Oliver Czoskefor the Consortium

MICADOInstrument Data Simulator

Wien, 15 December 2015“From Ground to Space: Astronomical Instrumentation as a Window to the Universe”

The European Extremely Large Telescope (E-ELT)

(Source: ESO)

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MICADO Key Capabilities

Imaging:• 0.8− 2.4 µm with > 30 broad/narrow filters• 1.5 & 4 mas pixels for 19′′ and 51′′ FoV at 6− 12 mas resolution• similar sensitivity to JWST, 6× better resolution

Astrometric Imaging:• 50 µas precision across full field• 10 µas/yr = 5 km/s at 100 kpc after 3–4 years

Spectroscopy:• fixed configuration for 0.8− 1.45 µm and 1.45− 2.5 µm• R ∼ 8000 across slit, higher for point sources

High-contrast Imaging:• focal plane coronagraph & Lyot stop• angular differential imaging• small inner working angle

Time-resolved Astronomy:• windowing for frame rates up to ∼ 100 Hz

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MICADO Science

Imaging:

• cosmic star-formation history: resolved stellar populations• structure of high-z galaxies on 100 pc scales• nuclei of nearby galaxies (stellar cusps, star formation, black holes)

Astrometric Imaging:

• stellar motions within light hours of Sgr A∗

• intermediate-mass black holes in stellar clusters and dwarf galaxies• Milky Way formation: proper motion of clusters and dwarf galaxies

Spectroscopy:

• ages, metallicities, central dispersions of first elliptical galaxies at z = 2− 3• spectra of first supernovae at z = 1− 6• redshifts, velocities, metallicities of star-forming galaxies at z = 4− 6

High-contrast Imaging:

• Giant/massive planets at a few AU around nearby stars• Direct detection of planets discovered via RV measurements

Time-resolved Astronomy:

• Pulsars, magnetars; compact binaries; accreting white dwarfs; transits, occultations4

Point source detectability

Kieran Leschinski

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MICADO: Structure

Shown: Stand-alone phase (SCAO)Later: MAORY for MCAO

Cryostat & derotator

Fold mirror & calibration unit

SCAO(+ MAORY NGS-WFS)

Electronics(co-rotating)

Cable wrap MICADO Consortium

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MICADO: Optics

Optical Bench 1

Optical Bench 2

Rotating Bench

Mechanism Bench

Cryo-Window

Collimator Optics

Focal Plane E-ELT (grey)

Focal Plane MICADO (red)

Camera Optics

Various switchable

optics

MICADO Consortium

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MICADO: Optics

A. 1.5mas imager (4 fixed mirrors)

C. Cross-dispersed Spectroscopy (2 gratings)

B. 4mas imager (2 flat fold mirrors)

D. Pupil imager (2 flat fold mirrors + 1 lens)

Switchable optics

MICADO Consortium

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Focal-Plane Array/Detectors

• 3× 3 HAWAII-4RG (HgCdTe)detectors (each 4096× 4096 pixels)

• Camera provides two pixel scale:

? 4 mas/pixel (standard)? 1.5 mas/pixel (zoom)

• Cross-dispersed spectroscopy:complex order layout in detectorplane

51.5" / 19.3"

50.7

" /

19.0

"

I/J H/K

MICADO Consortium Tele

dyne

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Micado: Timeline

6 October 2015 Phase-B Kick-off at consortium meeting in Vienna

October 2018 Preliminary Design Review

October 2020 Final Design Review

ca. 2025 Operational at E-ELT

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SimCADO: Instrument data simulator for MICADO

Why an instrument data simulator?• MICADO is a complex instrument consisting of many subsystems• Detailed simulations of subsystems need to be integrated into a

model of the instrument as a whole.• Focus on data, the ultimate product of MICADO.

SimCADO

Science team

• Develop detailedscience cases

General user

• Feasibility ofobservations

Software development

• data-reduction pipeline• conformity to ESO DFS

standards

Hardware development

• trade-off studies

Calibration plan

• calibration in hardwareor software?

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SimCADO: Design Goals

Flexibility: nothing– easily update, replace or add components– switch off or use lighter versions of certain effects according to interests

of user

Usability: nothingusable by everyone on a reasonable desktop computer in a reasonableamount of time

Reliability: nothingtest SimCADO on existing instruments (HAWK-I, without and with AOF)

=⇒ modular software design=⇒ array-based approach (data cubes)=⇒ implementation in python, core functions in C=⇒ two-phase development:

1. produce “perfectly reduced data” (ETC++)2. include instrumental effects, produce raw detector frames (science

and calibration)

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SimCADO: The MICADO Data Simulator

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Atmosphere

The Innsbruck project in the Austrian In-kind contribution dealt with atmo-spheric modelling and resulted in three publicly available products:

• molecfit: modelling of the telluric absorption spectrum from 300 nm to30 µm (based on LBLRTM radiative transfer code, HITRAN molecular linedatabase)

• skycorr: sky emission subtraction for observations without plain sky in-formation

• skycalc: Cerro Paranal sky model producing sky emission and transmis-sion spectra (up to R = 106). Includes:

? molecular emission of lower atmosphere? emission lines of upper atmosphere? airglow continuum (residual continuum)? scattered moonlight? zodiacal light

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Atmosphere: transmission spectrum

1.780 1.785 1.790 1.795 1.800Wavelength (um)

0.2

0.4

0.6

0.8

1.0

Tra

nsm

issi

vit

y

R=60 000Summer (Dec/Jan)Winter (Jun/Jul)

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Atmosphere: emission spectrum

1.600 1.605 1.610 1.615 1.620 1.625 1.630Wavelength (um)

102

103

104

105

106

107

Em

issi

on (

photo

ns/

s/m

2/u

m/a

rcse

c2)

1/3 of night2/3 of night3/3 of night

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SimCADO: The MICADO Data Simulator

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Distortion

Distortion map from E-ELT focal plane to MICADO focal-plane array(4 mas imaging mode)

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SimCADO: The MICADO Data Simulator

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Putting the cube onto the detector: Photon noise

IR detectors can be read out non-destructively=⇒ up-the-ramp sampling (or other scheme)

●

●

●

●

●

●

●

●

●

●

0 2 4 6 8 10

020

4060

80

time

Acc

um. s

igna

l

Poisson model σ2γ = 〈Nγ〉 not correct:

underestimates noise by ∼ 10%

6 8 10 12 140.

00.

10.

20.

30.

40.

5

Flux estimate

Den

sity

Mean: 10 photons/sample10000 realizations

single integration (Poisson)σ = 0.99910 samples during integrationσ = 1.094

Detector non-linearity: use measurements from existing detectors

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Detector noise sources

HAWK-I, chip 1, raw dark frames

1.25 s 2 s

60 s 300 s

ESO

• dark current (acts like photon noise)• uncorrelated 1/ f noise• correlated 1/ f noise• alternating column noise (ACN)• picture-frame noise

Probably not important for background-limitedobservations; possibly for narrow-bandfilters/spectroscopy

Rauscher (2015)

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Outlook

• Framework for simulator exists

• First alpha release to consortium early 2016

• Two-phase development:

1. “ETC++”: concentrate on imaging/photometry and noise properties;produce “perfectly reduced images”; spectra extracted from cube

2. include instrumental effects, produce raw detector frames (science andcalibration), e.g. map spectra on focal-plane array

• Further questions:

Kieran Leschinskikieran.leschinski@univie.ac.at

Oliver Czoskeoliver.czoske@univie.ac.at

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Multi-conjugate Optics

Strehl mapsSCAO

MCAO

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