you can check the map on here… seen if any are close by… tho in some cases you might just get your national isp main datacenter address…
http://storjnet.info/
another easy way is to compare ingress… ingress is very accurately divided between ip/24 subnets, thus if you know what ingress has been for a certain day, then you can see if its 1/2 then there is two nodes on the network… 1/3 and there is 3… so on and so forth…
you should on most days be able to distinguish somewhere between 19-20 and even 39-40 nodes on a network… by this rather crude method… because ingress is highly accurate if the node has no limitations or issues…
we have a bandwidth thread going where people post dashboard screen shots.
this is my node which is usually a fairly accurate measure…
so your total ingress for the 13th should be about 36 GB … if you get 15-17GB total ingress then there will be a second node on your ip/24 subnet …
total ingress is(normal + repair else it will not be accurate)