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E-ELT

HARMONI – the first light integral field spectrograph for the E-ELT. Niranjan Thatte On behalf of the HARMONI consortium. VLT. E-ELT. Outline. Capabilities of HARMONI AO science + modes Integral field + AO: an ideal marriage Acquisition time / observing efficiency. Modular Construction.

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E-ELT

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  1. HARMONI – the first light integral field spectrograph for the E-ELT Niranjan Thatte On behalf of the HARMONI consortium VLT E-ELT

  2. Outline • Capabilities of HARMONI • AO science + modes • Integral field + AO: an ideal marriage • Acquisition time / observing efficiency

  3. Modular Construction

  4. 20 mas 10 mas 4 mas 40 mas Best combination of sensitivity and spatial resolution Highest spatial resolution (diffraction limited) For extended sources & optimal FoV For optimal sensitivity (faint targets) 128 × 256 spaxels at all scales 5” × 10” 7 2.5” × 5” f 1.25” × 2.5” 0.5” × 1.0”

  5. Wavelength Ranges & Resolving Powers • Exploring adding simultaneous V-K coverage at R~500-1000 • Re-assessing the need for high spectral resolving power at visible wavelengths (< 0.8 micron)

  6. No ADC required • Integral field spectrograph does not require ADC, as each narrow wavelength channel can be re-aligned in software to compensate for atmsopheric refraction • Blurring within long exposure cannot be compensated post-facto, but improving detector performance allows many shorter exposures to be co-added without penalty.

  7. Different Flavours of AO SCAO GLAO LTAO Or even degraded GLAO (NGS only) !!!

  8. Contemporary Science Planets & Stars Stars & Galaxies Galaxies & Cosmology

  9. 5mas per pixel input 10 mas HARMONI scale 20 mas HARMONI scale 40 mas HARMONI scale 100 mas scale on VLT

  10. High-z Ultra-luminous IR Galaxies H in z=2 ULIRG Survey 50 Spitzer candidate ULIRGs 1<z<2.5 Detect & characterise nuclear disks & rings Measure shocks, winds, interaction with IGM Measure dynamical masses Distribution of dust Modes of star formation Measure rotation, masses, dust content, stellar pops & FP Requires: diffraction limited R > 4000 spectra, spaxels 5-40mas. @  0.5 - 2.5.

  11. Optimal Spaxel Scale • 15-20mas is optimal spaxel size for LTAO point sources • Need to re-compute as a function of wavelength using 39m E-ELT, latest telescope PSFs, and HARMONI design

  12. SCAO • Provides significantly higher Strehl on-axis (70% v/s 48.5% in K band, median seeing) • De-risk LTAO (complex, untested on sky) • Key science themes • Characterisation of exo-planets detected by SPHERE / GPI • Detailed studies of outer Solar System (Jovian moons, Neptune, Uranus => see talk by Fraser Clarke Fri morning) • Serendipitous targets (high z galaxies, need ancillary data!)

  13. Spectroscopy at the Diffraction Limit • Instrument designed for coarse (seeing-limited) spaxelsgives excellent performance at diffraction limited scales, even including slit diffraction. 56mas pupil size (grating physical size) 4mas anamorphic pupil size (ignoring diffraction)

  14. High? Contrast with HARMONI • M4 actuator density similar to NACO & SINFONI on VLT, expect similar peak Strehl to SINFONI (~70% in K) • At these Strehl’s, benefit of coronagraph as a diffraction suppression system remains to be demonstrated • ADC would be needed to gain from coronagraph. • Apodizer, followed by large field stop (many λ/D) might work better. • Occulting bar to get around persistence / duty cycle issues • Looking into prism disperser for low R, wide band use. • ADI type operation possible, but co-rotate occulting bar?

  15. PSF effects • Parameterize PSF (axi-symmetric) with a few parameters, which vary smoothly with wavelength => see Poster by S. Zieleniewski • Allows quick computation of PSF at any wavelength, with high accuracy. Strong variation of PSF with wavelength

  16. PSF Reconstruction

  17. 10€ / second! • Amortised cost of E-ELT 10x larger than VLT • Need to optimise acquisition time / open-shutter efficiency of science instrument • Eliminate • Background sky exposures • Need for telluric calibrators (on-sky) • PSF calibration observations • Blind offsets from reference stars (don’t use long slits!!) • Hunting for tip-tilt stars / NGS reference stars

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