Testing process for the WEAVE prime focus corrector lenses for the William Herschel Telescope

Proceedings of SPIE - The International Society for Optical Engineering 10700 (2018)

D Bogunovic, G Jonas, D Cochrane, A Rakich, P Connor, A Romeril, J Romeril, L Gers, E Howick, C Young, T Reed, I Tosh, É Lhomé, KM Dee, G Dalton, S Trager, JAL Aguerri, P Bonifacio, A Vallenari, E Carrasco, DC Abrams, K Middleton

© 2018 SPIE. A new prime focus corrector for the WEAVE project for the William Herschel Telescope is being produced. The corrector consists of six lens elements, the largest being 1.1 m in diameter. It also incorporates an Atmospheric Dispersion Corrector. Testing procedures for the WEAVE prime focus corrector lens elements are described here. Critical issues encountered in practice, including the influence of the lens size, wedge and weight on the testing procedure are discussed. Due to large lens dimensions, a dedicated test tower and lens support system has been developed to measure the optical surface form errors of the concave surfaces and the transmitted wavefront of each lens. For some of the lens elements, sub-aperture measurements have been performed using an off-axis Hindle sphere and the resultant OPD maps have been stitched together. The challenge of testing a wedged lens with a combination of a long radius convex surface and a short radius concave surface has been resolved by using another lens from the system as an auxiliary lens. The practice of testing convex surfaces via internal reflection/transmission through the lens element has been avoided entirely in this case and some discussion justifying the choices of metrology approach taken is given. The fabrication and acceptance testing of the lens elements has been completed within the expected time and budget, and all elements have been shown to meet requirements.

VIRUS: status and performance of the massively-replicated fiber integral field spectrograph for the upgraded Hobby-Eberly Telescope

Proceedings of SPIE - The International Society for Optical Engineering Society of Photo-optical Instrumentation Engineers (2018)

G Hill, G Dalton

The ELT-MOS (MOSAIC): Towards the construction phase

Proceedings of SPIE - The International Society for Optical Engineering 10702 (2018)

S Morris, F Hammer, P Jagourel, CJ Evans, M Puech, GB Dalton, M Rodrigues, R Sanchez-Janssen, E Fitzsimons, B Barbuy, JG Cuby, L Kaper, M Roth, G Rousset, R Myers, O Le Fèvre, A Finogenov, J Kotilainen, B Castilho, G Ostlin, S Feltzing, A Korn, J Gallego, Á Castillo, J Iglesias-Páramo, L Pentericci, B Ziegler, J Afonso, M Dubbledam, M Close, P Parr-Burman, TJ Morris, F Chemla, F De Frondat, A Kelz, I Guinouard, IJ Lewis, K Middleton, R Navarro, M Larrieu, J Pragt, A Janssen, K Dohlen, K El Hadi, É Gendron, Y Yang, M Wells, JM Conan, T Fusco, D Schaerer, E Bergin, S Taburet, M Frotin, N Berkourn

© 2018 SPIE. When combined with the huge collecting area of the ELT, MOSAIC will be the most effective and flexible Multi-Object Spectrograph (MOS) facility in the world, having both a high multiplex and a multi-Integral Field Unit (Multi-IFU) capability. It will be the fastest way to spectroscopically follow-up the faintest sources, probing the reionisation epoch, as well as evaluating the evolution of the dwarf mass function over most of the age of the Universe. MOSAIC will be world-leading in generating an inventory of both the dark matter (from realistic rotation curves with MOAO fed NIR IFUs) and the cool to warm-hot gas phases in z=3.5 galactic haloes (with visible wavelenth IFUs). Galactic archaeology and the first massive black holes are additional targets for which MOSAIC will also be revolutionary. MOAO and accurate sky subtraction with fibres have now been demonstrated on sky, removing all low Technical Readiness Level (TRL) items from the instrument. A prompt implementation of MOSAIC is feasible, and indeed could increase the robustness and reduce risk on the ELT, since it does not require diffraction limited adaptive optics performance. Science programmes and survey strategies are currently being investigated by the Consortium, which is also hoping to welcome a few new partners in the next two years.

