| Date |
Shutdown |
Fluence Actual [1e9] |
Fluence Saved [1e9] |
Event Notes |
| 2023-02-26
| manual
| 1.7
| 0.9
| See its corresponding
radiation memo and
storm page.
|
| 2023-03-20
| manual
| 3.3
| 1.4
| See its corresponding
radiation memo and
storm page.
|
| 2023-04-23
| manual
| 3.3
| 0.8
| See its corresponding
radiation memo and
storm page
|
| 2023-11-20
| manual
| 1.6
| 1.8
| See its corresponding radiation memo
|
| 2023-11-28
| no
| 1.6
| -
| M9.8 flare on the heels of a M3.4 flare, with an associated CME. On Dec 1, ACE rates were approximately stable at an elevated rate of >~30,000, with 1.5 days until RADMON disable. Extrapolated orbital fluence was ~4.7e9, with present fluence <~1e9. From ACIS-Ops discussion it was decided not to shut down. The storm passed several hours after, and ACE rates dropped precipitously, and the total orbital fluence was ~1.6e9. Not shutting down was the right call.
|
| 2023-12-16
| no
| ~1
| -
| X2.8 flare on Dec. 14th occurred following two earlier
flares in the same day of amplitude M2.3 and M5.8. The next day
there was an M6.8 flare. One major CME impacted later on the 15th,
raising ACE P3 rates to >~1e4. A second, much larger CME was
predicted to arrive in the next 24-48 hours, with a range of
predictions on the CME Scoreboard page ranging from midday (local)
on the 16th to the early morning of the 17th (local). A new science orbit
began the morning of the 16th, with a projected fluence of 2e9 at
the elevated ACE rates, absent a CME. It was agreed there was no
sense arguing for a shutdown before the CME impact was in the offing
and could be assessed. And in the end, the CME either never
arrived, or was only a very glancing blow that barely altered
declining ACE rates and only ~1e9 fluence was recorded and the large
CME predicted was not a major impact on Earth. The best guess is it
produced a minor impact on the morning of the 17th, ~10 hours later than the
ENLIL prediction, for which the projected impact was severe.
|
| 2024-01-22
| manual
| 1.7
| 2.6
| Flare during an otherwise calm week led to an
Earth-directed CME. This peaked just as ACIS exited the belts, with
P3 rates reaching nearly 2e5/s. The shutdown decision was fairly
straightforward; rates were slow with the entire orbit to go, with
no HRC time. Enlil plots showed a second crest of the CME was
possible. There was a stepped decay with a long plateau at
~25e3-50e3 which persisted for >12 hours, followed by a slow
decline, ~10x over the next 24 hours.. The recovery was slated
for ~24 hours after the manual shutdown, athough that load was
interrupted by an unrelated NSM. Shutting down was the right call.
|
| 2024-03-24
| autonomous (txings)
| 0.2
| 4.3
| An X1.1 flare occurred in the evening of Friday, March 22, during a week rifewith
small M-class flares. The CME was Earth-directed and arrived
about 1.5 days later, on Sunday March 24. Monitoring during the
radiation event was complicated by
recurrences of noisy/bogus (and high) data from the Korean ground
station for ACE. This resulted in spurious MTA alerts and also
contaminated the Replan Central orbital
fluence values and predictions.
On Sunday morning, ACE P3
rates rose rapidly over the course of several hours, peaking at
>350,000. The P5- and P7-scaled P3 rates were even higher, by
factors of a few. A radiation telecon was called and a manual shutdown
planned for the first available contact, near 2pm local time. During the SOH
checks at comm, we were relieved to see that txings had tripped, and
relatively early on while P3
rates were below 10,000. This saved ACIS from nearly all
of the storm's fluence.
|