1. Prospects – JWST, EUCLID, WFIRST Jeff Kruk (GSFC) Jeffrey.Kruk@nasa.gov

2. Outline HST: now to 2015 and beyond… JWST: 2015 - 2025 EUCLID(?): 2018-2023 WFIRST: XX - XX+5… 11/15/20102J. Kruk STScI Slitless Spectroscopy wkshp

3. Sky backgrounds 11/15/2010J. Kruk STScI Slitless Spectroscopy wkshp3

4. HST slitless modes InstrumentFoV (arcmin) PlatescaleRBandpass (nm) ACS WFC grism 3.4’x3.4’0.05”100550-1050 ACS SBC prisms 0.58’x0.51’0.025”79 96 115-180 125-180 WFC3 NIR grisms 2.05’x2.27’0.13”210 130 800-1150 1075-1700 WFC3 UVIS grism 2.7’x2.7’0.04”70200-400 NIC3 prisms0.87’x0.87’0.203”2000.8-1.2 1.1-1.9 1.4-2.5 STIS NUV prism 0.42’x0.42’0.024”2500-10115-350 11/15/20104J. Kruk STScI Slitless Spectroscopy wkshp

5. JWST slitless modes InstrumentFoV (arcmin) PlatescaleRBandpass (nm) NIRCAM 2 grisms, Rotated 90° 2.16’x2.16’0.0648”20002400-5000 (filters in series) NIRSpec* prism, gratings 3.4’x3.6’0.1”100 1000, 2700 700-5000 *NIRSpec micro-shutters: 0.2”x0.45” - open area ratio is 0.7 if all left open 11/15/20105J. Kruk STScI Slitless Spectroscopy wkshp

6. EUCLID NIR slitless spectroscopy Launch in 2018 if selected, 5 year mission duration Survey 20000 deg 2 – limiting line flux 4*10 -16 ergs/cm 2 /s Characteristics (Laureijs et al 2010 SPIE 7731): – 1.2m primary, 0.35m secondary obscuration – 4 grisms in wheel, identical except for 90° rotations – 1.0-2.0 microns – R=500 – Focal plane: (choice still TBD?) 12 SCAs: 0.33”/pix 36.4’x48.5’ (0.49 sq deg) 16 SCAs: 0.31”/pix 46.1’x46.1’ (0.59 sq deg) 11/15/20106J. Kruk STScI Slitless Spectroscopy wkshp

7. WFIRST Launch: ?? - depends on JWST schedule Mission duration: 5 years min, 10 years goal Objectives: – 10000 deg 2 WL survey (30 gal/sq arcmin) – 20000 deg 2 BAO survey (limiting flux 1.6 10 -16 ) – 150 SNIa per  z=0.1 – (didn’t quite fit into 5 years, but close) EOS panel recommendations cuts time in ~half for first 5 years of mission 11/15/20107J. Kruk STScI Slitless Spectroscopy wkshp

8. WFIRST characteristics (details subject to change!) Imager – 0.4-2.0  m – 0.18”/pixel – 4x6 array of SCAs (0.25 deg 2 ) – Filter wheel: 5 filters, R=75 prism, blank Spectrometers (2, w/ opposing dispersions) – 1.1-2.0  m – 0.37”/pixel – 2x3 array of SCAs (0.26 deg 2 ) each – R=270-327 per 2 pixels R  = 200-240”, or c/R  = 1500-1250km/s/arcsec 11/15/20108J. Kruk STScI Slitless Spectroscopy wkshp

9. WFIRST block diagram (details almost certain to change) 11/15/20109J. Kruk STScI Slitless Spectroscopy wkshp

10. WFIRST focal planes as projected onto the sky 11/15/201010J. Kruk STScI Slitless Spectroscopy wkshp

11. Design Trades grism vs. prism Grism pros: – zero-order gives wavelength reference – Allows higher dispersion Grism cons: – Zero order increases spectral contamination – Higher dispersion not needed for BAO; if lines resolved, S/N is reduced – Higher orders contaminate spectra – 1 st order throughput lower than prism 11/15/201011J. Kruk STScI Slitless Spectroscopy wkshp Grism simulation courtesy of David Larson