First lab results of the WEAVE fibre positioner system

Proceedings of SPIE - The International Society for Optical Engineering 10702 (2018)

E Schallig, IJ Lewis, G Dalton, M Brock, D Terrett, DC Abrams, K Middleton, G Bishop, JAL Aguerri, P Bonifacio, E Carrasco Licea, SC Trager, A Vallenari

© 2018 SPIE. WEAVE is the new wide-field spectroscopy facility for the prime focus of the William Herschel Telescope on La Palma in the Canary Islands, Spain. It is a multi-object "pick-and-place" fibre-fed spectrograph with a 960 fibre multiplex behind a new dedicated 2° prime focus corrector. We provide an update on the fibre positioner's technical progress. The hardware has been fully assembled and integrated with its control system for testing. We have made initial calibrations and are starting to move test fibres. In the near future we will dismantle for final modifications and surface anodising, before final reassembly and full fibre installation.

Simulating surveys for ELT-MOSAIC: Status of the MOSAIC science case after phase A

Proceedings of SPIE - The International Society for Optical Engineering 10702 (2018)

M Puech, CJ Evans, K Disseau, J Japelj, OH Ramírez-Agudelo, H Rahmani, M Trevisan, JL Wang, M Rodrigues, R Sánchez-Janssen, Y Yang, F Hammer, L Kaper, SL Morris, B Barbuy, JG Cuby, G Dalton, E Fitzsimons, P Jagourel

© 2018 SPIE. We present the consolidated scientific case for multi-object spectroscopy with the MOSAIC concept on the European ELT. The cases span the full range of ELT science and require either '?high multiplex' or '?high definition' observations to best exploit the excellent sensitivity and wide field-of-view of the telescope. Following scientific prioritisation by the Science Team during the recent Phase A study of the MOSAIC concept, we highlight four key surveys designed for the instrument using detailed simulations of its scientific performance. We discuss future ways to optimise the conceptual design of MOSAIC in Phase B, and illustrate its competitiveness and unique capabilities by comparison with other facilities that will be available in the 2020s.

Photometric redshifts for the next generation of deep radio continuum surveys - II. Gaussian processes and hybrid estimates


KJ Duncan, MJ Jarvis, MJI Brown, HJA Rottgering

Radial measurements of IMF-sensitive absorption features in two massive ETGs


SP Vaughan, RL Davies, S Zieleniewski, RCW Houghton

Donald Lynden-Bell (1935-2018).

Nature 555 (2018) 166-

R Davies

KiDS-i-800: comparing weak gravitational lensing measurements from same-sky surveys


A Amon, C Heymans, D Klaes, T Erben, C Blake, H Hildebrandt, H Hoekstra, K Kuijken, L Miller, CB Morrison, A Choi, JTA de Jong, K Glazebrook, N Irisarri, B Joachimi, S Joudaki, A Kannawadi, C Lidman, N Napolitano, D Parkinson, P Schneider, E van Uitert, M Viola, C Wolf

LOFAR/H-ATLAS: the low-frequency radio luminosity-star formation rate relation


G Gurkan, MJ Hardcastle, DJB Smith, PN Best, N Bourne, G Calistro-Rivera, G Heald, MJ Jarvis, I Prandoni, HJA Rottgering, J Sabater, T Shimwell, C Tasse, WL Williams

