Five categories of observations with ELTs andtheir impact on the instrumentation Tim Hawarden, Colin Cunnigham (UKATC) Andreas Quirrenbach (Leiden) Michael Redfern (Galway) Roland Bacon (Lyon) Callum Norrie (UKATC), Suzanne Ramsay Howat
Why an instrumentation study? • To explore interaction between the telescope design and instrument design for an ELT • Do we need a gravity stable platform? • What are the wavefront sensing requirements? • To plan for the required technology developments • Considered from two angles: • selecting instruments which are required by the science case and which are a challenge for the telescope; • considering categories of observation and how these drive the suite of instruments. See papers by Russell and Hawarden, 2nd Backaskog Workshop.
3 POINT DESIGN STUDIES • WFSPEC – Wide Field seeing-limited (or boundary-layer corrected) SPECtrometer • Wide field=huge instrument and seeing limited pixel scale a challenge to the instrument designers! • MIDIR – MID-IR diffraction-limited high-resolution spectrometer/imager • Diffraction limited imaging at MIR wavelengths a strength of any ELT, but what about site choice and emissivity? • MOMSI – Optical/NIR Multi-Object & Multi-field Spectrometer & Imager • 100s-1000s of objects, highly modular instrument?
Point Design Deliverables • Link to the Science Case (SRD) • Functions and Performance Requirements Document (FPRD) • Design drivers on Telescope and AO systems • Outline Design of instrument • indicating mass, volume, moments, handling, data rates etc • Technical Risk Analysis • Outline Project Plan
Point Design Deliverables (2) • Indicative costing, with effort (FTE) and hardware requirements • Operational Concepts Definition Document • Calibration requirements statement • Performance Simulator • Assessment of resource requirements • NB NOT full scientific suite of instruments or full instrument designs • Parallel endeavour to the ESO instrument studies
…and 6 Small Studies • Planet Finder – High dynamic-range (coronagraphic) imager/spectrometer • HISPEC – O/NIR high spectral resolution instrument • HiTRI -- High Time Resolution Instrument • GRB-Catcher -- Fast-response broad-band imaging spectrometer for transients • SCOWL (talk by Bill Dent) • Atmospheric Dispersion Correction (talk by Eli Atad) • Innovative instrument designs search
SMALL STUDIES • General picture of practicability of instrument type on 50-100m ELT • Identify early problems • Begin to solve generic problems (e.g. AO-ADC or AODC)
Five observational categories • Previously-known widely-spaced objects: << 1 arcmin-2: one per telescope pointing • Previously-known moderately-spaced objects: >1 arcmin-2: ~10 per pointing • Previously-known closely spaced objects: >>10 arcmin-2: 100s per pointing • As-yet-undiscovered medium-to-closely spaced objects: ~1 to >>100 per pointing • Objects arranged in very extended structures: >> 2 arcmin
Category 1 • Previously-known widely-spaced objects: << 1 arcmin-2, one per telescope pointing • Spectroscopy of very high redshift (z = 6 – 20) “first generation” objects such as GRB afterglows, Population III Supernovae (SNe) and QSOs • Spectroscopy of galaxies in the re-ionisation era (Lyman-Break Galaxy analogues) • Imaging and spectroscopy of asteroids and comets • Imaging and spectroscopy of the outer planets and moons of the major planets • The study of planets around nearby stars
Case study: Terrestrial planets • Requirements: ~1’’x1’’ FOV, diffraction limited imaging, moderate resolving power (500-1000); 0.6-1.4mm From Hainaut, Rahoui & Gilmozzi (2004).
PLANET FINDER • Segmentation effects • Diffraction structures (static hexagonal array of mini-PSFs (~10-5 to 10-4 of central peak): lots of gaps, but during exposure- • smearing may leave little room for finding planets at 10-10 • Speckle effects: Quasi-static or variable at seeing frequency? Simulation from E-ELT science case, by ESO AO group.
PLANET FINDER • Challenges • Stray light suppression, coronagraphic removal of the bright source, maximum possible starlight in the image core by very high-order AO (Strehl ratios >0.7 are sought) • Spectroscopy will be hard and NIR photon-counting detectors are likely to be important
Category 2 • Previously-known moderately-spaced objects: • Studies of stellar populations in nearby galaxies to reveal details of systems which have merged to form the present-day galaxy • Photometric (spectroscopic) monitoring of distant supernovae at about 6 (3) per MCAO field • high redshift galaxies, for studies of the physical processes
Physics of high z galaxies • Requirements: >2’x2’ FOV, 0.05” resolution, R~5000, 0.5-2.5mm, Multi-IFUs • VLT KMOS clone? Physical processes in galaxies from E-ELT Science case, after Carlos Frenk.
Category 3. • Previously-known closely spaced objects: • High-resolution imaging and, especially, spectroscopy of objects revealed by HST and JWST. The Hubble Ultra-Deep Field contains about 900 galaxies per square arcminute, down to R ~29 • Spatially resolved spectroscopic observations of galaxies at high and very high redshifts to confirm their natures, kinematics and composition and to track their changes with redshift
MOMSI:multi-object, multi-IFU spectrometer and imager Requirements: functionally equivalent to many KMOS-clones: MOMSI with 100 > 100s pick-offs See talk tomorrow
Category 4 • As-yet-undiscovered moderately spaced objects: • Identification of high-redshift SNe for photometric and spectroscopic monitoring • Identification of the products of first-generation objects such as GRB glows, Pop III SNE and QSOs for spectroscopy • Instrument: 2x2 arcmin diffraction limited imaging 2-4000 IR arrays? Not studied currently
Category 5 • Objects arranged in very extended structures: • Study of the roles, properties and evolution of dark-matter haloes and baryonic matter during galaxy formation at early epochs • the 3-D evolution of Large-Scale Structure
Assembly ofgalaxy haloes Requirements: wide-field (~10 arcmin) mode of operation, providing GLAO and “button AO” Image from Abadi et al 2003 and E-ELT science case.
WFSPEC challenges • Challenges • Matching a seeing-limited image (or even a BLC image) to a reasonably small number of detector pixels is hard! Need either: • Impossibly fast final F/ratios (for D=100m, need ~ f/0.2 to put 0."3 on a 30 µm array pixel), or • much larger physical pixels than currently in use (150µm for a final f/1.0) • use of smaller (sub)pupils
Conclusions • Point Design studies begin in September • Merge with the OWL instrument studies • Studies will focus science case on practical capabilities of instruments • Many scientific goals push the instrument FOV, spatial and spectral resolution in mutually incompatible directions • Studying the instrumentation at this early stage will strengthen the ELT projects