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ST-ECFAnnual Review March 14 2007 Instrument Science Activities

This annual review provides an overview of the current instrument science activities and calibration enhancements in the field. It includes spectroscopic instrument modeling, STIS and ACS slitless spectroscopy, UV spectroscopy with ACS SBC prisms, and more. The review also discusses software development and the pilot project for NICMOS HLA.

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ST-ECFAnnual Review March 14 2007 Instrument Science Activities

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  1. ST-ECFAnnual ReviewMarch 14 2007Instrument Science Activities Jeremy Walsh Wolfram Freudling Martin Kümmel Harald Kuntschner Michael Rosa

  2. Background • Current instrument science activities • Spectroscopic instrument modelling: • STIS • UV line atlas for Pt/Cr-Ne hollow cathode lamp [5000 new lines] • ESO projects – CRIRES, X-Shooter • HST slitless spectroscopy – NICMOS & ACS • HLA NICMOS Slitless Spectroscopy Pilot Project • WFC3 slitless spectroscopy ST-ECF Annual Review

  3. STIS calibration activities • Scientifically validating Instrument Model for the STIS FUV and NUV echelle modes • Assess improvements of model-based wavelength calibration v. calstis (on-going). Aim to replace calstis for these modes • Further options: • Use of model-based dispersion relations in spectral extraction (cross-dispersion profile) • Model based support for echelle flux calibration (blaze functions) • Coverage of other STIS spectral modes with benefit, such as long slit low dispersion STIS FUV MAMA lamp exposure Model v. actual lamp line positions ST-ECF Annual Review

  4. STIS Calibration Enhancement • 2D dispersion model applied to 200 E140H Echelle lamp calibration spectra. Central wavelength specified by one angle – grating tilt • Difference (obs-model) for grating tilt shows small offsets depending on the mode used, as well as a secular trend ST-ECF Annual Review

  5. ACS slitless spectroscopy • Evolution from support for NICMOS slitless grism spectroscopy (since 1997) • Activities: ground and in-orbit calibration, extraction software, user support, documentation • Impact of ACS slitless modes (only current working HST UV-optical spectrometer since Aug 2004): in Cycle 14, ACS spectroscopy held 9.7% of awarded orbits • Science spin-offs: HUDF parallels – HRC and WFC (NICMOS parallel); GRAPES (Cycle 12); PEARS (Cycle 14) • January 2007 – loss of ACS WFC and HRC. Slitless mode with two prisms still available in Solar Blind Channel (SBC) ST-ECF Annual Review

  6. Slitless spectroscopy from space [OII] z=1.38 + Low background from space + Continuous wavelength coverage – no atmospheric windows or emission lines > 1500Å + Compact PSF = High sensitivity for point and compact sources • Low spectral resolution grisms but very sensitive for continuum break spectra - Overlap of sources and contamination of spectra - Larger objects have lower spectral resolution [OIII] z=0.67 [OIII],Hαz=0.35 CIV],[CIII] z=3.19 Ly-αz=4.78 Xu et al 2007 Composite SN1a spectrum at z>1 from Reiss et al 2007 ST-ECF Annual Review

  7. UV spectroscopy with ACS SBC prisms PR110L, PR130L Following a GO alert with red-star SBC spectra, investigated possible ‘red leak’ of MAMA with spectra of blue/red standard stars. Cy16 calibration programme to better determine red sensitivity. In-orbit λcalibration using Ly-α and CIV] in two QSO’s (z=0.09, 0.17); flux calibration with standards ST-ECF Annual Review

  8. SBC Contamination Check WD-1657+343 • Our SBC prism calibration programme to check the red leak provided a check of the contamination post the January Side 2 fuse blow • Black is old data; Red is yesterday’s observation • => No obvious loss in UV sensitivity 1σ 1σ ST-ECF Annual Review

  9. software • Continue to support and develop aXe the slitless spectroscopy extraction package – available in STSDAS • Configuration and calibration files for NICMOS slitless spectra provide an alternative to the interactive NICMOSLook • Extensive use on science data – HUDF parallels, GRAPES, and PEARS programmes; SNae at z>1. IMPRS Ph.D. thesis on surveys with ACS parallel slitless spectra (B. Eder) • Spectra of dropout objects from Bouwens et al.; search for emission line sources z~6.7 z=4.76 ST-ECF Annual Review

  10. NICMOS HLA Pilot Project • Pipeline reduction of all NICMOS G141 spectra • Developed PHLAG - Pipeline for HLAGrism • End to end approach: start with the raw data, end with extracted 1D spectra in the archive • Modular, not monolithic; consists of a series of reduction steps • Uses external software: SExtractor, pyraf, MultiDrizzle, aXe, aXe2web • Implemented in Python ST-ECF Annual Review

  11. Modules of PHLAG • data retrieval from ECF archive • basic processing (calnic) and enhancements (non-linearity correction; staypuft) • background subtraction • image combination (MultiDrizzle) • object detection (SExtractor) • spectral extraction (aXe) • quality control • metadata • data ingestion into HLA archive ST-ECF Annual Review

  12. Image combination • “Best” filter • Using MultiDrizzle • Standard settings ST-ECF Annual Review

  13. Object detection • SExtractor • Conservative settings • Prime aim: get all objects for spectroscopy • “Reasonable” photometry • Boundary objects, splitting still problematic ST-ECF Annual Review

  14. Spectral extraction: aXe software ST-ECF Annual Review

  15. direct image backgr. subtr. stamp image grism image local backgr. extractedspectrum Example of a spectral extraction input intermediate steps result ST-ECF Annual Review

  16. Re-adjustment of trace • Filter wheel position is not reproducible • Require individual trace solution for every grism image • Fitting of object traces • Differences: ± 1pix over trace length ST-ECF Annual Review

  17. original readjusted Re-adjustment of wavelength zero point Shift determined with cross-correlation techniques ST-ECF Annual Review

  18. Statistics / Status • PHLAG run 1.0 on all the NICMOS G141 data in December 2006 • ~ 1000 datasets (associations) • ~ 5000 grism images • 8 day of computing time (single Linux box) • ~ 40 000 spectra • PHLAG run 2.0 in progress ST-ECF Annual Review

  19. WFC3 • UVIS channel – spare WFPC1 grism: G280 (200-500nm, @14A/pix) • IR channel – two grisms: G102 (800-1150nm; 2.2nm/pix) and G141 (1100-1700nm; 4.1 nm/pix) • Agreement signed for undertaking comprehensive WFC3 grism calibration and support activities • 2005 ground testing of UVIS and IR grisms (dispersion solutions, relative throughput). Two ISR’s • 2006 replacement of IR grisms (out of focus from substrate distortion) • 2007 testing of UVIS and IR grisms in ambient and Thermal Vacuum ST-ECF Annual Review

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