Ryan, Richard, Dave:
The GC UPS reported time on battery this morning between 06:53:56 - 06:54:01 PST.
Attached fast mains mon channels show a slight dip in voltage for all three phases as seen in the corner station, lasting for only about 5 cycles. H1 and CDS rode through this with no issues, H1 stayed locked.
Ryan walked the MSR and GC server rooms, nothing untoward was found.