Others are starting their own launch threads and ought to come over to the LIVE THREAD here.
I’ll do a post with a link
spaceflightnow.com
2203 GMT (6:03 p.m. EDT)
The ground pyro initiator controllers (PICs) are scheduled to be powered up around this time in the countdown. They are used to fire the solid rocket hold-down posts, liquid oxygen and liquid hydrogen tail service mast and external tank vent arm system pyros at liftoff and the space shuttle main engine hydrogen gas burn system prior to engine ignition.
The shuttle’s two Master Events Controllers are being tested. They relay the commands from the shuttle’s computers to ignite, and then separate the boosters and external tank during launch.
Lots of fire stuff