Development and construction of TARSIS, an unprecedented astronomical instrument

TARSIS is the next-generation instrument for the Calar Alto 3.5-metre telescope in Spain and will be unique in its ability to detect near-ultraviolet light and its unprecedented field of view. TARSIS will be a great challenge because it will obtain information in such a wide energy range and in a field of two-dimensional spectroscopy that is unprecedented in any telescope on the ground or in space.

The name TARSIS, an acronym for the English Tetra-ARmed Super-Ifu Spectrograph, alludes to its optical design based on four arms, three of them sensitive to blue wavelengths and one sensitive to red wavelengths. The combination of a wide field of view (3×3 square arc minutes) and high sensitivity from ultraviolet (in the range known as UV-A rays) to red wavelengths will make TARSIS a unique instrument. The design of TARSIS and the transparency of Calar Alto’s sky will allow observation in the full UV-A range, a domain almost unexplored from Earth.

“Only the unique features of TARSIS allow us to fully map galaxy clusters at distances where we can still resolve the internal structure of galaxies over a wide range of energies,” says Jorge Iglesias, TARSIS Co-Principal Investigator at the Institute of Astrophysics of Andalusia, Spain. Armando Gil de Paz, co-principal investigator of the project at the Complutense University of Madrid (UCM) in Spain, adds that “TARSIS is a great challenge, since obtaining information in such a wide energy range and in a field of this size in two-dimensional spectroscopy It is unprecedented in any telescope on Earth or in space. So, while classical spectroscopy barely covered a narrow slice of the sky, TARSIS is going to observe 160 of them.”

Once the development is complete, TARSIS will become part of the instrumentation available in the 3.5-meter telescope at the Calar Alto observatory in Almería. However, during the first years of observations, TARSIS will be devoted mainly to the CATARSIS project, which will study a sample of sixteen distant galaxy clusters and will allow a glimpse of earlier stages of the universe: these are galaxies between 20% and 25% less massive than the current ones, but which, on their way to becoming the galaxies we see today, formed stars at a rate three times higher than the present. “This is the first time that we will systematically study the largest and most massive structures in the universe, measuring the speeds of each and every one of the galaxies that make them up, from their center to the outermost regions,” says Patricia Sánchez Blázquez , head of science at CATARSIS and member of the UCM Instrumental and Extragalactic Astrophysics Group and the UCM instrument team.

TARSIS is the next-generation instrument for the Calar Alto 3.5-meter telescope in Spain and will be unique in its ability to detect near-ultraviolet light and its unprecedented field of view. (Image: © Armando Gil de Paz / UCM)

The CATARSIS observations will make it possible to validate the standard cosmological model and understand the nature of dark matter and dark energy, as well as the relationship between the evolution of galaxies and their environment.

This project is co-led by the Complutense University of Madrid and the Institute of Astrophysics of Andalusia, in close collaboration with the Calar Alto Observatory (Hispanic Astronomical Center in Andalusia, CAHA), three Andalusian universities (Almería, Granada and Seville), the Center of Astrobiology (CAB), the industrial partner FRACTAL SLNE and the Mexican INAOE. (Source: UCM)