Weeellll ... comunicações subespaciais ... en.memory-alpha.org/wiki/Spacepace_communication
Depending on the actual distance between a vessel and the nearest subspace relay beacon, real-time communication was possible. An example of this is when Starfleet Lieutenant Reginald Barclay contacted the USS Enterprise-E, which was seven light years away from his location on the Jupiter Station, and spoke real-time to the ship's Counselor, Commander Deanna Troi.
Algumas notas no sensor de longo alcance en.memory-alpha.org/wiki/Long_range_sensor_scan
In 2267, the sensors of the USS Enterprise were able to scan out to one parsec (3.26 light years) and give a near instantaneous result. (TOS: "The Enterprise Incident")
In 2367. Lieutenant Commander Geordi La Forge stated that the long range sensors aboard the USS Enterprise-D were able to scan a radius of ten light years within a 24-hour period; effectively, one sector per day. (TNG: "The Wounded")