I photographed the ALMA Array Operations Site (5000 meter altitude) illuminated by the Moon waxing towards half phase with a 360-degree camera. It is Jupiter that shines brightly above the small mountain on the north side. The constellation can be seen Orion setting above the Japan-made 7-meter antenna group which is illuminated by the green lights. Also, the Southern Cross and the Milky Way are captured in the direction of south where you can see many North American and European 12-meter antennas.

A Different World Illuminated by Green

When you see night view photos of ALMA Array Operations Site, you might find the antennas illuminated in green. This is because of the safety check lights attached to the antennas. Although the ALMA antennas have very huge structures, with 7 meter or 12 meter diameters, they can be driven at a high speed. Moreover, the antennas are driven remotely from the ALMA Operations Support Facility (2900 meter altitude) which is 30 kilometers away. Since inadvertently approaching the antennas can lead to unpredictable accidents, we inform the staff members that they can approach the antennas when these green lights are on. When the antennas are not working, the green lights are turned on. In high-altitude areas with low oxygen, our judgment may be impaired. Therefore, various safety measures are taken to prevent accidents.

Text by: Masaaki Hiramatsu (NAOJ Chile Observatory)
Translation by: Hiroko Tsuzuki and Ramsey Lundock (Public Relations Center, NAOJ)

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• ALMA