SearcharxivSearch

arXiv subjects

William Sutherland

Publications and source records attributed to William Sutherland.

2 recordsLinked to original sources

WST, the Wide-field Spectroscopic Telescope: Telescope structure FE analyses

The Altitude Structure of the Wide-field Spectroscopic Telescope (WST) is designed to support and position both primary and secondary mirrors, made of structural steel. Due to its dimensions, the Altitude Structure is a substantial part of the WST facility, and its weight, performance, and dynamic behavior play a critical role in the functioning of the Telescope. This paper discusses the iterative process starting from the preliminary structural layout and leading to the optimization of the entire Structure. A Finite Element (FE) model was developed, defining the detailed dimensions and cross sections of each assembly's beams and plates under representative boundary conditions, in order to correctly simulate the operational environment. This model enables accurate estimation of structural weight, mechanical deformations, and stresses, as well as its frequency response for the evaluation of both local and global resonance modes. Based on the initial results obtained using preliminary beam cross sections and shell thickness, several assumptions were formulated to drive the mechanical optimization of the Altitude Structure. The outcome of this work consists of a refined structural configuration and the formulation of the governing design criteria.

astro-ph.IM

KiDS+VIKING-450: A new combined optical & near-IR dataset for cosmology and astrophysics

We present the curation and verification of a new combined optical and near infrared dataset for cosmology and astrophysics, derived from the combination of $ugri$-band imaging from the Kilo Degree Survey (KiDS) and $ZY\!J\!H\!K_{\rm s}$-band imaging from the VISTA Kilo degree Infrared Galaxy (VIKING) survey. This dataset is unrivaled in cosmological imaging surveys due to its combination of area ($458$ deg$^2$ before masking), depth ($r\le25$), and wavelength coverage ($ugriZY\!J\!H\!K_{\rm s}$). The combination of survey depth, area, and (most importantly) wavelength coverage allows significant reductions in systematic uncertainties (i.e. reductions of between 10 and 60\% in bias, outlier rate, and scatter) in photometric-to-spectroscopic redshift comparisons, compared to the optical-only case at photo-$z$ above $0.7$. The complementarity between our optical and NIR surveys means that over $80\%$ of our sources, across all photo-$z$, have significant detections (i.e. not upper limits) in our $8$ reddest bands. We derive photometry, photo-$z$, and stellar masses for all sources in the survey, and verify these data products against existing spectroscopic galaxy samples. We demonstrate the fidelity of our higher-level data products by constructing the survey stellar mass functions in 8 volume-complete redshift bins. We find that these photometrically derived mass functions provide excellent agreement with previous mass evolution studies derived using spectroscopic surveys. The primary data products presented in this paper are publicly available at http://kids.strw.leidenuniv.nl/.

astro-ph.CO