pm - the NRO L-38.
You can watch it live here. But the deal is, you aren't allowed to tell anyone, because it has a secret payload for the National Reconnaissance Office.
They are the same mob who just handed two unwanted duplicates (with improvements) of the Hubble Space Telescope to NASA!
So space telescopes even better than Hubble - which has been the groundbreaking force in astronomy science for the last decade - were deemed no longer any good for the NRO's spying requirements. One can only wonder at the quality of the device that they are launching today instead!
And of course, what could that payload do for us all if it were turned to science instead of spook work? Sigh...
Anyway, those considerations aside, sit back, turn up the volume, and enjoy the launch. It will be quick though - as the commentator has already said, the broadcast will - at the request of "the client" - be terminated at the point the payload fairing is jettisoned.