In this paper, we describe the wide-field spectroscopic survey telescope (WST) project. WST is a 12-metre wide-field spectroscopic survey telescope with simultaneous operation of a large field-of-view (3 sq. degree), high-multiplex (20,000) multi-object spectrograph (MOS), with both a low and high-resolution modes, and a giant 3×3 arcmin2 integral field spectrograph (IFS). In scientific capability, these specifications place WST far ahead of existing and planned facilities. In only 5 years of operation, the MOS would target 250 million galaxies and 25 million stars at low spectral resolution, plus 2 million stars at high resolution. Without need for pre-imaged targets, the IFS would deliver 4 billion spectra offering many serendipitous discoveries. Given the current investment in deep imaging surveys and noting the diagnostic power of spectroscopy, WST will fill a crucial gap in astronomical capability and work in synergy with future ground and space-based facilities. We show how it can address outstanding scientific questions in the areas of cosmology; galaxy assembly, evolution, and enrichment, including our own Milky Way; the origin of stars and planets; and time domain and multi-messenger astrophysics. WST’s uniquely rich dataset may yield unforeseen discoveries in many of these areas. The telescope and instruments are designed as an integrated system and will mostly use existing technology, with the aim to minimise the carbon footprint and environmental impact. We will propose WST as the next European Southern Observatory (ESO) project after completion of the 39-metre ELT.
We present a comprehensive overview of the collaborative efforts between the End-to-End (E2E) Simulator and the Data Reduction Software (DRS) team, focusing on the modeling of the U-band efficient Cassegrain spectrograph CUBES (ESO-VLT). The E2E model is a Python-based numerical simulator capable of rendering synthetic raw frames with high precision for both astronomical and calibration sources, starting from their 1-d radiation spectra up to the data produced by the detectors. Data from the E2E are processed by the prototype Data Reduction Software (pDRS), a Python library which implements the critical algorithms of the DRS. The PDRS performs wavelength calibration and extracts a 1-d spectrum from one or more reduced science exposures. The 1-d spectrum produced by the extraction routine is meant to be compared directly with the input spectrum fed to the E2E, actually “closing the loop” allowing for a real end-to-end assessment of the instrument capabilities.
We present our numerical simulation approach for the End-to-End (E2E) model applied to various astronomical spectrographs, such as SOXS (ESO-NTT), CUBES (ESO-VLT), and ANDES (ESO-ELT), covering multiple wavelength regions. The E2E model aim at simulating the expected astronomical observations starting from the radiation of the scientific sources (or calibration sources) up to the raw-frame data produced by the detectors. The comprehensive description includes E2E architecture, computational models, and tools for rendering the simulated frames. Collaboration with Data Reduction Software (DRS) teams is discussed, along with efforts to meet instrument requirements. The contribution to the cross-correlation algorithm for the Active Flexure Compensation (AFC) system of CUBES is detailed.
In the era of Extremely Large Telescopes, the current generation of 8-10m facilities are likely to remain competitive at ground-UV wavelengths for the foreseeable future. The Cassegrain U-Band Efficient Spectrograph (CUBES) has been designed to provide high instrumental efficiency ( > 37%) observations in the near UV (305-400 nm requirement, 300-420 nm goal) at a spectral resolving power of R > 20, 000 (with a lower-resolution, sky-limited mode of R ∼ 7, 000). With the design focusing on maximizing the instrument throughput (ensuring a Signal to Noise Ratio – SNR– ∼ 20 per spectral resolution element at 313 nm for U ∼ 17.5 mag objects in 1h of observations), it will offer new possibilities in many fields of astrophysics: i) access to key lines of stellar spectra (e.g. lighter elements, in particular Beryllium), extragalactic studies (e.g. circumgalactic medium of distant galaxies, cosmic UV background) and follow-up of explosive transients. We present the CUBES instrument design, currently in Phase-C and approaching the final design review, summarizing the hardware architecture and interfaces between the different subsystems as well as the relevant technical requirements. We describe the optical, mechanical, electrical design of the different subsystems (from the telescope adapter and support structure, through the main opto-mechanical path, including calibration unit, detector devices and cryostat control, main control electronics), detailing peculiar instrument functions like the Active Flexure Compensation (AFC). Furthermore, we outline the AIT/V concept and the main instrument operations giving an overview of its software ecosystem. Installation at the VLT is planned for 2028/2029 and first science operations in late 2029.
