USA 352 cataloged from NROL-123. Which leaves USA 350 and USA 351 unused. I presume these are reserved for the Starshields aboard this launch (which are not cataloged yet):
Space-Track has now cataloged the NROL-123 Electron launch. There are actually FOUR payloads: "USA 352", MOLA, Aerocube 16A and Aerocube 16B. (Likely the earlier statement of 3 implies that AC-16A/B were deployed attached to each other and then separated?).
USA 352 is presumably an NRO payload. AC-16A/B are cubesats from the Aerospace Corporation. It is known that the Naval Postgrad School was developing a cubesat called Mola, so that's probably the other one.
https://twitter.com/planet4589/status/1771270082758426710
Edit to add:
The identification of the Electron payload 2024-053A as "USA 352" changes the balance of evidence on the Mar 19 Starlink Group 7-16 launch: it now seems likely that it DID carry two classified payloads, likely Starshield, to be designated USA 350 and USA 351 (59274/59275?)
https://twitter.com/planet4589/status/1771276762615333178
This is a ground-based video, end-to-end, taken from San Diego (200 miles south of Vandenberg Space Force Base) and located about halfway through the second stage burn. From this vantage point, you can see from MECO, the booster and fairings following behind the second stage within the plume. Then, eventually, the booster continues on its ballistic trajectory right up to the entry burn. Although the video continues to the second engine cutoff (SECO), the landing burn is not visible as it is below the horizon.
In the second video, I edited a three-way with the SpaceX broadcast with two other videos. One video was taken from Santa Barbara and captured the Falcon 9 through the main engine cutoff (MECO) and a little beyond, and then we followed with the San Diego video. Enjoy!
With this first video advance to 1:05 to start viewing the F9. The second video starts viewing from the beginning.
Some reusability stats for this launch (Starlink Group 7-16):
Booster B1075.10 turnaround time:
49 days 20 hours 31 minutes(its previous mission was Starlink Group 7-12 on Jan 29, 2024 UTC).
FYI: median turnaround time for Falcon 9 / Heavy boosters is currently 52.08 days *
* – based on the last 30 launches, excluding new first stages.
Launchpad SLC-4E turnaround time:
7 days 22 hours 19 minutes(the previous launch from this pad was Starlink Group 7-17 on Mar 4, 2024 UTC).
FYI: median turnaround time for SLC-4E is currently 10.97 days *
* – based on the last 30 launches.
The same type of stats for previous SpaceX launches may be found on
this spreadsheet online.