A L-1011 Tristar Aircraft took off from the Kwajalein Atoll today at 15:00 UTC with a Pegasus Rocket strapped to the belly. In the Pegasus rocket NASA's X-Ray Observatory NuSTAR sits awaiting launch.
Launch is set to occur at 16:00 UTC when the rocket will drop from the aircraft for 5 seconds before the first stage will ignite.