2:37 pm: Launch time just got bumped from 2:53 local to 3:24:30 local
2:48 pm: Flight event timer
T -0:07 Commence primary ignition
+0:00 Vehicle release and liftoff; all three RS-68s at full thrust
+0:44 Center stage throttles back to 55%
+1:31 Max Q; coincident with transition to supersonic flight
+4:00 Booster engine throttle-back to minimum
+4:02 BECO: booster engine cutoff
+4:04 Booster stages separate, core stage throttle-up to 102%
+5:28 MECO: main engine cutoff
+5:30 Staging
After that I doubt I will have eyes on it.
3:13 pm: L minus 12 minutes
3:17 pm: L minus 9 minutes. A bit of launch time creep apparently
3:20 pm: Flight controller poll: all go
3:23 pm: You will next hear from me either with a scrub announcement (one Heavy scrubbed at -0:03)
or an observer’s summary.
3:31 pm: Core engine cutoff, stage separation, Centaur ignition perfect.
At appx. T+ 1:10, I saw a contrail forming a bit left (more southerly azimuth) of expected visual acquisition. At ~+1:40, the contrail disappeared behind a cloud, and I saw nothing emerge above it. The sun is nearby in an otherwise clear sky, and I could see neither the vehicle nor the quite faint hydroxygen flame from the engines.
Here is a so-so pic of the rapidly-dissipating contrail from my phone cranked to 10x. At the time, the stack was probably near the upper right corner.
View attachment 5202788
That was the last Delta 4 Heavy from Vandenberg Space Force Base carrying the NROL-91 payload.