Project Blue Book case 1501:
The case occurred on July 16, 1952, at Salem in Massachusetts, USA.
At 09:35 A.M., the witness, Shell Alpert, took this picture of four roughly elliptical blobs of light in formation through the window of his photographic laboratory. Alpert was a Coast Guard seaman assigned to the base in nearby Salem, MA. This photo has appeared numerous times in the Salem (MA) Evening News.
The first analysis by US Air Force's Project Blue Book concluded it was "probably" a double exposure hoax.
A second analysis by Blue Book concluded that it was "probably" reflections of street lamps on a window.
Finally, Project Blue Book considered the case "unexplained".