Optics

YEPUN sees the light

Nov. 1, 2000

After nearly 15 years of hard work, the European Southern Observatory (ESO) Very Large Telescope (VLT) in Cerro Paranal, Chile, is finally operational. The fourth and final 8.2-m (315-in.) unit telescope, YEPUN (right, front) successfully achieved first light in September. By 2003, the ESO plans to combine the four large independent telescopes with three dedicated 1.8-m auxiliary telescopes that will move on rails to form the VLT Interferometer to achieve unprecedented milli-arc-sec (0.001-in.) angular resolution for wavelengths from 300 nm to 25 µm.

YEPUN, named for Venus in the Mapuchen language of Chile, obtained an exposure of the planetary nebula Hen 2-428 (top), a stellar gas cloud approximately 7000 light years away, appearing between the constellations Sagitta and Aquila. Planetary nebulae are caused when a dying star (the bluish object at the center) ejects its outer layers. The image is a color composite of three exposures using red, green, and blue optical filters. The image quality here is 0.9 in., which met expectations considering windy and moonlit conditions.

The image served to evaluate provisionally the performance of the new telescope in terms of mechanical and optical quality. The ESO staff pronounced YEPUN fit for the subsequent commissioning phase.

About the Author

Valerie Coffey-Rosich | Contributing Editor

Valerie Coffey-Rosich is a freelance science and technology writer and editor and a contributing editor for Laser Focus World; she previously served as an Associate Technical Editor (2000-2003) and a Senior Technical Editor (2007-2008) for Laser Focus World.

Valerie holds a BS in physics from the University of Nevada, Reno, and an MA in astronomy from Boston University. She specializes in editing and writing about optics, photonics, astronomy, and physics in academic, reference, and business-to-business publications. In addition to Laser Focus World, her work has appeared online and in print for clients such as the American Institute of Physics, American Heritage Dictionary, BioPhotonics, Encyclopedia Britannica, EuroPhotonics, the Optical Society of America, Photonics Focus, Photonics Spectra, Sky & Telescope, and many others. She is based in Palm Springs, California.