ST-ECFAnnual Review March 14 2007 Instrument Science Activities Jeremy Walsh Wolfram Freudling Martin Kümmel Harald Kuntschner Michael Rosa

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 14 March 2007 ST-ECF Annual Review

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 14 March 2007 ST-ECF Annual Review

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 14 March 2007 ST-ECF Annual Review

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) 14 March 2007 ST-ECF Annual Review

Slitless spectroscopy from space + 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 [OII] z=1.38 [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 14 March 2007 ST-ECF Annual Review

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 14 March 2007 ST-ECF Annual Review

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 14 March 2007 ST-ECF Annual Review

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 14 March 2007 ST-ECF Annual Review

NICMOS HLA Pilot Project Pipeline reduction of all NICMOS G141 spectra Developed PHLAG - Pipeline for HLA Grism 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 14 March 2007 ST-ECF Annual Review

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 14 March 2007 ST-ECF Annual Review

Image combination “Best” filter Using MultiDrizzle Standard settings 14 March 2007 ST-ECF Annual Review

Object detection SExtractor Conservative settings Prime aim: get all objects for spectroscopy “Reasonable” photometry Boundary objects, splitting still problematic 14 March 2007 ST-ECF Annual Review

Spectral extraction: aXe software 14 March 2007 ST-ECF Annual Review

Example of a spectral extraction input intermediate steps result grism image local backgr. backgr. subtr. stamp image extracted spectrum direct image 14 March 2007 ST-ECF Annual Review

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 14 March 2007 ST-ECF Annual Review

Re-adjustment of wavelength zero point readjusted original Shift determined with cross-correlation techniques 14 March 2007 ST-ECF Annual Review

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 14 March 2007 ST-ECF Annual Review

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 14 March 2007 ST-ECF Annual Review