F9 4702 then DL 518 at Atlanta
Austin → Atlanta → Boston
Timetable, Atlanta time
19:10F9 4702 from Austin at the gate
16:25DL 518 to Boston leaves the gate
21 h 15 apart on the timetable, overnight
DL 518 leaves 21 h 15 after F9 4702 arrives on the timetable: more than half a day, so not a connection we count.