The VANDELS ESO public spectroscopic survey: Observations and first data release


L Pentericci, RJ McLure, B Garilli, O Cucciati, P Franzetti, A Iovino, R Amorin, M Bolzonella, A Bongiorno, AC Carnall, M Castellano, A Cimatti, M Cirasuolo, F Cullen, S De Barros, JS Dunlop, D Elbaz, SL Finkelstein, A Fontana, F Fontanot, M Fumana, A Gargiulo, L Guaita, WG Hartley, MJ Jarvis, S Juneau, W Karman, D Maccagni, F Marchi, E Marmol-Queralto, K Nandra, E Pompei, L Pozzetti, M Scodeggio, V Sommariva, M Talia, O Almaini, I Balestra, S Bardelli, EF Bell, N Bourne, RAA Bowler, M Brusa, F Buitrago, KI Caputi, P Cassata, S Charlot, A Citro, G Cresci, S Cristiani, E Curtis-Lake, M Dickinson, GG Fazio, HC Ferguson, F Fiore, M Franco, JPU Fynbo, A Galametz, A Georgakakis, M Giavalisco, A Grazian, NP Hathi, I Jung, S Kim, AM Koekemoer, Y Khusanova, O Le Fevre, JM Lotz, F Mannucci, DT Maltby, K Matsuoka, DJ McLeod, H Mendez-Hernandez, J Mendez-Abreu, M Mignoli, M Moresco, A Mortlock, M Nonino, M Pannella, C Papovich, P Popesso, DP Rosario, M Salvato, P Santini, D Schaerer, C Schreiber, DP Stark, LAM Tasca, R Thomas, T Treu, E Vanzella, V Wild, CC Williams, G Zamorani, E Zucca

Improving photometric redshift estimation using GPz: size information, post processing, and improved photometry


Z Gomes, MJ Jarvis, IA Almosallam, SJ Roberts

LOFAR-Bootes: properties of high- and low-excitation radio galaxies at 0.5 < z < 2.0


WL Williams, GC Rivera, PN Best, MJ Hardcastle, HJA Rottgering, KJ Duncan, F de Gasperin, MJ Jarvis, GK Miley, EK Mahony, LK Morabito, DM Nisbet, I Prandoni, DJB Smith, C Tasse, GJ White

A photometric analysis of Abell 1689: two-dimensional multistructure decomposition, morphological classification and the Fundamental Plane


ED Bonta, RL Davies, RCW Houghton, F D'Eugenio, J Mendez-Abreu

Radio weak lensing shear measurement in the visibility domain - II. Source extraction

Monthly Notices of the Royal Astronomical Society 476 (2018) 2053-2062

M Rivi, L Miller

© 2018 The Author(s). This paper extends the method introduced in Rivi et al. (2016b) to measure galaxy ellipticities in the visibility domain for radio weak lensing surveys. In that paper, we focused on the development and testing of the method for the simple case of individual galaxies located at the phase centre, and proposed to extend it to the realistic case of many sources in the field of view by isolating visibilities of each source with a faceting technique. In this second paper, we present a detailed algorithm for source extraction in the visibility domain and show its effectiveness as a function of the source number density by running simulations of SKA1-MID observations in the band 950-1150 MHz and comparing original and measured values of galaxies' ellipticities. Shear measurements from a realistic population of 104 galaxies randomly located in a field of view of 1 deg2(i.e. the source density expected for the current radio weak lensing survey proposal with SKA1) are also performed. At SNR ≥ 10, the multiplicative bias is only a factor 1.5 worse than what found when analysing individual sources, and is still comparable to the bias values reported for similar measurement methods at optical wavelengths. The additive bias is unchanged from the case of individual sources, but it is significantly larger than typically found in optical surveys. This bias depends on the shape of the uv coverage and we suggest that a uv-plane weighting scheme to produce a more isotropic shape could reduce and control additive bias.

Emergent dark energy from dark matter

PHYSICAL REVIEW D 97 (2018) ARTN 121301

T Kobayashi, PG Ferreira

KiDS-450+2dFLenS: Cosmological parameter constraints from weak gravitational lensing tomography and overlapping redshift-space galaxy clustering


S Joudaki, C Blake, A Johnson, A Amon, M Asgari, A Choi, T Erben, K Glazebrook, J Harnois-Deraps, C Heymans, H Hildebrandt, H Hoekstra, D Klaes, K Kuijken, C Lidman, A Mead, L Miller, D Parkinson, GB Poole, P Schneider, M Viola, C Wolf

