I don't wish to spoil Guide's thunder, but the main source of world-wide asteroid occultation predictions is the site operated by Steve Preston of IOTA.  See...

Steve uses Dave Herald's Occult software.

Mostly these predictions are kept up do date and sorted for your site by using the Occult Watcher app.

where world wide users announce intentions to observe and others can see the approximate location of others in the team.

Regards

DaveGee

www.kuriwaobservatory.com