Oh yeah, that is interesting. I would guess an artifact from the pictures. Maybe those are the lines where they joined the different pictures together into 1 picture. I would think they could do a better job than that though.
You can, somehow, view this # in the magnetic field map picture too. First I thought this was an artifact, but I highly doubt that they would leave such an amateur thing behind (and even amateurs don't get tricked into this). Besides from the visible picture and magnetic map, I don't seem to find any correlation with the other pictures.