Nota de Imprensa

Getting ISAAC Ready for the VLT

5 de Março de 1998

We continue the publication of video clips which illustrate the rapid progress of the VLT project. The present footage of the ISAAC (Infrared Spectrometer and Array Camera) instrument for the ESO Very Large Telescope was obtained last week by the ESO EPR Video Team at the ESO Headquarters in Garching.

This video clip shows the Infrared Spectrometer and Array Camera (ISAAC) for the VLT during its final integration and testing in Europe, prior to installation at the first VLT 8.2-m Unit Telescope (UT1) towards the end of this year.

Like its smaller colleague SOFI at the ESO New Technology Telescope (NTT), cf. eso9803, ISAAC has been built by the Instrumentation Division of ESO. It is a versatile instrument designed to produce both infrared images and spectra of a wide variety of astronomical objects at wavelengths between 1 and 5 microns.

The infrared region of the spectrum is playing an increasingly important role in astronomy and astrophysics and ISAAC will allow Europe's astronomers to make important new observations in this spectral region. The objects to be studied include solar system bodies, star forming regions in the Milky Way and the active nuclei of nearby galaxies.

In particular, however, its combination of a relatively large field of view and high sensitivity is expected to revolutionize searches for intrinsically faint objects such as cool, low mass, stars and extremely distant galaxies (whose visible light has been shifted into the infrared by doppler shift caused by the expansion of the universe). A prime goal is to detect and study the earliest, primeval, galaxies in which the first stars were born.

By comparison with previous infrared instruments, ISAAC is larger and heavier with an opto-mechanical assembly weighing 350 kilograms. Compared with instruments in the visible, the complication is that both this and the two large format array detectors at its heart have to be cooled to cryogenic temperatures below -200 o C. This is achieved by enclosing the instrument in a 1.5-m diameter vacuum vessel and cooling it with two mechanical cooling engines which are assisted by a continuous flow of liquid nitrogen during the initial cool-down phase.

Integration, alignment and testing of ISAAC consequently become major and quite time consuming activities – as can be seen in the video clip.

For more details about this new VLT instrument, please refer to the ISAAC WWW page.

These video sequences were obtained in late February 1998.

More information is available at the ESO website about the VLT project. Note also that preparations are now being made for the UT1 First Light Event that will occur within a few months.

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