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Introducing JWST’s NIRISS : The N ear I nfra R ed I mager & S litless S pectrograph

JWST FGS. Introducing JWST’s NIRISS : The N ear I nfra R ed I mager & S litless S pectrograph. Alex Fullerton STScI / HIA. TIPS/JIM 2011 September 15. The Tunable Filter Imager (TFI). TFI Lessons Learned. July 20, 2011: Wave good-bye to TFI. Say hello to NIRISS.

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Introducing JWST’s NIRISS : The N ear I nfra R ed I mager & S litless S pectrograph

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  1. JWST FGS Introducing JWST’s NIRISS:The Near InfraRedImager & SlitlessSpectrograph Alex Fullerton STScI / HIA TIPS/JIM 2011 September 15

  2. The Tunable Filter Imager (TFI)

  3. TFI Lessons Learned July 20, 2011: Wave good-bye to TFI. Say hello to NIRISS. Near InfraRed Imager & SlitlessSpectrograph #1: Cryogenic etalons are tricky.

  4. Design Considerations for NIRISS Emphasis of nascent GTO Programs “Scope” is the only adjustable parameter available to CSA Program Management. Helps the S&OC (i.e., us) a bit. • Maintain capability to address core TFI Science • “First Light” • Exoplanets • Minimize technical risk • Schedule is a (big) issue • Cost is a (big) issue • Simplify operations

  5. Observing Modes

  6. Optical Layout of the TFI 20482048 HgCdTe 5.2 micron cut-off 18 micron pixels

  7. Optical Layout of NIRISS 20482048 HgCdTe 5.2 micron cut-off 18 micron pixels

  8. Elements in the NIRISS Dual Wheel

  9. Wide-Field Slitless Spectroscopy

  10. Slitless Spectroscopy with Two Orthogonal Grisms • A spectrum for every source in the field of view.

  11. NIRISSisCompetitiveWithNIRSpec Bad Good

  12. Sparse-Aperture Interferometric Imaging

  13. Sparse-aperture interferometry with NIRISS pushes the angular resolution of JWST to its limit Bright planets Faintplanets goal Beichman et al 2010

  14. Filter Set (3) for Use WithMASKNR • Optimized for constraining temperature and mass.

  15. Single-Object Slitless Spectroscopy

  16. G700XD design Slitless cross-dispersed 0.6-3.0 μm spectroscopy • R∼700 dispersion with grism along V2 • Low dispersion with prism along V3, to separate orders • Weak cylindrical lens on front side of prism to induce a defocus along V3 weak cylindrical surface m=3 m=2 m=1 m=0

  17. Schematic of Transit and Eclipse Science Seager & Deming (2010, ARAA, 48, 631) Eclipse Planet thermal emissionappears and disappears 10-3 Transit Learn about atmospheric circulation from thermal phase curves Measure size of planet 10-2 See starlight transmitted through planet atmosphere 10-4

  18. Transit Spectrum of Habitable “Ocean Planet” NIRISS G700XD perfectly suited for such challenging programs. The water vaporfeaturesbelow have a depth of 50 parts per million. NIRISS wavelength range 2.5 μm 0.6 μm

  19. Broad-Band Imaging - Blue

  20. Broad-Band Imaging - Red

  21. NIRISSSensitivityvs NIRCam NIRISS with spare NIRCam filter filter Good In general , NIRISS is more sensitive thanNIRCam.

  22. Summary NIRISS is coming! Capable instrument Complements & Extendsnear-IRcapability ofJWST Straightforward to operate* First Light: Lyman alpha emitters (10< z<13) ; photometric redshifts High-resolution imaging: exoplanet imaging and characterization Spectroscopy of transiting exoplanet atmospheres (including H2O, CO2features…) * Grisms / aperture mask introduce complexity on the “back end”.

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