This show is independently distributed to public television stations as a fundraising special. So, broadcast will vary depending on when the local station schedules pledge week and how it calculates its audience. But Sunday for the Bay Area is pretty cool for the folks out there!
As I have read, these kinds of programs are independently distributed, offered in abridged form (with mock pledge breaks) for free to local stations. Stations then have to purchase materials given as premiums. These are sold at a low rate, but high enough to offer a bulk profit to the producers.