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Wide-Field Slitless Spectr scopy with NIRISS

JWST FGS. Wide-Field Slitless Spectr scopy with NIRISS. Van Dixon STScI. TIPS/JIM 2012 September 20. NIRISS at a Glance. Dual-Wheel Configuration. GR150R. GR150C. Dual-Wheel Configuration. GR150R. GR150C. GR150C. GR150R. Blaze Function for GR150 Grisms.

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Wide-Field Slitless Spectr scopy with NIRISS

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  1. JWST FGS Wide-Field Slitless Spectrscopy with NIRISS Van Dixon STScI TIPS/JIM 2012 September 20

  2. NIRISS at a Glance

  3. Dual-Wheel Configuration GR150R GR150C

  4. Dual-Wheel Configuration GR150R GR150C GR150C GR150R

  5. Blaze Function for GR150 Grisms

  6. First-Order Sensitivity: Emission Lines Minimum line flux to reach S/N = 10 in 10 ks

  7. First-Order Sensitivity: Emission Lines z = 9 z = 17 Redshifted Lyman α

  8. The Software • The aXe software package was developed to support slitless spectroscopy with ACS and WFC3 (Kümmel et al. 2009). aXeSIMgenerates synthetic direct and dispersed images of the sky. aXeextracts and calibrates spectra. aXedrizzle allows for the combination of dithered images. aXe2web displays the extracted spectra in a convenient HTML format. aXe was originally developed by the Space Telescope - European Coordinating Facility (ST-ECF). The code is now supported by STScI. • Source Extractor builds a catalog of objects from an astronomical image (Bertin & Arnouts 1996).

  9. Input for aXeSIM • Configuration file • Location, trace, and dispersion of each spectral order • Sensitivity (including grating) • e-per erg/cm2 • Throughput (w/out grating; used to make direct image) • Flat Field (may be wavelength-dependent) • Master Sky Background Image • Input Catalog (output from Source Extractor) • Specify image size and shape or point to image file • Postage-stamp images • Spectra

  10. Location of Each Order (F150W) 2040 pixels Direct Image -1 0 +1 +2 +3 -601 -512 -227 0 53 148 336 520 619 893 1.03 1.3 1.7 (μm)

  11. Model Object Table # 1 NUMBER Object number # 2 X_IMAGE X coordinate (pixels) # 3 Y_IMAGE Y coordinate (pixels) # 4 A_IMAGE Length of semi-major axis (pixels) # 5 B_IMAGE Length of semi-minor axis (pixels) # 6 THETA_IMAGE Angle of major axis # 7 MAG_F1537 Magnitude at 1537 nm (WFC3 F160W) # 8 SPECTEMP Key to spectral template # 9 Z Redshift # 10 MODIMAGE Key to model image 1 900.00 1500.00 0.6 0.6 0.0 22.5 0 0.0 0 2 900.00 1250.00 30.0 10.0 45.0 18.0 0 0.0 0 3 900.00 1000.00 18.0 10.0 -30.0 18.0 1 0.0 1 4 900.00 750.00 5.0 2.0 60.0 18.0 2 0.0 0 5 900.00 700.00 5.0 2.0 60.0 18.0 2 0.075 0 6 900.00 650.00 5.0 2.0 60.0 18.0 2 0.15 0 7 900.00 600.00 5.0 2.0 60.0 18.0 2 0.22 0 x y a b θ mag sp z image

  12. Dispersed Image (log stretch) -1 0 +1 +2 +3 2040 pixels

  13. Millennium Run Observatory Semi-analytic galaxy-formation models based on the Millennium Run dark-matter simulations H-band image using the WFC3/F160W bandpass Overzier et al. 2012 (MNRAS, in press)

  14. Direct Image w/ NIRISS PSF

  15. Direct Image w/ Background (100 s)

  16. Source Extractor Apertures

  17. Dispersed Image: Horizontal

  18. Dispersed Image: Vertical

  19. aXe2web

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