1. INS NIRSpec, 12 May 2005 Introduction to NIRSpec Michael Regan

2. JWST Project Organigramme June 2004 JWST Project Manager P. Jensen NIRSpec Pr. System Engineer G. Bagnasco Launcher System Engineer P. Rumler System Group MIRI Principal System Engineer A. Marini Admin. Assistant A. Plitzke Documentation & Conf. Control D. Green Mech. Thermal System Engineer J-C. Salvignol Project Control Manager Z. El Hamel PA Manager J. van Dooren Subsystem Expert Group Optical System Engineer M. Te Plate Electr. System Engineer & AIV P. Rumler Ops, SW & Detector System P. Strada Mechanism Engineer* B. Henson * leaving Schedule Control J. Molleman Project Scientist P. Jakobsen Deputy Project Scientist T. Boeker Science Operations Team NN Science Support NN Contracts Officer V. D’Hoedt Optical Support P. Marenaci (YGT)

3. INS NIRSpec, 12 May 2005 JWST Architecture Optical Telescope Element (OTE) Integrated Science Instrument Module (ISIM) Element Spacecraft Bus Sunshield Sun

4. INS NIRSpec, 12 May 2005 Telescope

5. INS NIRSpec, 12 May 2005 Telescope

6. INS NIRSpec, 12 May 2005 Funky PSF? Image Core PSF Wings 2 µm

7. INS NIRSpec, 12 May 2005 ISIM & Regions

8. INS NIRSpec, 12 May 2005 Thus Spoke ASWG

9. INS NIRSpec, 12 May 2005 Current Mission Requirements (the TAC will decide anyway…)

10. INS NIRSpec, 12 May 2005 NIRSpec

11. INS NIRSpec, 12 May 2005 NIRSpec: A Pretty Picture is Not Enough Enter NIRSpec

12. INS NIRSpec, 12 May 2005 NIRSpec: Thus Spoke ASWG 3 x 3 arcmin FOV 1-5 µm coverage R~1000, R~100 multiplexed >100 sources simultaneously Configurable slit width/length MEMS array preferred

13. INS NIRSpec, 12 May 2005 NIRSpec Procurement Instrument built by European industry under ESA project leadership Under study since 2001 Presently entering implementation phase Two NASA-provided components: 2 x 2k x 2k HgCdTe Detector Array 4 x 384 x 185 Micro-Shutter Array

14. INS NIRSpec, 12 May 2005 NIRSpec Modes R=100 (exploratory spectroscopy) Single prism 0.6 - 5.0 µm Micro-shutter array or fixed Slits R=1000 (emission line diagnostics) 3 gratings 1.0 - 5.0 µm Micro-shutter array or fixed slit(s) R=3000 (emission line kinematics) 3 gratings 1.0 - 5.0 µm Fixed slit or integral field unit

15. INS NIRSpec, 12 May 2005 Wavelength Coverage R=1000 & R=3000 modes 1.0 - 5.0 µm Covered by three overlapping first order gratings: 1.0 - 1.8 µm 1.7 - 3.0 µm 2.9 - 5.0 µm R=100 mode 0.6 - 5.0 µm (as NIRCAM) Covered by single dual-pass prism Coverage below 1.0 µm is not allowed to drive anything Resolution to be kept within factor 2 of R=100 1.0 - 5.0 µm Resolution below 1.0 µm to follow

16. INS NIRSpec, 12 May 2005 You Can’t Fight Red shift ! NIRMIR !

17. INS NIRSpec, 12 May 2005 Micro Shutter Array 4 x 384 x 185 Shutters 9 Square Arcmin of MSA Area Single 200 mas x 450 mas slits surrounded by 60 mas wide bars >100 objects simultaneously IFU

18. INS NIRSpec, 12 May 2005 A Bit of MEMS History Initially both Micro Mirrors and Shutters Mirrors eliminated due to excessive diffraction effects Initially slit to be made up of several shutters Later transitioned to “fat MEMS” Huge simplification of optics Factor ~4 reduction in MSA array Reduced slit loss At expense of multiplexing loss

19. INS NIRSpec, 12 May 2005 Diffraction & Slit Loss Telescope Exit Pupil Spectrograph Entrance Pupil Footprint of PSF Diffracted Output Beam

20. INS NIRSpec, 12 May 2005 MSA Close-up Key Requirements: Contrast: >2000 (!) Open Fill factor >70% (60 mas bars on 200 mas wide slits)

21. INS NIRSpec, 12 May 2005 MSA Magnet Mechanism

22. INS NIRSpec, 12 May 2005 MSA in Action

23. INS NIRSpec, 12 May 2005 MSA Contrast Simulation HDF-S Field Select Objects (Detail)

24. INS NIRSpec, 12 May 2005 MSA Contrast Simulation Undispersed image with MSA mask in place Spoilers! Configure Slits (Detail)

25. INS NIRSpec, 12 May 2005 MSA Contrast Simulation Configure Slits (larger view) Image Mode with MEMS mask in place

26. INS NIRSpec, 12 May 2005 MSA Contrast Simulation Insert Grating and Integrate

27. INS NIRSpec, 12 May 2005 Integral Field Unit

28. INS NIRSpec, 12 May 2005 Integral Field Unit FOV: 3” x 3” Sampling: 0.1” ~30 Slicers Entirely passive device (no moving parts) Shuttered by MSA magnet mechanism Main use R~3000 single object But R~1000 and R~100 too.... Superb backup in case of MSA failure Point and shoot operations

