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James Webb Space Telescope: The Near-Infrared Imager and Slitless Spectrograph (NIRISS)
Pupil Wheel
F140M [7] F158M [8] F115W [9] Active Element GR150C [9]

Filter Wheel
Detector
F277W [8] F444W [7]

At a glance:
Teledyne HAWAII-2RG; HgCdTe with 5.2m cutoff; 2048 в 2048 pixels 2.2ґ в 2.2ґ 0.065 arcsec / pixel "Blue" filters; Grism GR700XD; Aperture Mask NRM "Red" filters; Grisms GR150C,R

F150W [6] F090W [1] F200W [5] [2] NRM [4]
CLEARP

F356W [6] GR150R [1] F430M [5] CLEAR [2] F480M [3] F380M [4]

Field of View Plate scale Pupil Wheel Filter Wheel

GR700XD [3]

Obser ving Modes
Imaging Point-Source Sensitivity: S/N=10 in 10 ks Aperture Masking Interferometry NRM + Medium-Band "Red" Filters 7-hole aperture mask with 21 distinct ("non-redundant") separations ("baselines") Michelson: = 0.5 / D Single-Object Slitless Spectroscopy GR700XD grism + CLE AR
· Two cross-dispersed orders · Spectral coverage 0.6 ­ 2.8 m · Resolving Power 1st order: 700 @ 1.25 µm 2nd order: 700 @ 0.63 µm The orders are broadened in the cross-dispersion direction by 20 ­25 pixels. Subarray readout formats optimize SOS S for timeresolved spectroscopy of transiting exoplanets. Estimated bright limits (G2 V star): Subarray J mag 25 6 x 2 0 4 8 8. 2 8 0 x 20 4 8 6.9

Filter
F090W F115W F150W F200W F277 W F356W F444W

nJ y
20.0 17.5 14.3 11.9 14.5 12.6 25.1 M a sk

Inter ferogram

Estimated "End of Life" values

NIRISS AMI enables exoplanet detection at 3.8, 4.3, and 4.8 m around stars as bright as M'~4, reaching 10-4 contrast at separations of 70 ­ 4 0 0 milli-arcseconds. It provides lower contrast at 2.8 m with the F277 W filter. Image reconstruction is also enabled.

Fourier Transform

"R"

Wide-Field Slitless Spectroscopy

"C"

GR150{C,R} grisms + "Blue" Filters · Resolving Power (1st order): ~150 · Spectral coverage (1st order): 0.8 ­ 2.2 m · Blocking filters isolate wavelengths of interest. · {Column, Row} orientations provide orthogonal dispersion directions on the detector to mitigate blending. Fiducial sensitivity (unresolved line): 5 в10-18 erg/s/cm2 with S/N=10 in 10 ks


Filter Transmission Profiles

Wide-Field Slitless Spectroscopy with NIRISS: Simulations of MACS J0647+7015

Image: F200W

Layout of Npectral Orders ( Wide-Field Slitless Spectroscopy) S IRISS%WFSS:%Geometry%of%Orders%
-2
F090W% F115W% F140M% F150W% F158M% F200W% 0%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%500%%%%%%%%%%%%%%%%%%%%%%%%%%%1000%%%%%%%%%%%%%%%%%%%%%%%%%1500%%%%%%%%%%%%%%%%%%%%%%%%%%2000% 0 500 1000 1500 2000 Note:%Direct%image%falls%at%1.05%m.%

0 2 0%%%%%%%%%%%%%1%%%%%%%%%%%%%2%%%%%%%%%%%%%%3%

First=Order%Wavelength%(m)%

4

6

Spectra: GR150R, F200W

Single-Object Slitless Spectroscopy with NIRISS
0 Transmission Spectrum (ppm)

Transit Depth = 24376 ppm

-500

Spectra: GR150C, F200W

Simulated NIRISS/SOSS spectrum of the atmosphere of WASP 43b. Model courtesy of J. Fortney.

-1000

-1500

-2000

Model Order 1 Order 2 Saturated
1000

http://www.stsci.edu/jwst /instruments/niriss
JMAG = 10.00 NREAD = 11 SUB-ARRAY = 256x2048 Elapsed Clock Time = 2.4 h

1500 2000 Wavelength (nanometers)

2500

Operated for NASA by AURA

AC SP E TELESCOPE SCIENCE INSTITUTE

Simulated SOSS spectrum of HD 189733b