Transcript Introducing JWST’s NIRISS: The Near InfraRed Imager & Slitless Spectrograph Alex Fullerton

Introducing JWST’s NIRISS:
The Near InfraRed Imager & Slitless Spectrograph
Alex Fullerton
STScI / HIA
TIPS/JIM
2011 September 15
The Tunable Filter Imager (TFI)
TIPS / JIM
Presenter
Title
2004 May 20
Nelan
JWST FGS SRR (April 7, 2004)
2005 March
17
Fullerton
Overview of Calibration Activities for the JWST
FGS-TFI
2005 May 19
Fullerton
FGS Tunable Filter Imager: Updates from PDR
2006 June 15
Fullerton
“Phase C” Design of the JWST/FGS Tunable Filter
Imager
2008 Sept. 18
Fullerton
The Tunable Filter Imager Passes its CDR[s]
2010 Sept. 16
Sivaramakrishnan The Non-Redundant Mask on JWST
2010 Nov. 18
Sivaramakrishnan
2011 March 17 Chayer
TIPS/JIM
2011 September 15
Non-Redundant Tilts (NRT): A Fallback Coarse
Phasing Method for JWST Using TFI
JWST FGS & TFI Cryovac Risk Mitigation Tests
TFI Lessons Learned
#1: Cryogenic etalons are tricky.
July 20, 2011:
Wave good-bye to TFI.
Say hello to NIRISS.
Near InfraRed Imager & Slitless Spectrograph
TIPS/JIM
2011 September 15
Design Considerations for NIRISS
 Maintain capability to address core TFI Science
• “First Light”
• Exoplanets
Emphasis of nascent GTO Programs
 Minimize technical risk
• Schedule is a (big) issue
• Cost is a (big) issue
 Simplify operations
TIPS/JIM
2011 September 15
“Scope” is the only adjustable parameter
available to CSA Program Management.
Helps the S&OC (i.e., us) a bit.
Observing Modes
TFI
Narrow-Band Imaging
R~100; tunable 1.5 – 2.6 & 3.0 – 5.0 microns
Coronagraphic Imaging
R~100; tunable 3.0 – 5.0 microns
Sparse-Aperture Interferometric Imaging
R~100; tunable 3.0 – 5.0 microns
NIRISS
Wide-Field Slitless Spectroscopy
R~ 150; 1.0 – 2.5 microns
XXXXXXXXXXXXXXXXX
Sparse-Aperture Interferometric Imaging
Fixed medium-band filters
Single-Object Slitless Spectroscopy
R~700; 0.7 – 3.0 microns
Broad-Band Imaging
Fixed filters; 1 – 5 microns
TIPS/JIM
2011 September 15
Optical Layout of the TFI
20482048 HgCdTe
5.2 micron cut-off
18 micron pixels
TIPS/JIM
2011 September 15
Optical Layout of NIRISS
20482048 HgCdTe
5.2 micron cut-off
18 micron pixels
TIPS/JIM
2011 September 15
Elements in the NIRISS Dual Wheel
TIPS/JIM
2011 September 15
Wide-Field Slitless Spectroscopy
TIPS/JIM
2011 September 15
Slitless Spectroscopy with Two Orthogonal Grisms
• A spectrum for every source in the field of view.
NIRISS is Competitive With NIRSpec
Bad
Good
Sparse-Aperture Interferometric Imaging
TIPS/JIM
2011 September 15
Sparse-aperture interferometry with NIRISS pushes the
angular resolution of JWST to its limit
Bright planets
goal
Faint planets
Beichman et al 2010
Filter Set (3) for Use With MASKNR

Optimized for constraining temperature and mass.
Single-Object Slitless Spectroscopy
TIPS/JIM
2011 September 15
G700XD design
Slitless cross-dispersed 0.6-3.0 μm spectroscopy
weak
cylindrical
surface
m=3
m=2



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
m=1
m=0
Schematic of Transit and Eclipse Science
Seager & Deming (2010, ARAA, 48, 631)
Transit
Measure size of planet 10-2
See starlight transmitted
through planet atmosphere 10-4
Eclipse
Learn about atmospheric
Planet thermal
circulation from thermal
emission appears
phase curves
and disappears 10-3
17
Transit Spectrum of Habitable “Ocean Planet”
NIRISS G700XD perfectly suited for such challenging programs.
The water vapor features below have a depth of 50 parts per million.
NIRISS wavelength range
0.6 μm
2.5 μm
Broad-Band Imaging - Blue
TIPS/JIM
2011 September 15
Broad-Band Imaging - Red
TIPS/JIM
2011 September 15
NIRISS Sensitivity vs NIRCam
NIRISS with spare NIRCam filter filter
Good
In general , NIRISS is more sensitive than NIRCam.
Summary
NIRISS is coming!
Capable instrument
Complements & Extends near-IR capability of JWST
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, CO2 features…)
* Grisms / aperture mask introduce complexity on the “back end”.
TIPS/JIM
2011 September 15