VIRUS: Status and performance of the massively replicated fiber integral field spectrograph for the upgraded Hobby-Eberly Telescope

Proceedings of SPIE - The International Society for Optical Engineering 10702 (2018)

GJ Hill, A Kelz, H Lee, P MacQueen, TW Peterson, J Ramsey, BL Vattiat, DL Depoy, N Drory, K Gebhardt, JM Good, T Jahn, H Kriel, JL Marshall, SE Tuttle, G Zeimann, E Balderrama, R Bryant, B Buetow, TS Chonis, G Damm, MH Fabricius, D Farrow, JR Fowler, C Froning, DM Haynes, BL Indahl, J Martin, F Montesano, E Mrozinski, H Nicklas, E Noyola, S Odewahn, A Peterson, T Prochaska, S Rostopchin, M Shetrone, G Smith, JM Snigula, R Spencer, A Westfall, T Armandroff, R Bender, G Dalton, M Steinmetz

© 2018 SPIE. The Visible Integral-field Replicable Unit Spectrograph (VIRUS) consists of 156 identical spectrographs (arrayed as 78 pairs, each with a pair of spectrographs) fed by 35,000 fibers, each 1.5 arcsec diameter, at the focus of the upgraded 10 m Hobby-Eberly Telescope (HET). VIRUS has a fixed bandpass of 350-550 nm and resolving power R∼750. The fibers are grouped into 78 integral field units, each with 448 fibers and 20 m average length. VIRUS is the first example of large-scale replication applied to optical astronomy and is capable of surveying large areas of sky, spectrally. The VIRUS concept offers significant savings of engineering effort and cost when compared to traditional instruments. The main motivator for VIRUS is to map the evolution of dark energy for the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX), using 0.8M Lyman-alpha emitting galaxies as tracers. The VIRUS array has been undergoing staged deployment starting in late 2015. Currently, more than half of the array has been populated and the HETDEX survey started in 2017 December. It will provide a powerful new facility instrument for the HET, well suited to the survey niche of the telescope, and will open up large spectroscopic surveys of the emission line universe for the first time. We will review the current state of production, lessons learned in sustaining volume production, characterization, deployment, and commissioning of this massive instrument.

A general theory of linear cosmological perturbations: stability conditions, the quasistatic limit and dynamics


M Lagos, E Bellini, J Noller, PG Ferreira, T Baker

The dipole anisotropy of AllWISE galaxies

Monthly Notices of the Royal Astronomical Society Blackwell Publishing Inc. 477 (2018) 1772-1781

M Rameez, R Mohayaee, S Sarkar, J Colin

We determine the dipole in the WISE galaxy catalogue. After reducing star contamination to <0.1% by rejecting sources with high apparent motion and those close to the Galactic plane, we eliminate low redshift sources to suppress the non-kinematic, clustering dipole. We remove sources within {\pm}5{\deg} of the super-galactic plane, as well as those within 1'' of 2MRS sources at redshift z < 0.03. We enforce cuts on the source angular extent to preferentially select distant ones. As we progress along these steps, the dipole converges in direction to within 5{\deg} of the CMB dipole and its magnitude also progressively reduces but stabilises at {\sim}0.012, corresponding to a velocity >1000 km/s if it is solely of kinematic origin. However, previous studies have shown that only {\sim}70% of the velocity of the Local Group as inferred from the CMB dipole is due to sources at z < 0.03. We examine the Dark Sky simulations to quantify the prevalence of such environments and find that <2.1% of Milky Way-like observers in a {\Lambda}CDM universe should observe the bulk flow (> 240 km/s extending to z > 0.03) that we do. We construct mock catalogues in the neighbourhood of such peculiar observers in order to mimic our final galaxy selection and quantify the residual clustering dipole. After subtracting this the remaining dipole is 0.0048 {\pm} 0.0022, corresponding to a velocity of 420 {\pm} 213 km/s which is consistent with the CMB. However the sources (at z > 0.03) of such a large clustering dipole remain to be identified.