Timestamp in an External Table

Since this wasn't particularly easy to find, and it took several tries, I decided to post it here. As most things, once you know how to write it, it's not particularly tricky.

Input Data from External Table:
1,Jan 8 1998 12:43:27:012AM
2,Feb 19 1998 2:43:27:111PM
3,Jan 8 2008 3:49:27:693PM

Create Table Ext_Dt
(  Item       Number
 , Needed_By  Timestamp
)
Organization External
(
 Type Oracle_Loader
 Default Directory Ext
 Access Parameters
 (
    Records Delimited By Newline
    Badfile 'Date.Bad'
    Logfile 'Date.Log'
    Fields Terminated By ','
    Missing Field Values Are Null
       (
          Item,
          Needed_By Char Date_Format Timestamp Mask 'Mon Dd Yyyy Hh:Mi:Ss:Ff3am'
       )
 )
Location (Ext:'Dt.Txt')
)
Reject Limit Unlimited;

Select Item
     , Needed_By
     , To_Char(Needed_By,'Mon' ) Mth
     , To_Char(Needed_By,'Hh24') Hr
  From Ext_Dt;