Thanks everyone. My motive for asking was due to an unexpected Rapid ShutDown just after 5pm CDT December 9.
By coincidence, I just became aware of "Sunspot AR3511" which erupted on Dec. 8th (2307 UT), producing an M5-class solar flare and a
shortwave radio blackout. A bit of a stretch, I know, but the coincidence is intriguing.