29. INS NIRSpec, 12 May 2005 Integral Field Unit Slicer Stack (30 slices) IFU aperturePupil mirror Line (30 elements) Slit mirror Line (30 elements) Relay optics

30. INS NIRSpec, 12 May 2005 Detector Array 2K  4K FPA comprised of two 2K  2K sensor chip assemblies (SCAs) =0.6–5.0 µm HgCdTe detectors (Rockwell) FPA passively cooled to T=34–37 K Key Performance Parameters: Total noise =6 electrons rms per t=1000 seconds exposure) QE = >80% NIRSpec is detector background limited in nearly all modes (!) Non-stop (“up the ramp”) read and telemetry 12 s frame time, 1 frame downlink each 50 s

31. INS NIRSpec, 12 May 2005 Why R=1000?

32. INS NIRSpec, 12 May 2005 Why R=1000? Science requirement Clean emission line separation Main challenge: [NII] 6548.1 :1 H  6562.8 metallicity diagnostic [NII] 6583.4 :3 and also: [SII] 6716.4 density diagnostic [SII] 6730.8 R=446 R=319 R=467 [NII] HH

33. INS NIRSpec, 12 May 2005 Why 200 mas Slit? 1:2 MSA aspect ratio fixed 1.4 µm - Band I 2.4 µm - Band II 4.0 µm - Band III

34. INS NIRSpec, 12 May 2005 Why 200 mas Slit? 200 mas optimal? 2 pixels across slit

35. INS NIRSpec, 12 May 2005 Optical Schematic 200 mas per 79.5 µm wide shutter 2.52 “/mm, f/12.5 100 mas per 18 µm pixel 5.56 “/mm, f/5.67 1.58 “/mm, f/20

36. INS NIRSpec, 12 May 2005 Optical Layout Buzzwords: TMA’s Scheimflug

37. INS NIRSpec, 12 May 2005 Focal Plane Layout & Scheimflug NIRCam NIRSpec

38. INS NIRSpec, 12 May 2005 Physical Layout

39. INS NIRSpec, 12 May 2005 Physical Layout

40. INS NIRSpec, 12 May 2005 SiC The wonder of modern ceramics

41. INS NIRSpec, 12 May 2005 WFE at MSA Requirement: Diffraction-limited at 2.4 µm WFE = 180 nm rms or better 131 nm rms OTE input specified Fore optics challenging Relaxation requires degrading sensitivity Increased slit losses Reduced photometric accuracy

42. INS NIRSpec, 12 May 2005 WFE at FPA Requirement: Diffraction-limited at 3.0 µm WFE = 225 nm rms or better Camera optics challenging Relaxation requires degrading sensitivity Larger resolution element Decreased sensitivity Jeopardize spectral resolution [NII] HH

43. INS NIRSpec, 12 May 2005 NIRSpec Image Quality PSF at MSA PSF at FPA FPA 100 mas pixels PSF at MSA FPA with Cross-talk

44. INS NIRSpec, 12 May 2005 Grating Wheel 8 Positions: 1. R=100 Prism 2. Band I R=1000 Grating 3. Band II R=1000 Grating 4. Band III R=1000 Grating 5. Band I R=3000 Grating 6. Band II R=3000 Grating 7. Band III R=3000 Grating 8. Provision for imaging mode

45. INS NIRSpec, 12 May 2005 Filter Wheel 8 Positions: 1. Clear Aperture 2. Closed 3. Band I Long Pass  >1.0 µm 4. Band II Long Pass  >1.7 µm 5. Band III Long Pass  >2.9 µm 6. Narrow Band TA  =1.1 µm 7. Broad Band TA 0.9 <  1.1 µm 8. Broad Prism 0.9 <  5 µm Current Issue: Filters in pupil – should they second as pupil stops?

46. INS NIRSpec, 12 May 2005 Why Long Pass? One Object per Row

47. INS NIRSpec, 12 May 2005 Calibration Unit Carries both continuum and (FP-filtered) line sources

48. INS NIRSpec, 12 May 2005 NIRSpec Sensitivity Formal Level I Specs

49. INS NIRSpec, 12 May 2005 Mission Requirements

50. INS NIRSpec, 12 May 2005 Mission Requirements

51. INS NIRSpec, 12 May 2005 Target Acquisition Partially documented in gory detail… NIRSpec Operations Concept Two dedicated tech notes (more to come) Accuracy Goal: 12.5 mas (1  )

52. INS NIRSpec, 12 May 2005 Image Mode Simulation 2.2 µm Centroid shift!

53. INS NIRSpec, 12 May 2005 Target Acquisition will be interesting

54. INS NIRSpec, 12 May 2005 STScI is currently working on several NIRSpec related studies MSA planning tool (J. Valenti) NIRSpec Target Acquisition Alternatives (M. Regan) What’s in phase 1 and phase 2 with JWST (J. Valenti)

55. INS NIRSpec, 12 May 2005 STScI plays a crucial role in NIRSpec MSA planning tool (J. Valenti) NIRSpec Target Acquisition Alternatives (M. Regan) What’s in phase 1 and phase 2 with JWST (J. Valenti) NIRSpec Calibration Plan ( T. Keyes) Guide Star Availability and planning (J. Valenti) Do we use Observing templates? (J. Valenti)

56. INS NIRSpec, 12 May 2005