Since it is not obvious from the title, clarifying that this is astronomy related. Some more context: Nine point sources appeared within half an hour on a regi

Since it is not obvious from the title, clarifying that this is astronomy related. Some more context: Nine point sources appeared within half an hour on a region within ∼ 10 arcmin of a red-sensitive photographic plate taken in April 1950 as part of the historic Palomar Sky Survey.