When is hackathon and submission deadline?

The Rules page is ambiguous.

Under Eligibility it says that all hacking development must take place during the official hackathon window: September 5 to September 7. Earlier on the Rules page it describes the hackathon event as taking place on September 19 to September 21.

It also says in the rules that all submissions must be made before September 21 at 4:00pm "sharp," but then it says the submission deadline is September 21 at 5:00pm PST (is that a spongy deadline).

Please clarify. Thank you.