The Hubble Legacy Archive (HLA) Slitless Spectroscopy Project Jeremy Walsh, Martin Kümmel & Harald Kuntschner, ST-ECF STScI Slitless Spectroscopy Workshop 15-16 November 2010

The Hubble Legacy Archive (HLA) The HLA is a joint project between STScI, CADC and ST-ECF to create well-calibrated HST science data and make them accessible via user friendly interfaces Exploiting our expertise we decided to concentrate on slitless spectra, first from NICMOS then ACS Since routinely calibrated 1D and 2D spectra from these modes were not publically available, contribute a unique science product

NICMOS G141 spectra l,b distribution of pointings of NICMOS had 3 grisms (G096, G141 and G206) G141 (1.1 – 1.9μm) most used Variety of programmes from nearby cool dwarfs to high redshift QSOs Interactive extraction software developed at ST-ECF (NICMOSLook) Developed automatic PHLAG pipeline to form associations of well-aligned pointings (800), combine images, run Sextractor on combined direct images, extract 1D and 2D spectra with aXe as the engine* l,b distribution of pointings of NICMOS HLA released spectra *Config. file for G141

NICMOS HLA G141 spectra Quality checks – comparison to 2MASS photometry and direct / spectroscopic mags Human evaluation of all released spectra Rich metadata added 1923 spectra released in 2008 Freudling et al. 2008, A&A, 490, 1165

ACS G800L archive Following-on from NICMOS HLA release turned to ACS. WFC G800L most used grism – pointed (GRAPES, PEARS) and parallel programmes 153 spatial grism associations identified (out of 168 possible) but x40 increase in number of extracted spectra over NICMOS Alignment of direct images (tweakshifts) and combination (multidrizzle) Absolute astrometry by cross correlation with reference catalogues – GSC2, UCAC2, ... → <0.3’’ accuracy Distribution of 153 ACS associations in Galactic coordinates

ACS G800L processing PHLAG pipeline amended for ACS Generation of deep detection ‘white light’ image for each association SExtractor catalogues in multiple bands (F430W … F850LP, as available) Quality control of image data to ensure best alignment fluxcube method used for contamination estimation Combination of 2D drizzled spectra with aXedrizzle

HLA ACS QC of spectra For imaged stars, compared extracted spectrum with K-M templates → derived wavelength correction per association Compared direct image mags and synthesized grism mags Pre-release of 1235 spectra in HUDF parallel fields released in 2009 73581 spectra extracted in total Based on training set of 2020 randomly selected spectra, classified ‘good’ and ‘bad’ by 4 separate pairs of eyes weka automatic classification algorithm used to extend training set to whole sample Final HLA release of 47919 spectra in May 2010

HLA ACS G800L release Characterisation of released spectra in terms of emission line flux limits by comparison with ESO GOODS spectra in CDFS Concise summary page for each target Release of spectra on STScI HLA site with spatial footprints Kümmel et al. 2009 in prep. To be submitted to A&A.