12. Design Trades Dispersion – σ z /(1+z) < 0.001, resolve O III, don’t resolve Hα Bandpass – Redshift coverage & spectral diagnostics vs zodiacal light – Combined w/dispersion -> length of spectral trace Number of roll angles, size of roll offset – 4 rolls: 0°,5°; 170°,175° found sufficient Don’t set 2 spectrometers exactly 180° apart 11/15/2010J. Kruk STScI Slitless Spectroscopy wkshp12

13. Imager sim – 225 sec 11/15/2010J. Kruk STScI Slitless Spectroscopy wkshp13 Imager simulation – 225sec 1SCA (log stretch) Courtesy David Larson

14. 11/15/2010J. Kruk STScI Slitless Spectroscopy wkshp14 Spectrometer simulation – 225 sec 1SCA (log stretch) Courtesy David Larson

15. 4° roll offset 11/15/2010J. Kruk STScI Slitless Spectroscopy wkshp15 Roll = 0Roll = 4

16. 11/15/2010J. Kruk STScI Slitless Spectroscopy wkshp16 133 ksec deep exp (SN field) asinh stretch Galaxies & stars only - no background Courtesy David Larson

17. General issues EUCLID, WFIRST not as clean as HST – PSF, pixels are large compared to HST – Pointing stability, dithering, less precise than HST What dithering is desirable/required in this context? Direct images are obtained with a different instrument at different times – Use edges of traces of bright stars in field for registration 11/15/2010J. Kruk STScI Slitless Spectroscopy wkshp17

18. Issues continued: calibrations BAO needs accurate wavelengths Optical distortion calibration is critical – not challenging SNIa needs accurate fluxes If from spectra, flat-field cube is critical – challenging Would like to derive flat-field internally from the data – Has been done for imaging instruments (Arendt et al. 2010 ApJS 186 10) – Dimensionality of problem is higher for slitless spectrometer; will need extensive simulations to test Persistence corrections Can pipeline maintain continuous exposure history? Initial planning limited to DE programs – Need to reevaluate for larger WFIRST program 11/15/2010J. Kruk STScI Slitless Spectroscopy wkshp18

19. Issues cont. Datasets are large! – Manual processing not practical for 10 9 galaxies Extract ~10 9 to obtain 10 8 emission-line galaxies – “…it is still mandatory to check and validate the products before any science investigation can commence. ” (The WFC3 IR Grism Data Reduction Cookbook – Extracting several 100 grism spectra made easy) 11/15/2010J. Kruk STScI Slitless Spectroscopy wkshp19

20. Issues cont. Datasets are large! – Manual processing not practical for 10 9 galaxies Extract ~10 9 to obtain 10 8 emission-line galaxies – “…it is still mandatory to check and validate the products before any science investigation can commence. ” (The WFC3 IR Grism Data Reduction Cookbook – Extracting several 100 grism spectra made easy) Uh Oh….. Crowd-sourcing? Doesn’t look like as much fun as the Galaxy zoo 11/15/2010J. Kruk STScI Slitless Spectroscopy wkshp20

21. WFIRST - what’s next? Astro-2010 provided fairly strict guidance, – But details left open for further optimization The science goals have expanded to fill a 10- year mission. – While plausible, the nominal design life is 5 years (so everyone starts out unhappy) The Science Definition Team may have a big role in defining the details. Stay tuned. 11/15/201021J. Kruk STScI Slitless Spectroscopy wkshp

22. WFIRST telescope trade: 1.5m on-axis vs 1.3m off-axis 11/15/201022J. Kruk STScI Slitless Spectroscopy wkshp PSF - scaled by effective area Encircled Energy Diffraction from spider arms not included

23. EOS observing plan BAO+WL: <~2 years Sne: 0.5 years Micro-lensing (Galactic bulge): 1.4 years Galactic plane survey: 0.5 year Guest-observer surveys: 1 year – This means you! 11/15/2010J. Kruk STScI Slitless Spectroscopy wkshp23

24. WFIRST SDT Deadline for applications to the WFIRST Science Definition Team: Nov 23 rd, 2010 Please Apply! Further info: http://wfirst.gsfc.nasa.gov 11/15/2010J. Kruk STScI Slitless Spectroscopy wkshp24