Calar Alto Astronomical Observatory, jointly managed by the Junta de Andalucía, through the Consejería de Universidad, Investigación e Innovación, and by the Consejo Superior de Investigaciones Científicas (CSIC), has become an international reference for research and technology in the field of astronomy. A reference to this infrastructure, which has been in existence for more than 50 years, is therefore obligatory on World Astronomy Day, which is celebrated every 29 April.
The facilities of this centre are a world-class exponent, both for its state-of-the-art telescopes and instrumentation, and for the quality of the sky at its site in the Sierra de los Filabres, at an altitude of 2,168 metres, where 70% of the total time is useful for astrophysics. The infrastructure, which is the largest observatory in continental Europe, has become a unique centre for studies such as those of star formation in nearby galaxies or the search for exoplanets with conditions for the development of life.
Over the last decades, the complex has played a crucial role in the progress of Spanish astrophysics, serving as a base for numerous research projects, as well as for the training of its professionals. And this nuclear contribution to advances in this scientific field has been possible thanks to its constant process of technological renovation and innovation. The observatory is currently involved in several projects: the construction of the TARSIS integral field spectrograph, the modernisation of CARMENES and the development of the MARCOT project, a new concept of a giant, scalable and modular astronomical telescope.
MARCOT is still in the prototype phase, but it would increase the centre’s capabilities in the research of priority areas of astrophysics, such as the formation and evolution of planetary systems and galaxies or the deep knowledge of the solar system. This project is based on the combination of multiple small commercial telescopes, 40/50cm in size, whose operation as a unitary block can result in a giant-sized telescope, with a mirror aperture of up to fifteen metres, but at a much lower cost than with classical technology. Estimates suggest that a telescope designed according to this concept could cost up to ten times less than a classical large-aperture telescope. The design is modular and scalable, so it could be easily replicated in other locations.
This new model proposes to collect, via fibre optics, the information captured by each small telescope, combine it into a single fibre using a novel multi-mode photonic lantern not previously used in astronomical applications, capable of generating a single frame with a quality similar to that of a large-aperture telescope, but with better resolution and a larger field of view. It is, therefore, a very flexible technology that, connected to the CARMENES high-resolution spectrograph, would represent an extraordinary advance in the search for Earth-like exoplanets and in the characterisation of their atmospheric conditions in a wide sample of stars. Calar Alto already has a working prototype based on this system, consisting of seven small aperture (40 cm) telescopes, whose performance is expected to be equivalent to a single one-metre telescope.
The observatory is also developing the new TARSIS spectrograph for the study of distant galaxies, which, once built, will become part of the instrumentation available at the Calar Alto 3.5-metre telescope. Its characteristics will make it a unique instrument in the world, with a field of view several times larger than that of similar devices currently in service, and with the ability to observe in the entire visible spectrum, even down to the near ultraviolet. The estimated budget for the development of TARSIS is 7.9 million euros and it will be ready by 2027, placing this scientific infrastructure among the elite of modern astrophysics.
Alongside this initiative, the astronomical complex is also modernising the CARMENES spectrograph to improve its precision in the detection of Earth-like planets. Its commissioning meant a qualitative leap for Calar Alto, and since 2016 it has been successfully hunting exoplanets. Since then, it has made more than 20,000 observations and has made possible the discovery of 59 planets.
In order to carry out these actions, this facility will receive funds from the aid from the Complementary Plans developed by the Junta de Andalucía and the central government, with the support of European recovery funds, to promote R&D in astrophysics and high-energy physics. Specifically, part of this programme, which has an overall budget of 7.85 million euros, will be used, among other things, to finance the construction of the TARSIS spectrograph and improvements to CARMENES, as well as the commissioning of the CAVITY legacy in 2025.
129 publications in 2022
This complex has agreements for the use of its facilities with institutions such as the National Astronomical Observatory, the National Institute for Aerospace Technology, the Astrophysics Institute of Andalusia and the European Space Agency. It is also of key importance for the Andalusian academic world as a major laboratory for the development of cutting-edge instruments for Andalusian engineering schools, especially in the fields of optics, mechanics, electronics and software.
As a result of this collaboration, which supports many ongoing scientific investigations, about one hundred papers are published every year in high impact journals with data from Calar Alto in all branches of modern astrophysics. Last year, this production increased by almost 30% to 129 references, the highest number in the whole historical series compiled in the last two decades. In 2002, the volume of publications stood at 87, and since then they have been on an upward trajectory, reaching around a hundred in recent years. This evolution attests to the excellent health of the telescopes of this facility, their instrumentation and the staff working there.
A 50% stake
Since 2019, the regional government, through the Regional Ministry of University, Research and Innovation, has participated as manager and 50% co-owner of this top-level scientific complex, together with the CSIC, an involvement that has allowed the development of its lines of research to continue since then.
Since then, it has received 7.5 million euros in regional funds for its operation and operating costs. In addition to this, almost 500,000 euros have been raised by the observatory through the calls for R&D incentives opened by the Junta de Andalucía. With these resources, Calar Alto has acquired infrastructures for its modernisation, as well as for the adaptation of its computer system capacities.