They are photographic plates, then vs. now. This cannot be dismissed as simple user error. Especially in 1950 where we did not have to contend with this massive

They are photographic plates, then vs. now. This cannot be dismissed as simple user error. Especially in 1950 where we did not have to contend with this massive population of artificial satellites. Other solutions must be sought. What is not clear to me is whether one can find these missing stars on other plates taken at a later time. If so, then this lends credence to some sort of stellar phenomenon. The paper rules out asteroids due to the long exposure times of the images, which would have turned any objects moving in our solar system into a smear rather than a point source.