NICI The new Gemini South AO facility coronagraph by M. Hartung - - PowerPoint PPT Presentation

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NICI The new Gemini South AO facility coronagraph by M. Hartung - - PowerPoint PPT Presentation

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NICI The new Gemini South AO facility coronagraph by M. Hartung & T. Hayward, and E. Artigau, N. Zarate, G. Trancho, R. Galves, J. Luhrs, C. Urrutia, E. Christensen, M. Chun, D. Toomey, J. Jensen Background image courtesy: K. Davidson

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NICI – The new Gemini South AO facility coronagraph

by M. Hartung & T. Hayward,

and E. Artigau, N. Zarate, G. Trancho, R. Galves, J. Luhrs, C. Urrutia, E. Christensen, M. Chun, D. Toomey, J. Jensen Background image courtesy: K. Davidson

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Kyoto, May 2009 NICI – the GS AO facility coronagraph

Gemini international community Optimized for: Thermal IR High angular resolution Optimization choices: silver coating low emissivity (2.5% M1+M2) F/16 narrow field Thin spiders low diffraction LLT space planed behind M2 Cass: 3 instr.+Cal unit + AO system 90% Queue

Gemini: A specialized telescope

Slide courtesy F. Rigaut

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NICI: AO System + Lyot Coronagraph + Dual-channel Near-IR Camera

–

Optimized for high-contrast imaging

(no lenses, minimal static aberrations, differential imaging)

–

  • AO System: 85-element curvature system
  • natural guide stars
  • H-band Strehl ratio between 0.2 (V ~ 13) to ~ 0.4 (bright stars)

Science Camera: Dual-channel InSb (1-5 µm, only 1 – 2.5 offered) – Focal-plane and pupil masks – Beamsplitting elements, filters in each channel.

3/25/09 3 NICI Technical Assessment

NICI Overview

www.gemini.edu, see NICI

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Observing Modes

Angular Differential Imaging (ADI): Ideal PSF subtraction

  • Cass Rotator fixed, static pupil  stable speckle pattern

Spectral Differential Imaging (SDI)

  • Simultaneous dual-wavelength imaging
  • contrast gain for targets with CH4 absorption (T_eff < 1300 K)

NICI combines both techniques (ASDI)

  • Meanwhile 1 semester experience

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Planet-finding campaign (M. Liu et al.)

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Special DD programs on bright targets

3/25/09 4 NICI Technical Assessment

NICI Overview

www.gemini.edu, see NICI

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Kyoto, May 2009 NICI – the GS AO facility coronagraph

NICI for 2009B

  • 17 proposals for a total of 257 hours for 2009B.

Given oversubscription rates, up to 130 hours of awarded PI NICI time for 2009B

  • 120 hour commitment for NICI Campaign
  • Mostly used as summer instrument (good weather and seeing conditions)

NICI Campaign: ~190 observed already, close to 40% of full awarded Campaign time (500 h)

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Kyoto, May 2009 NICI – the GS AO facility coronagraph

Something to touch (from Chris Ftaclas' laboratory, Univ. Hawaii)

  • DM (bimorph), Hokupa'a 85 electrode pattern, as in NICI now
  • ground between the plates
  • curvature AO system: circular arrangement
  • front electrode (to apply a strong focus)
  • ~ 15 m radius (or ~30 fringes or stroke of 20 to 30 microns)

corresponding lenslet array

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Kyoto, May 2009 NICI – the GS AO facility coronagraph Chun et al., SPIE, 2008 http://www.gemini.edu/sciops/instruments/nici/itc-sensitivity-and-overheads

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Kyoto, May 2009 NICI – the GS AO facility coronagraph Chun et al., SPIE, 2008 http://www.gemini.edu/sciops/instruments/nici/itc-sensitivity-and-overheads

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Kyoto, May 2009 NICI – the GS AO facility coronagraph

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Kyoto, May 2009 NICI – the GS AO facility coronagraph

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Kyoto, May 2009 NICI – the GS AO facility coronagraph

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Kyoto, May 2009 NICI – the GS AO facility coronagraph

Bottom port

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Kyoto, May 2009 NICI – the GS AO facility coronagraph

Side port

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Kyoto, May 2009 NICI – the GS AO facility coronagraph

NICI PSF in H-Band NICI PSF in H-Band without coronagraphic mask

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Kyoto, May 2009 NICI – the GS AO facility coronagraph

2.3” x 2.3” FOV

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Kyoto, May 2009 NICI – the GS AO facility coronagraph

2.3” x 2.3” FOV

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Kyoto, May 2009 NICI – the GS AO facility coronagraph

2.3” x 2.3” FOV Linear stretch

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Kyoto, May 2009 NICI – the GS AO facility coronagraph

2.3” x 2.3” FOV PSF without cow PSF with cow Log stretch ...

