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WEAVE The Next-Generation Wide Field Spectroscopy Facility fo r the WHT

Gavin Dalton ( RALSpace /Oxford) SPIE Amsterdam 8466-23. WEAVE The Next-Generation Wide Field Spectroscopy Facility fo r the WHT . + 115 members of the science team across Europe. Background. Community discussion meetings in early 2010 Summarised in Balcells et al. 2010 (SPIE)

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WEAVE The Next-Generation Wide Field Spectroscopy Facility fo r the WHT

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  1. Gavin Dalton (RALSpace/Oxford) SPIE Amsterdam 8466-23 WEAVEThe Next-Generation Wide Field Spectroscopy Facility for the WHT

  2. + 115 members of the science team across Europe

  3. Background • Community discussion meetings in early 2010 • Summarised in Balcells et al. 2010 (SPIE) • Push for a new wide-field MOS instrument scoped for Gaia/LOFAR follow-up. • Phase A KO at SPIE 2010 • PDR phase 09/2011—02/2012 + 115 members of the science team across Europe.

  4. Science Overview Key science themes from community workshops: • What are the stellar content and stellar distribution in the Milky Way? • What is the nature of dark matter and dark energy? • How do galaxies form and evolve? • What are the contents, internal structures, and mechanisms of galaxies? • What is the role of environment and interactions in galaxy evolution?

  5. WEAVE/Gaia Survey Space WEAVE, R~5000 370-1000nm δvr < 5kms-1 δ[Fe/H] < 0.2 dex >106 stars 10000 deg2 Enough to measure Metallicity Distribution Function Figure courtesy Vanessa Hill, OCA

  6. WEAVE/Gaia Survey Space WEAVE, R~20000 δvr < 1kms-1 δ[Fe/H] < 0.1 dex 500 streams 50,000 halo giants 2500 deg2 Chemicallabellingof stars by distinct formation events

  7. Cosmological Surveys What is dark energy and (how) does it evolve? 0.1% in growth rate, 0.7% on dH(z) 0.4% on dA(z) • Select galaxies from LOFAR continuum surveys 30,60,120 & 200MHz (0.1mJy) • ~10000 deg2, radio continuum detections (no redshifts) • ~107 targets, z<1.3 (Ha/OII) & z>2.3 (Lya) • Strongly biased towards star forming galaxies… >10M/year at z=0.5, easily detectable with WEAVE • BAO survey with high (>80%) redshift success rate in ~800 nights (c.f. 30% success rate implied for FMOS surveys based on broad-band colour selection) • R=5000: easy to work in the OH forest at 900nm

  8. Galaxy Evolution: WEAVE/APERTIF Connect galaxy evolution to internal and external effects: Couple internal motions and stellar content to neutral gas and large-scale environment APERTIF:set of phased array detectors at the Westerbork Synthesis Radio Telescope... Northern Hemisphere SKA pathfinder. APERTIF Medium Deep Survey 500 square degrees, 104 galaxies z<0.4 with full HI velocity maps Correlate HI velocity maps with stellar populations and star formation using WEAVE IFUs Nearby targets observed with a single large IFU HETDEX H-ATLAS CVn groups Nearby Galaxy

  9. Current Layout of the WHT Current top-end flip-ring GHRIL enclosure, WYFFOS spectrograph GRACE enclosure, NAOMI/OASIS

  10. Top level specs

  11. Instrument Overview…

  12. New Prime Focus Corrector • 2 degree diameter field of view (f/2.7) • 1000mm first lens • 270mm back focal distance • Counter-rotating ADC • Polychromatic image quality degrades by only 0.1” at 55 degrees ZD with ADC. • Flat focal plane with tolerable (<2.5° non-telecentricity N-BK7, N-BK7/LLF1, N-BK7/LLF1, N-FK5 Poster 8444-251 (T. Agocs, Tuesday)

  13. Prime Focus Corrector & ADC Initial mounting concept integrates PFC directly to the ring to save mass Presents a challenge for alignment and stability..

  14. Prime Focus Corrector & ADC Better option is to mount the corrector within the centre-section

  15. Fits inside the available vertical space envelope… (just clears the crane gantry) Positioner Total positioner mass ~800kg (including anti-vibration Counterweights) Obstruction diameter ~1.6m Tumbler clears corrector by ~10mm Positioner 1 Positioner 2 Sky Camera Fibre wrap

  16. Positioner Positioner represents a large off-axis load on the inner ring, but mass/balance managed to be close to current values.

  17. Retractor Concept Push park locations beyond the useful field edge to ease accomodation of 1000 fibres. Triple-parking concept. –Optimal choice to allow sufficient structure for discrete units

  18. FIELD SIMULATION Random target distribution, oversampled (1800 targets) Reconfiguration simulations imply ~1750 moves to reconfigure…, but some optimisation still to be done… Conservative 2-robot simulation suggests a gain of >80% 8 Guide ‘fibres’/field are coherent image bundles (FOV ~4”). Demand position must be tracked during the exposure to follow differential refraction

  19. Button Input Geometry 85μm 1.3” =75μm

  20. Poster 8450-127 (I. Guinouard, Tuesday) WEAVE IFUs • Use the full available slit length of the spectrograph. • 20-30 small field IFUs, same fibre size as MOS • 50-30 fibres/unit, e.g. • Large single-field IFU uses full slit length in a single IFU located at 90° tumbler position IFUs stored on one MOS field plate, at the cost of a small number of MOS science fibres. Physical size of IFU unit still governed by 57μm/” plate scale, so still only a few mm button size. 12.4” 14.7” 1.3” 1.5” 7.8” 9”

  21. WEAVE IFUs • Use the full available slit length of the spectrograph. • Large single-field IFU uses full slit length in a single IFU located at 90° tumbler position • ~550 2.6” fibres in a SPARSE-PAK geometry • Offset bundles for skysubtraction • Fixed dedicated autoguider unit

  22. f/3.0 input, f/1.8 camera, 190mm beam diameter. 2x8kx3k e2V CCDs (CCD231-68) in each camera. Dual-Beam Spectrograph Design Slit curved to give uniform spectral coverage for all fibres in low-res 7-lens cameras (3 aspheres) 16k spectral pixels, R=5000 over 370—1000nm in one shot Camera lenses are F2, LLF1, N-FK51A, and LAK9 Some vignetting allowed in high res

  23. f/3.0 input, f/1.8 camera, 190mm beam diameter. 2x8kx3k e2V CCDs (CCD231-68) in each camera. Dual-Beam Spectrograph Design Slit curved to give uniform spectral coverage for all fibres in low-res 7-lens cameras (3 aspheres) 16k spectral pixels, R=5000 over 370—1000nm in one shot Camera lenses are F2, LLF1, N-FK51A, and LAK9 Some vignetting allowed in high res Slits exchanged vertically

  24. Throughput

  25. High-res Low-res WEAVE as a survey instrument

  26. WEAVE TIMELINE • Forward look for WHT now determined • WEAVE is the centrepiece through to 2022 • PDR Feb 2013 • Goal is to complete construction and be on-sky for science in early 2017. • 5 years of operations 1.3x107 high quality spectra (data pipeline based on CASU development for ESO-Gaia VLT FLAMES survey)

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