Obsolete parameter now that the VLA is no longer using observe decks.
IATUTC sets the value of IAT-UTC. This is about 30 seconds now. This is only used if ``//PM'' cards are needed for the VLA since the zero-offset epoch must then be specified in IAT. SCHED does not use IAT for anything else. If not specified, the default is the value from the SLA library which should be ok, as long as that routine is maintained.