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NGST support at the ST-ECF Bob Fosbury stecf/~rfosbury

NGST support at the ST-ECF Bob Fosbury http://www.stecf.org/~rfosbury. NGST@ECF. Current activities Science oversight: ISWG (NASA), SST (ESA) Performance studies Simulations PR Future plans Support of European instrument procurement process

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NGST support at the ST-ECF Bob Fosbury stecf/~rfosbury

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  1. NGST support at the ST-ECF • Bob Fosbury • http://www.stecf.org/~rfosbury

  2. NGST@ECF • Current activities • Science oversight: ISWG (NASA), SST (ESA) • Performance studies • Simulations • PR • Future plans • Support of European instrument procurement process • Provision of ESA contribution to Science Operations

  3. ESA-NASA top level schedule 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 Activity NASA Phase 1 (A/Early B) Phase 2 (Late B/C/D) Single Prime Select Instrument AO Release Instrument Selection PDR/NAR CDR Launch ESA Delta-Studies (NIR) Technology Developments MIR Studies Decision on ESA Contributions Definition Phase (NIR) Phase B (NIR) Phase C/D (NIR) MIR Instrument Development Instrument Delivery 12/01 05/01 09/03 03/04 02/02 06/09 09/04 12/06

  4. Current activities • ST-ECF contribution in 2001: • < 2 FTE including instrument science, s/w engineering and PR • Fosbury, Cristiani & Freudling members of ESA Study Science Team • Fosbury ex-officio member of ISWG

  5. Studies • Parasitic light in NGST instruments… • Cristiani, Arnouts & Fosbury, ISR 2001-01, astro-ph/0106298 • Study of slit size optimisation and crowding effects • Freudling with Arribas (STScI) • “Spoilers” in MEMS-based spectrographs • Cristiani, Pirzkal, Freudling et al. • Coherence and interference effects in multi-mirror slits: NGST spectral calibration. • Freudling et al.

  6. Future plans • ESA intends to contribute to NGST Science Operations. • NASA needs to minimise operational costs by using ‘community effort’. • ESA, through the ST-DIV, will provide instrument science, data-flow and user support components for the European instrument contributions. It will also carry out PR and educational activities. • STScI and ST-ECF are currently discussing how best to distribute this effort.

  7. Parasitic light effects • ‘Uniform’ sky (Zodi or extended continuum source) background flooding the detector with the attenuation produced by the off-MEMS • A set of ‘unwanted’ spectra (stars and galaxies) in the FOV, brighter than the target sources but attenuated by the off-MEMS — “SPOILERS” • Light scattered from the MEMS structure which does not directly enter the collimator • Imperfect filter blocking

  8. Direct and dispersed images with spoilers (bright) Toy model

  9. Range from different authors • Exploitable contrast limit set by direct leakage from PSF wings of bright sources

  10. Simulations • Catalogues based on HST observations of HDF-S • Simulations performed using selectively attenuated slitless spectroscopy methodology developed for ACS (SLIM, Pirzkal et al.). • Sensitivity and performance based on current NGST Mission Simulator

  11. Simulation parameters • R = 1000 • 12.7h exposure time in 46x1000s integrations • Target continuum sources are typical Ly-break at z ~ 3-4 with HAB ~ 24.5-25 • Emission line objects are Ly-break with added emission lines corresponding to low metallictiy HII regions scaled to give a Lya EW of 2000 Å and a typical HAB ~ 26.5-27 • FOV is 3'x3' with pixels of 0.1" = 1800x1800 pixels • The resulting spectra cover 750 pixels with 16 Å/pixel (constant) in the range 1.2 – 2.4 µm

  12. Direct image based on NICMOS HDF-S targets targets and spoilers

  13. Targets no noise Spoilers and targets no noise

  14. Targets with noise Targets and spoilers with noise

  15. Emission targets — 50% of sources have emission Emission targets & spoilers

  16. Emission targets with noise Targets and spoilers with noise

  17. R100 simulations • spectra cover 440 pixels with 100Å/pixel in the range 0.6 – 5 µm • Typical magnitudes of the candidates HAB ~ 27–28 • 1/2 of the candidates with very strong emission lines • Exposure time is 19.6hr to get a S/N~10 @ HAB ~ 28

  18. Targets and noise Spoilers and targets and noise

  19. MEMS phase errors • Study of the throughput (flux calibration) effects produced by phase differences introduced between adjacent MEMS mirrors in the NGST focal plane. • Fourier optics methodology (Freudling)

  20. OTA & mirror errors

  21. Optical layout

  22. Realisations — 1 Efficiency for randomly chosen mirror parameters The maximum tilt is 0.1°, the maximum offset 0.2µm

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