If it is truly UTC, then Ken's formula should do it (it was 1972 when the switch from GMT to UTC happened though) - you would be better off to do the conversion to a date in your database, as you can be assured that an Oracle back end is going to be several orders of magnitude faster than doing the conversion through SCR on the client.
About every second or third year has a leap second though, so unless you establish a table for leap seconds you will have a cumulative error of a few seconds.
There is an Oracle forum on Tek-Tips that would be able to give you some tips on the best conversion.
Malcolm
wynden@telus.net