The IRAM 30-meter telescope is a radio telescope used for astronomical observations in the millimeter range of wavelengths, operated by the Institute for Radio Astronomy in the Millimeter Range (IRAM) and located in the Sierra Nevada, Spain, close to the Pico Veleta peak. The 30-meter telescope is the most sensitive singular radio telescope in the world. Its large surface and wide-angle camera make it a perfect tool for the exploration of large cosmic objects such as interstellar clouds, birthplaces for stars, and even galaxies. The 30-meter telescope also allows astronomers to access parts of the southern skies and therefore to observe the black hole at the center of our galaxy.
Each year more than 200 scientists from all over the world visit this observatory to explore the universe at millimeter wavelengths, with interests going from the Solar System to interstellar dust and gas or cosmology. Together with IRAM's second facility, the NOEMA observatory, the 30-meter telescope is part of the global Event Horizon Telescope array. It was the only station in Europe to participate in the 2017 EHT observing campaign that produced the first-ever image of a black hole.
Built in four years (1980-1984), the telescope operates at 2850 meters above sea level. Due to its large surface, the 30-meter telescope is highly sensitive and well adapted to detect weak sources. The surface of the parabola with its 420 panels is adjusted to a precision of 55 micrometers, corresponding to the width of a human hair.
The telescope is equipped with a suite of heterodyne receivers and continuum cameras operating at wavelengths of around 0.8, 1, 2, and 3 millimeters. By pointing the telescope towards a celestial source, and then by scanning and tracking the source, astronomers can build up radio images - of complete galaxies or regions of star formation in the Milky Way. With its ability to observe simultaneously at several wavelengths, the telescope can produce multiple images of the same region at once.
IRAM offers guided tours through the observatory and public talks during the summer months.
Compared to optical astronomy, which is sensitive to the hot universe (stars are generally a few thousand degrees Celsius), radio telescopes that operate in the millimeter wavebands, such as the IRAM 30-meter telescope, can view the cold universe (around -250 degrees Celsius). Both IRAM facilities are able to see the formation of the first galaxies in the universe, to observe super-giant black holes at the center of galaxies, to analyze the chemical evolution and dynamics of nearby galaxies, to detect organic molecules and possible key elements of life, and to investigate the formation of stars and the appearance of planetary systems.As part of the EHT array, the IRAM 30-meter telescope obtained the first-ever image of a black hole. But EHT is not the only area in which IRAM has done pioneering work. For instance, the first high-resolution radio observations of the heart of the Milky Way galaxy and its black hole, named Sagittarius A*, were made in 1995 – with a combination of the IRAM 30-meter telescope and the NOEMA array (former Plateau de Bure Interferometer). The telescope also obtained the first complete and detailed radio images of nearby galaxies and their gas. Together with NOEMA it discovered one third of the interstellar molecules known to date (published ApJ, 2018, Brett A. McGuire).