  Nine point sources appeared within half an hour on a region within $\sim$ 10
arcmin of a red-sensitive photographic plate taken in April 1950 as part of the
historic Palomar Sky Survey. All nine sources are absent on both previous and
later photographic images, and absent in modern surveys with CCD detectors
which go several magnitudes deeper. We present deep CCD images with the
10.4-meter Gran Telescopio Canarias (GTC), reaching brightness $r \sim 26$ mag,
that reveal possible optical counterparts, although these counterparts could
equally well be just chance projections. The incidence of transients in the
investigated photographic plate is far higher than expected from known
detection rates of optical counterparts to e.g.\ flaring dwarf stars, Fast
Radio Bursts (FRBs), Gamma Ray Bursts (GRBs) or microlensing events. One
possible explanation is that the plates have been subjected to an unknown type
of contamination producing mainly point sources with of varying intensities
along with some mechanism of concentration within a radius of $\sim$ 10 arcmin
on the plate. If contamination as an explanation can be fully excluded, another
possibility is fast (t $<0.5$ s) solar reflections from objects near
geosynchronous orbits. An alternative route to confirm the latter scenario is
by looking for images from the First Palomar Sky Survey where multiple
transients follow a line.
