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February 3, 2023



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Points of views: DANIEL ALTSCHULER


Large diameters are very important in astronomy. History tells us that, when we increase the size we can achieve, (....) we make discoveries which, quite simply, were out of reach for the instruments we were using.
Daniel Altschuler

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    We are naturally very interested in the astronomy and astrophysics community’s opinion of the Gran Telescopio CANARIAS (GTC). Here we talk to Daniel Altschuler, Director of the Arecibo Observatory in Puerto Rico.

    Much of the energy is emitted by objects in space reaches us in the form of radio waves: studying them is called radio astronomy, and the instruments used to do it are called radio telescopes.

    The largest radio telescope in the world is in Arecibo (Puerto Rico), and it is a spherical reflector 305 metres in diameter and 51 metres deep. The surface is made up of some 40,000 perforated aluminium panels (each one approximately 1mx2m). It is the huge size of the reflector that makes it so important for scientists - it is the largest curved antenna on the planet, making it the most sensitive radio telescope in the world.

    NAIC (The National Astronomy and Ionosphere Centre), is housed at the Arecibo Observatory and is run by the University of Cornell with the assistance of the NSF (National Science Foundation).

    Professor Daniel Altschuler, Professor at the University of Puerto Rico and Director of the observatory, is responsible for running and administering this centre of astronomical research, planetary studies and atmospheric sciences. He recently published a book, “Children of the Stars”.


    How important to astronomy are large diameter telescopes like the Arecibo radio telescope and the GTC?

    Large diameters are very important to astronomy. History tells us that, when we increase the size we can achieve - the capacity of our instruments - we make discoveries which, quite simply, were out of reach for the instruments we were using. The hope is that any instrument which significantly increases some of our observing capacities will expand the parameters we can work with, allowing us to discover new phenomena or deepen our understanding of those we are already aware of.

    For the next generation, giant telescopes many metres across are already being discussed - such as the ‘Overwhelmingly Large Telescope’, in Chile. Similarly, in radio astronomy, the talk is of a 1km square array of radio telescopes – ‘The Square Kilometer Array’. It will be very difficult to build, and funding will be a challenge, but it will be the next step for radio astronomy. The optimists believe we will see it in the next 10 or 15 years; the pessimists will not put a date on it.

    How will a large telescope like the GTC, operating in the optical and infrared ranges, and a large radio telescope like Arecibo, complement one another?

    One example of how the two telescopes can work together is the study of low luminosity galaxies. Although they are hard to find because they do not give off much light, we are nonetheless interested in finding out whether these galaxies have gone through any star-forming processes. This type of work demands a highly sensitive telescope.

    Another use for the Gran Telescopio CANARIAS will be continuing the discoveries made at Arecibo over the last few years, when we began to ‘comb the sky’ with the aim of finding galaxies in formation. These are galaxies in which no stars have been formed, making them ideal objects for tracking with an optical telescope.

    Sara Gil
    Natalia R. Zelman

    To find out more about Daniel Altschuler and his research click here.

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