Chilean observatory benefits from clear skies

Nocturnal image of the Cerro La Silla European Southern Observatory (ESO) very large telescope site located at Paranal, Chile, was taken about 90 minutes after sunset on December 7, 1996, from the "NTT Peak," a mountain to¥inland from Paranal, looking southwest. The picture is a fixed six-minute exposure, which is why the stars are seen as small trails. At the exposure time the sun was more than 20° under the western horizon, but some scattered light in the Earth`s atmosphere is still se

Chilean observatory benefits from clear skies

Nocturnal image of the Cerro La Silla European Southern Observatory (ESO) very large telescope site located at Paranal, Chile, was taken about 90 minutes after sunset on December 7, 1996, from the "NTT Peak," a mountain to¥inland from Paranal, looking southwest. The picture is a fixed six-minute exposure, which is why the stars are seen as small trails. At the exposure time the sun was more than 20° under the western horizon, but some scattered light in the Earth`s atmosphere is still seen along the horizon.

The field of the photo covers nearly 90°. The south celestial pole is located to the upper left, and the celestial equator is just outside the right border. The zodiacal light caused by the reflection of sunlight in small dust particles in the main plane of the solar system is visible as a cone of light rising from the horizon along the ecliptic, to the right in the picture.

The brightest object to the right is the trail of Jupiter (magnitude 1.4). The stars below are located in the southern constellation of Sagittarius. The trail of medium brightness right of the center is that of Mercury (magnitude 0.2). The two relatively bright stars, just above the Paranal observatory, are Beta and Gamma of the constellation Ara (the altar). The band of the Milky Way stretches along the horizon but is barely visible here.

This year will be a decisive one for the ESO-VLT project. Only one year remains before first light is announced from the first of the four giant 8.2-m-diameter mirrors that will installed on the telescope in the VLT array located in Paranal, where the sky is clear during almost 300 nights per year.

Many related events will be held on the Paranal site during the coming months before the start of astronomical tests. These include erection of mechanical structures with all the electrical parts, testing of the control software, and installation of the optical system, in particular the prime 8.2-m mirror.

Roland Roux

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