Core booster burnout and Centaur first burn Centaur separation Time: 4 minutes, 44 seconds Time: 4 minutes, 28 seconds and Payload fairing jettison 4 minutes, 34 seconds Time: 3 minutes, 23 seconds Solid booster burnout and jettison Time: 1 minute, 47 seconds (SRBs 1–2) and 1 minute, 48 seconds (SRBs 3–4–5) Launch Milestones Liftoff through Centaur First Burn Ignition/Liftoff Times approximate for Jan. 17 launch 27