I have to run this in a script thro' cron everyday to capture information from 6.00 AM to previous day 6.00 AM.(9i/10g)

Anyone having any idea what is the right way of using date or timestamp here(where clause)?

Select
USERNAME DBA_ID
,TERMINAL
,to_char(timestamp,'mm/dd/yy hh24:mi:ss') TIMESTAMP
,OBJ_NAME
,ACTION_NAME
from
sys.dba_audit_trail
where
to_date(to_char(timestamp,'HH24:MI:SS'),'HH24:MI:SS') between to_date('06:00:00','HH24:MI:SS') and to_date('06:00:00','HH24:MI:SS')-1;