DL 1007 then F9 2552 at Atlanta
Washington National → Atlanta → Philadelphia
Timetable, Atlanta time
21:41DL 1007 from Washington National at the gate
16:11F9 2552 to Philadelphia leaves the gate
18 h 30 apart on the timetable, overnight
F9 2552 leaves 18 h 30 after DL 1007 arrives on the timetable: more than half a day, so not a connection we count.