SOXS: a wide band spectrograph to follow up transients

Abstract

SOXS (Son Of X-Shooter) will be a spectrograph for the ESO NTT telescope capable to cover the optical and NIR bands, based on the heritage of the X-Shooter at the ESO-VLT. SOXS will be built and run by an international consortium, carrying out rapid and longer term Target of Opportunity requests on a variety of astronomical objects. SOXS will observe all kind of transient and variable sources from different surveys. These will be a mixture of fast alerts (e.g. gamma-ray bursts, gravitational waves, neutrino events), mid-term alerts (e.g. supernovae, X-ray transients), fixed time events (e.g. close-by passage of minor bodies). While the focus is on transients and variables, still there is a wide range of other astrophysical targets and science topics that will benefit from SOXS. The design foresees a spectrograph with a Resolution-Slit product ≈ 4500, capable of simultaneously observing over the entire band the complete spectral range from the U-to the H-band. The limiting magnitude of R~20 (1 hr at S/N~10) is suited to study transients identified from on-going imaging surveys. Light imaging capabilities in the optical band (grizy) are also envisaged to allow for multi-band photometry of the faintest transients. This paper outlines the status of the project, now in Final Design Phase.

The Zwicky Transient Facility Bright Transient Survey. II. A Public Statistical Sample for Exploring Supernova Demographics*

“…The commissioning of more such facilities, alongside new high-throughput multichannel spectrographs on existing telescopes, would enable highly complete spectroscopic coverage of the transient sky to be extended to greater depths and larger sky areas. Several projects of this type are in development, including a proposed SED Machine clone at Kitt Peak, the New Robotic Telescope on La Palma (Gutiérrez et al 2019), the Next Generation Palomar Spectrograph (Jiang et al 2018), and the Son of X-shooter at La Silla (Schipani et al 2018). A concerted, organized effort by these facilities could easily increase the size of highly complete samples similar to BTS by an order of magnitude or more by the middle of the decade.…”

Son of X–Shooter: a multi–band instrument for a multi–band universe

“…SOXS [40] will simultaneously cover the electromagnetic spectrum from 0.35 to 2.0 µm using two arms (UV-VIS and NIR) with a product slit-resolution of ∼ 4500. The throughput should enable to reach a S/N∼ 10 in a 1-hour exposure of an R=20 mag point source.…”

Optical design of the SOXS spectrograph for ESO NTT

“…For ADC angle 0˚, prisms are aligned for maximum dispersion. A model of the form prism_angle = acos( ( 3.6e-1 -1.2e-3 x T + 4.4e-4 x P ) x tan( zenith_angle ) ) (1) has been fitted (plotted as solid lines) in Figure 2 and will be implemented in the software. The atmospheric dispersion in the NIR wavelength range is expected to be less than 0.5 arcsec and it was regarded as acceptable, therefore no ADC is included in this arm.…”