Four ALMA antennas on the Chajnantor plain #1

8 March, 2017

Time-lapse of a whole night at the ALMA Array Operations Site (AOS), located at 5000 metres altitude on the Chajnantor plateau, in the II Region of Chile. As the Moon sets at the beginning of the night, three of the first ALMA antennas start tests as part of the ongoing Commissioning and Science Verification process. Because they are pointing at the same target in the sky at any moment, their movements are perfectly synchronised. As the sky appears to rotate clockwise around the south celestial pole (roughly on the upper left edge of the image), the Milky Way goes down slowly, until it is lying almost horizontal before sunrise. The centre of our galaxy becomes visible during the second half of the night as a yellowish bulge crossed by dark lanes in the centre of the image, just above the antennas. The flashes on the ground are the car lights of the guards patrolling at the AOS.
Credit: ALMA (ESO/NAOJ/NRAO). José Francisco Salgado