What is the quiescent magnitude of the X-ray nova V616 Mon? Could it be around 17.5 or are we seeing a close companion?
There is a 20.8 Vmag. star 6" to the NNE of the variable but if it is not resolved, it will only add up 0.07-0.10 mag. at the range 17.8-18.3 for V0616 Mon at quiescence.
Yes, V0616 Mon is around V= 18.0 at minimum.
I have updated VSX with this information and also added a remark for VSP about the companion, although I don't think it will be a problem. If you get as faint as V= 18, then you will be able to solve the two.
American Association of Variable Star Observers