You can’t really tell who is using a cable without access to quite a bit of contractual data.
Cable capacity is generally leased as strands, then subleased as waves, then someone leases L2 circuits on top of that. Not like L3 where you can run a traceroute or whatever, though I wonder if you could determine possible cables based on latency…
You can pick up clues from router names and domains. For instance if I try traceroute riotimesonline.com I can see routers with "telehouse" in the name (telehouse being the big London interconnect), then a couple of "atlas.cogentco.com" routers, one of which ("lon13") has 10ms ping, and the next ("bos01") has 77ms ping. The next hop seems to be to Amazon Data Services in Boston, so presumably the riotimesonline.com site is being served by AWS out of there, or at least it is for people not in Rio. That tells you who is leasing the transatlantic service. Unfortunately I can't instantly find a web server in Rio to ping.
> connecting Brazil to Europe in less than 60ms of latency
Wow that would be awesome when it's fully operational. I sure hope we in the southeast asia region had that kind of latency to both europe and america (both are around 200ms from here).
Any ideas how can I track the progress of each ASN in using it?