time need to be hard code

dear export,

I need to write a PL/SQL for sysdate need to be hard code and generate a report.

table name:

creat table roam(mobileno varchar(20), event_date date, chrges integer(12,3)

97777777 7 |12-08-2011 03:45:23 | 50.00
975555527 |12-08-2011 02:45:23 | 50.00
977773337 |12-08-2011 01:40:23 | 50.00
976766767 |12-08-2011 00:46:23 | 50.00
977565657 |12-08-2011 03:45:23 | 50.00
977777777 |12-08-2011 03:45:23 | 50.00
977777777 |12-08-2011 03:45:23 | 50.00

I need to get this records ever day 24hr before 03:00:00 time
y-day 03:00:00<event_date >today 03:00:00

this 03:00:00 need to hard code and date must be changed.

pl help me

thanks

ashwan