New SOXS instrument ready to observe fleeting cosmic events

ESO’s new facility, SOXS (Son Of X-Shooter), has successfully made its first observations at the La Silla Observatory in Chile. The spectrograph can be flexibly and rapidly scheduled to make observations of time-critical astronomical events, such as gamma-ray bursts, supernovae, and asteroids passing close to Earth.

From its new home on ESO’s 3.58-metre New Technology Telescope (NTT, pictured above), SOXS is a unique spectrograph that can be used to quickly observe transient cosmic events, at large distances or closer to home. Designed to see, simultaneously, in both optical and near-infrared wavelengths, SOXS is inspired by the X-shooter instrument currently operating on ESO’s Very Large Telescope.

“SOXS was conceived 10 years ago in view of what is now called time-domain astronomy,” says the project’s Principal Investigator Sergio Campana of the Brera Astronomical Observatory, Italy’s National Institute for Astrophysics (INAF). “After years of hard work, we are now positioned to play a major role in the study of astrophysical transients.”

Transients are astronomical phenomena that occur, or change in brightness or appearance, on relatively short timescales. This includes supernovae explosions, stars pulled apart by supermassive black holes, bursts of gamma-rays in the very distant Universe and fast-moving asteroids in our Solar System, all of which SOXS will study. Like X-shooter at the VLT, the instrument will have a wide variety of applications, but SOXS was specifically designed to conduct follow-up observations of transient events found in wide-field imaging or following real-time alerts sent to the astronomical community after specific cosmic events.

Since transient events last only a fleeting moment, which can be as short as a few milliseconds, it is critical that discoveries of these cosmic phenomena are followed up within minutes or hours by dedicated instruments. The nature of these objects will also change with time, sometimes dramatically so. To study and understand these changes, astronomers need uninterrupted follow-up over time with a dedicated instrument and telescope, something which is not commonly available given the demand for observing time on professional telescopes. SOXS on the NTT will fill this missing gap and provide unprecedented continuous coverage of these elusive, yet fascinating, astronomical objects.

“Specialising a medium-sized telescope like the NTT to a specific task like chasing transients is key to success,” says SOXS Project Manager Pietro Schipani of INAF Capodimonte Astronomical Observatory. “We are very proud of the people who have been working for many years to make our dream come true.”

SOXS simultaneously replaces NTT’s two previous spectrographs SOFI (Son of Isaac) and EFOSC2 (ESO Faint Object Spectrograph and Camera 2). “Effectively, it is two instruments in one”, says SOXS Instrument Scientist Paolo D’Avanzo of INAF-Brera, “with a double spectrograph designed to cover the whole optical and near-infrared wavelength range in a single shot, significantly increasing the efficiency of the NTT.” This device works similarly to how a prism splits light, allowing astronomers to unveil the characteristics of the events observed, such as the chemical composition or the distance to the source. Besides, it will also allow observations in imaging mode in the optical bands. The instrument is undergoing the final commissioning phase at the telescope under the supervision of the ESO team, ahead of starting the scientific observations of both the consortium and the wider ESO community.

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The SOXS consortium consists of:

• Italy: INAF (Osservatorio astronomico di Brera, Osservatorio astronomico di Capodimonte, Osservatorio astronomico di Padova, Osservatorio astronomico di Catania, Osservatorio astronomico di Roma and Fundación Galileo Galilei) — consortium leader
• Israel: The Weizmann Institute and Tel Aviv University
• UK: Queen’s University Belfast and University of Oxford
• Finland: University of Turku and Finnish Centre for Astronomy with ESO (FINCA)
• Chile: Millennium Institute of Astrophysics
• Denmark: The Niels Bohr Institute and Aarhus University

Courtesy of European Southern Observatory