Edit: Launch was scrubbed in order to replace all 3 ground regulators. Launch NET 26th of September.
After many scrubbed attempts at launching, the former participant in the DARPA Rapid Launch Challenge, finally got their rocket off the launch pad, but it didn't clear the range.
Scott Manley with the summary: Astra Rocket 3.1 Destroyed After Losing Control
More details in an earlier post: New small sat launcher Astra launching for the first time
NASA ran a full-scale booster test for the Artemis mission to the moon by 2024 on SLS.
Smoke and Fire! NASA's Space Launch System Rocket Booster Test
Delta IV Heavy Launch
The first attempt was scrubbed due to weather.
The second attempt experienced a rare hot abort, 3 seconds before liftoff. Engines were already firing but were automatically shut down due to a ground systems failure.
Scott Manley with a recap of the abort and a guess at what the classified payload is: Classified Delta IV Rocket Launch Aborted With Seconds To Go
Delta IV Heavy NROL 44 Mission Profile
United Launch Alliance (ULA) is launching an unspecified satellite on a Delta IV Heavy for the [National Reconnaissance Office (NRO)](National Reconnaissance Office) from SLC-37B, Cape Canaveral, Florida to geostationary orbit (around 36'000 km).
There are hints that the classified payload might be an Orion Signals Intelligence Satellite. These satellites capture radio signals with their 100 m diameter antenna.
Scott Manley talking about the particularities of Delta boosters: Explaining the Delta Rocket Fireball
Check your local time of launch at: www.timeanddate.com
Useful links to stay up to date on launches:
Spaceflightnow.com: Launch Schedule
Everyday Astronaut: Prelaunch Previews
Space News:
NASA Spaceflight nasaspacefight.com
TMRO: YouTube
Be aware, this is rocket surgery.
Small disturbances can lead to postponed launches. Making sure everything is just right is way cheaper than risking big fireworks.