Can pubsubhubbub be used to have a check on other's public repositories?

It did worked with my own repositories but not with others repo. Response says 

“No repository found for hub.topic: “https:\github…””

I have generated a personal token as well

curl -H “Authorization: token 88d8c0d2610…” \
-F “hub.mode=subscribe” \
-F “hub.topic=” \
-F “hub.callback=

If you haven’t already, please contact us at with the info so we can look into that further.