Citizen AT9010-52E Instruction Manual page 37

Setting Summer Time (SMT)
To automatically enable
Summer Time (SMT)
when using the watch
in an area where the
time signal can be
received:
To enable Summer
Time (SMT) manually
when the time signal
can not be received:
36
STD-AU SMT-AU
SMT-AU
Set the summer time setting to
automatic (the summer time
setting (SMT / STD) is updated
automatically upon receiving
the radio signal)
Set the summer time SMT
when you want to do so.