KEYWORDS: Signal to noise ratio, Sensors, Device simulation, Calibration, Telescopes, Spectrographs, Software development, Ecosystems, Standards development, Control systems
CUBES (Cassegrain U-Band Efficient Spectrograph) is the recently approved high-efficiency VLT spectrograph aimed to observe the sky in the UV ground-based region (305-400 nm) with a high-resolution mode (∼ 20K) and a low-resolution mode (∼ 5K). In this paper we will briefly describe the requirements and the design of the several software packages involved in the project, namely the instrument control software, the exposure time calculator, the end-to-end simulator, and the data reduction software suite. We will discuss how the above mentioned blocks cooperate to build up a “software ecosystem” for the CUBES instrument, and to support the users from the proposal preparation to the science-grade data products.
Following the idea originally proposed during the ESO-Workshop The Very Large Telescope in 2030, the concept of a high resolution spectrograph for the VLT has been further explored, both for the science and technological aspects. Such an instrument will fill a gap in capabilities amongst the landscape of future instrumentation planned for the next decade. Its key characteristic will be high spectral resolution (R = 60000-80000) with multi-object (50-100) capabilities and, possibly, a stability that would provide high radial velocity precision (∼10m/s). In this work, we describe the science cases and driving science requirements for the instrument. Furthermore we will present some design solutions and technical options considered to meet these requirements.
KEYWORDS: Spectrographs, Stars, Chemical elements, Ultraviolet radiation, Telescopes, Galactic astronomy, Sensors, Astronomy, Signal to noise ratio, Near ultraviolet
In the era of Extremely Large Telescopes, the current generation of 8-10m facilities are likely to remain competitive at ground-UV wavelengths for the foreseeable future. The Cassegrain U-Band Efficient Spectrograph (CUBES) has been designed to provide high-efficiency (> 40%) observations in the near UV (305-400 nm requirement, 300-420 nm goal) at a spectral resolving power of R >20, 000 (with a lower-resolution, sky-limited mode of R ~7, 000). With the design focusing on maximizing the instrument throughput (ensuring a Signal to Noise Ratio (SNR) ~20 per high-resolution element at 313 nm for U ~18.5 mag objects in 1h of observations), it will offer new possibilities in many fields of astrophysics, providing access to key lines of stellar spectra: a tremendous diversity of iron-peak and heavy elements, lighter elements (in particular Beryllium) and light-element molecules (CO, CN, OH), as well as Balmer lines and the Balmer jump (particularly important for young stellar objects). The UV range is also critical in extragalactic studies: the circumgalactic medium of distant galaxies, the contribution of different types of sources to the cosmic UV background, the measurement of H2 and primordial Deuterium in a regime of relatively transparent intergalactic medium, and follow-up of explosive transients. The CUBES project completed a Phase A conceptual design in June 2021 and has now entered the detailed design and construction phase. First science operations are planned for 2028.
Alongside future observations with the new European Extremely Large Telescope (ELT), optimised instruments on the 8-10m generation of telescopes will still be competitive at ‘ground UV’ wavelengths (3000-4000 Å). The near UV provides a wealth of unique information on the nucleosynthesis of iron-peak elements, molecules, and neutron-capture elements. In the context of development of the near-UV CUBES spectrograph for ESO’s Very Large Telescope (VLT), we are investigating the impact of spectral resolution on the ability to estimate chemical abundances for beryllium and more than 30 iron-peak and heavy elements. From work ahead of the Phase A conceptual design of CUBES, here we present a comparison of the elements observable at the notional resolving power of CUBES (R ~ 20,000) to those with VLT-UVES (R ~ 40,000). For most of the considered lines signal- to-noise is a more critical factor than resolution. We summarise the elements accessible with CUBES, several of which (e.g. Be, Ge, Hf) are now the focus of quantitative simulations as part of the ongoing Phase A study.
In the era of Extremely Large Telescopes, the current generation of 8-10m facilities are likely to remain competitive at far-blue visible wavelengths for the foreseeable future. High-efficiency (<20%) observations of the ground UV (300- 400 nm) at medium resolving power (R~20,000) are required to address a number of exciting topics in stellar astrophysics, while also providing new insights in extragalactic science. Anticipating strong demand to better exploit this diagnostic-rich wavelength region, we revisit the science case and instrument requirements previously assembled for the CUBES concept for the Very Large Telescope.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.