag' course and a 'very low speed,' which the military noted were inconsistent with typical rocket behavior, though they acknowledged that radio-controlled rockets might theoretically exhibit such traits. The letter notes that reports are highly uncertain regarding timing, altitude, and direction, making it difficult to determine if the sightings represent a single phenomenon. Because some sources, particularly in Finland, suggested the phenomena might be meteorites, the military sought the Professor's expert opinion on the matter. Finally, the letter instructs that the enclosed summary of reports is to be treated as confidential to prevent providing information to potential experimenters.