SQ 1539 then AM 4175 at San Francisco
Boston → San Francisco → Atlanta
Timetable, San Francisco time
09:40SQ 1539 from Boston at the gate
08:00AM 4175 to Atlanta leaves the gatealso VS 5346, LA 7983
22 h 20 apart on the timetable, overnight
AM 4175 leaves 22 h 20 after SQ 1539 arrives on the timetable: more than half a day, so not a connection we count.