Son Of X-Shooter

SOXS (Son Of X-Shooter) is a new instrument to be installed on the 3.5-m New Technology Telescope (NTT) at ESO’s La Silla Observatory in Chile. This instrument will be a unique spectroscopic facility for following up transient and variable astronomical events from ongoing and future imaging surveys. It will provide a key spectroscopic partner to any kind of transient survey, becoming the premier transient follow-up instrument in the southern hemisphere.

Transients are astronomical events that only last for a certain amount of time. They are currently being discovered at a rapid rate which will only be increased with powerful future survey telescopes, and so the scope to further our understanding within this field is immense. However, it is critical that these discoveries are rapidly followed up within minutes or hours by dedicated optical telescopes. Designed to see in optical and near-infrared wavelengths, SOXS will be able to achieve this.

In the last few years, optical surveys have discovered new classes of supernovae — super-luminous supernovae — and rare transients,” comments Sergio Campana from INAF (at Osservatorio astronomico di Brera) in Italy, the institution leading the SOXS consortium. “SOXS will help us deepen our knowledge of these sources. We will study in detail the disruption of stars by supermassive black holes, and we can also try to pinpoint the counterparts of gravitational wave sources or very high-redshift gamma-ray burst counterparts, when the Universe was only several hundreds of millions years old.”

ESO has strategically chosen the SOXS spectrometer to be be installed on the NTT at the La Silla Observatory, on the edge of Chile’s Atacama Desert. Here, SOXS will follow-up on a mixture of transients encompassing all distance scales and branches of astronomies, including fast alerts (such as gamma-ray bursts and gravitational waves), mid-term alerts (such as supernovae and X-ray transients), and fixed-time events (such as the close-by passage of a minor planet or asteroid). It will also have the scope to observe exoplanet transits, active galactic nuclei and blazars, tidal disruption events, fast radio bursts, and more.

SOXS aims to observe and classify these sources, to discover new kinds of sources, and to study and characterise the most interesting ones.

But how does SOXS work?

The instrument separates the incoming white light into a spectrum, where the position on the detector corresponds to a given wavelength, like the rainbow,” explains Sergio Campana. “The presence of emission and absorption lines — which show up as bright or dark lines in the spectrum — is a clear marker of specific elements, which allows us to study the chemical composition and the redshift of the source. For cosmological sources — that is, sources outside our galaxy — this allows us to determine how far away they are.

The schedule of SOXS will be flexible and updated daily in order to respond to fast alerts, with observers on site ready to respond instantaneously.

SOXS is expected to see first light in 2020.


This table lists the global capabilities of the instrument. The authoritative technical specifications as offered for astronomical observations are available from the Science Operations page.

Location: La Silla Observatory
Telescope: New Technology Telescope
Focus: Nasmyth
Type: Spectrograph
Wavelength range: 350–1750 nm
Spatial resolution: Seeing limited
Spectral resolution: R~4500
First light: 2020 (planned)
Science goal: Following up, studying, and classifying transient sources from ongoing and future imaging surveys
Images taken with the instrument: Link
Images of the instrument: Link
Videos of the instrument: Link
Press Releases with the instrument: Link