Three readers reported seeing an unusual light in the southern skies.
Taking off at about 19:21 local time (02:21 GMT), the first stage of the rocket returned safely to the air base about eight minutes later.
The spacecraft's landing near its concrete launching pad at the Vandenberg Air Force Base west of Los Angeles was the 30th landing of a rocket booster for the company and the 17th launch of the year, putting it on track for its stated ambition of 24 launches in 2018.
The light as viewed from Four Corners in the Briceland area.
Watching a rocket blast into space is always quite the sight, but it was particularly mesmerising for people living on California's coast on Sunday. At the time, the launch was scheduled to occur from the Kwajalein Atoll in the Pacific Ocean where SpaceX launched the now retired Falcon 1.
Saocom-1A is a 3,000-kilogram synthetic aperture radar (SAR) satellite for the Argentine space agency CONAE that was contracted in 2009 for a launch in 2012. The satellite is one of a planned six-satellite array.
The primary goal of the mission was to place the SAOCOM 1A satellite into orbit, but SpaceX also wanted to expand its recovery of first stages to its launch site at Vandenberg Air Force Base, about 130 miles northwest of Los Angeles.
As the biggest antenna in space for a civil mission, its main objective is to gather soil moisture information.
Argentina's satellite will reportedly track natural disasters, crop yields and soil-moisture levels from 385 miles (620km) above the earth.