I noticed that in the same position of the transient AT2016gkj there is a starlike object in old plates as POSSI, POSSII and otres. The study of those plates seems to indicate that this object is variable (bright in the Epoch 1952,569 and very faint in Epoch 1989,564). Probably it is a recurrent object (NR or similar). See the attached image.
Best regards.
Rafael Benavides
I observed this transient the night after Rafael Benavides did it and I confirm his measurement and the same view of this transient in old plates. Regards.