Very bright spot, only shows up on 1 exposure in 2013.
No hits in the MP database.
Looking at the single exposures, the 2014 run ALSO picked up something in the same area.
Also no hit in the MP database.
I think these weird squarish-shaped things are some kind of glint. I think they’re always near the edge of the chip, in relatively early exposures (low exposure number), because later they added some internal baffling to the camera to prevent this light path.
okay, it does look too bright to be undiscovered; but you never know 
I thought the square form might have been due to the post processing you guys run on the pictures.
Hard to tell if they’re actually squarish or if they just have such thick diffraction spikes that they appear that way.
There is some kind of residual trace in there, but it doesn’t show up on the other stars though. It is placed in a perfect 45° angle, like the spider vanes, so must indeed be some kind of artefact.
Yes, if you look in the individual exposures you’ll see that one of those squarish artifacts appears in one of the exposures but it’s almost entirely masked out.