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Kyoto, May 2009 NICI – the GS AO facility coronagraph Thick spider arm (30 x the imaged M2 support arm)

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Kyoto, May 2009 NICI – the GS AO facility coronagraph

2.3” x 2.3” FOV

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Kyoto, May 2009 NICI – the GS AO facility coronagraph

2.3” x 2.3” FOV

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Kyoto, May 2009 NICI – the GS AO facility coronagraph

2.3” x 2.3” FOV

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Kyoto, May 2009 NICI – the GS AO facility coronagraph

2.3” x 2.3” FOV

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Kyoto, May 2009 NICI – the GS AO facility coronagraph

2.3” x 2.3” FOV

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Kyoto, May 2009 NICI – the GS AO facility coronagraph

2.3” x 2.3” FOV

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Kyoto, May 2009 NICI – the GS AO facility coronagraph

2.3” x 2.3” FOV

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Kyoto, May 2009 NICI – the GS AO facility coronagraph

2.3” x 2.3” FOV

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Kyoto, May 2009 NICI – the GS AO facility coronagraph

2.3” x 2.3” FOV

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Kyoto, May 2009 NICI – the GS AO facility coronagraph

ADI reduction

(Angular Differential Imaging – Cassegrain rotator fixed, pupil fixed =>

  • ptimal PSF subtraction)

For the red arm, for the blue arm separately:

  • dark, flat, bad pixel corr
  • Register (subpixel shift) to central star (below the occulting mask, if not

saturated, spot can be used for centering, Strehl, and flux esitation!)

  • Highpass (looking for point sources!)
  • match speckles (e.g. simplex minimization), scale intensity
  • median ADI cube to get PSF frame (potential companions cancel out if

enough field rotation)

  • subtract PSF frame from cube (matching speckles of individual frames)

SDI reduction (Simultaneous or Spectral Differential Imaging - cancel primary, keep cool methane containing object)

  • shift, adjust image scale according to filter wavelength of red and blue

channel

  • subtract final results of both arms
  • Lit. ADI/SDI e.g. from GDPS, authors e.g. Marois, Lafreniere, Artigau, Biller, etc.
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Kyoto, May 2009 NICI – the GS AO facility coronagraph

0.3” 1”

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Kyoto, May 2009 NICI – the GS AO facility coronagraph

1” 0.3”

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Kyoto, May 2009 NICI – the GS AO facility coronagraph

0.3” 1”

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Kyoto, May 2009 NICI – the GS AO facility coronagraph Artigeau et al., SPIE, 2008

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Kyoto, May 2009 NICI – the GS AO facility coronagraph Artigeau et al., SPIE, 2008

Contrast Gain applying SDI (on top of ADI)

SDI most effective inside 1”. Efficiency for ADI increases for larger radii.

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Kyoto, May 2009 NICI – the GS AO facility coronagraph

LOCI

Locally Optimized Combination of Images OT Region of image for which reference PSF is reconstructed Ok Same Region of kth reference image i Pixel index of this region

Artigeau et al., SPIE, 2008 Lafreniere, Marois, Doyon, Nadeau, Artigau, A&A, 2007

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Kyoto, May 2009 NICI – the GS AO facility coronagraph Lafreniere, Marois, Doyon, Nadeau, Artigau, A&A, 2007

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Kyoto, May 2009 NICI – the GS AO facility coronagraph

NICI Pipeline release

  • Pyraf (but using python only for NICI)
  • Beta release July 2009, Nelson Zarate
  • Update February 2010, Nelson Zarate

www.gemini.edu , see DATA, Gemini IRAF package Pipeline will output many intermediate products (standard reduction, ADI, SDI, ASDI, LOCI, etc.)

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Kyoto, May 2009 NICI – the GS AO facility coronagraph

Summary

  • Contrast up to dH = 13.5 @ 0.5” (90 min) “bad house number”
  • Verify pipelines (fake planets, simulations, photometry)
  • Do it yourself, pipeline releases no grant for being science proof
  • Solid understanding of PSF and its artifacts needed
  • And ...
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Kyoto, May 2009 NICI – the GS AO facility coronagraph

Summary

  • Contrast up to dH = 13.5 @ 0.5” (90 min) “bad house number”
  • Verify pipelines (fake planets, simulations, photometry)
  • Do it yourself, pipeline releases no grant for being science proof
  • Solid understanding of PSF and its artifacts needed
  • And check your telescope for a cow