According to “Spaceweather”:
“On Jan. 8th, asteroid 2019 AS5 flew past Earth only 8600 km above our planet’s surface. Nine hours after the flyby, it was discovered by the the Mt. Lemmon Survey telescope in Arizona. The asteroid was closer to our planet than many satellites.”
Note the word “after”! Useful that!
To be fair it goes on to say:
“If the 1 to 2 meter-wide space rock had hit Earth (and it almost did) it would have caused a brilliant fireball in the atmosphere with sonic booms and scattered meteorites on the ground–but no serious damage.”