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The aXe software

The aXe software. Martin Kümmel, J. Walsh, H. Kuntschner. S pace T elescope- E uropean C oordinating F acility November 15 th , 2010. Outline. Overview Introduction to aXe Reducing data with aXe (input/output)

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The aXe software

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  1. The aXe software Martin Kümmel, J. Walsh, H. Kuntschner Space Telescope-European Coordinating Facility November 15th, 2010

  2. Outline • Overview • Introduction to aXe • Reducing data with aXe (input/output) • Specific topics in aXe (contamination, extraction direction, co-adding data) • Simulations with aXeSIM • aXe2web: visualize results from aXe • Discussion Slitless Spectroscopy Workshop

  3. Software tools • aXe: • spectral extraction • current version 2.1 • spectral extraction • integrated in PyRAF/IRAF • part of STSDAS 3.12 • aXeSIM: • slitless simulation • current version: 1.4 • simulation of slitless data • integrated in PyRAF/IRAF package • Part of STSDAS 3.12 • aXe2web: • visualization • current version: 2.1 • visualisation and quality control • python program Slitless Spectroscopy Workshop

  4. aXe tasks in PyRAF • axeprep • background subtraction (global) • image normalization (exp-time) • axecore • beam definition • beam collection • flat-fielding • contamination estimate • 1D-extraction (individual) Slitless Spectroscopy Workshop

  5. aXe tasks in PyRAF (cont.) • drzprep • prepare axedrizzle • pixel space  image space • compute coefficients • axedrizzle • produce 2D grism stamps (with error, exp-time map…) • cosmic ray rejection • extract 1D spectra Slitless Spectroscopy Workshop

  6. aXe tasks in PyRAF (cont.) • iolprep • prepare Input Object Lists • project coordinates • fcubeprep • prepare”fluxcube files” • for contamination estimate Slitless Spectroscopy Workshop

  7. input data yes no axeprep axecore back=no axecore back=yes no yes yes no drzprep drzprep spectra spectra axedrizzle axedrizzle spectra spectra Data reduction strategies global background axedrizzle ACS/prism WFC3/IR ACS/G800L Slitless Spectroscopy Workshop

  8. Working with aXe • PyRAF/IRAF GUI • Command line: axecore WFC3.conf back=“NO” extrfwhm=3.0… • python scripts (“python run_axe.py”) Slitless Spectroscopy Workshop

  9. Reducing data with aXe (input) • object positions (reference point) from direct imaging • definition of the wavelength zeropoint Slitless Spectroscopy Workshop

  10. Reducing data with aXe (input) • Input Object List: • for zeropoint of wavelengthscale • contains information on individual objects • SExtractor catalog format • SExtractor list numer  aXe object identification # 1 NUMBER Running object number # 1 NUMBER Running object number # 2 X_IMAGE Object position along x [pixel] # 3 Y_IMAGE Object position along y [pixel] # 4 A_IMAGE Profile RMS along major axis [pixel] # 5 B_IMAGE Profile RMS along minor axis [pixel] # 6 THETA_IMAGE Position angle (CCW/x) [deg] # 7 X_WORLD Barycenter position along world x axis [deg] # 8 Y_WORLD Barycenter position along world y axis [deg] # 9 A_WORLD Profile RMS along major axis (world units) [deg] # 10 B_WORLD Profile RMS along minor axis (world units) [deg] # 11 THETA_WORLD Position angle (CCW/world-x) [deg] # 12 MAG_F905W Kron-like elliptical aperture magnitude [mag] 1 354.3 1788.0 1.38 0.93 -61.9 5.32227466e+01 -2.78269501e+01 1.15391e-05 7.81022e-06 -77.1 27.33 2 430.8 1881.1 4.85 3.41 134.0 5.32222385e+01 -2.78263217e+01 4.04609e-05 2.84565e-05 84.8 22.77 3 445.9 1745.3 1.50 1.32 -140.9 5.32223037e+01 -2.78259023e+01 1.25505e-05 1.10465e-05 6.7 26.60 4 508.4 1417.7 1.09 0.73 -85.6 5.32249088e+01 -2.78258256e+01 9.13685e-06 6.09757e-06 -49.2 27.80 5 550.3 1007.1 2.07 1.08 -81.1 5.32247112e+01 -2.78252172e+01 1.72606e-05 9.00725e-06 -54.4 26.86 Slitless Spectroscopy Workshop

  11. Reducing data with aXe (input) • Input Image List • organization of direct images the objects thereon and the associated grism images Configuration and calibration files • aXe configuration file: contains the instrument specific information for the various beams • aXe calibration files: • flatfield • sensitivity curves ib6o21qmq_flt.fits ib6o21qnq_flt_1.cat ib6o21qnq_flt.fits ib6o21qoq_flt.fits ib6o21qqq_flt_1.cat ib6o21qqq_flt.fits ib6o21r6q_flt.fits ib6o21r7q_flt_1.cat ib6o21r7q_flt.fits ib6o21r8q_flt.fits ib6o21raq_flt_1.cat ib6o21raq_flt.fits INSTRUMENT WFC3 CAMERA IR SCIENCE_EXT SCI ; Science extension FFNAME WFC3.G141.flat.cube.fits DQMASK 16383 # First order (BEAM A) BEAMA 15 190 MMAG_EXTRACT_A 35 # Trace description DYDX_ORDER_A 1 DYDX_A_0 1.977023666 0.000047900 -0.001888998 # X and Y Offsets XOFF_A 0.0 YOFF_A 0.0 # Dispersion solution DISP_ORDER_A 1 DLDP_A_0 8912.38417 0.104823806 0.009107301 SENSITIVITY_A wfc3_abscal_IRg141_1st_sens.fits Slitless Spectroscopy Workshop

  12. Reducing data with aXe (output) • extracted spectra: • in e/s (with error) • in flux (with error) • contamination estimate • 2D grism stamp images • lots of intermediate results and auxiliary files Extracted spectrum 2D stamp image Slitless Spectroscopy Workshop

  13. Contamination • no slit • low dispersion • happens everywhere • the aXe solution: • shape information • flux information • slitless spectral model • quantitative estimate of contamination Slitless Spectroscopy Workshop

  14. Contamination (cont.) Slitless Spectroscopy Workshop

  15. Extraction geometries • many possibilities for extraction width and direction • depending on the science case: • fixed width, perpendicular to trace (for point-like objects) • flexible width, perpendicular to trace (WFC3/IR survey) • flexible width, variable direction (total user control, might be dangerous) • Flexible width SNR optimized direction (ACS/WFC) • minimum size set in configuration file (POBSIZE) Slitless Spectroscopy Workshop

  16. aXedrizzle • co-adding dithered data • only a single re-sampling • weighting of different exposure times correctly handled • problem detection on the 2D stamp • 2D stamps fully calibrated! Slitless Spectroscopy Workshop

  17. aXedrizzle with pixel rejection • new in aXe version 2.1 (part of STSDAS 3.12) • detection of deviant pixels (comparable to MultiDrizzle in direct imaging) • cleaner spectra! Slitless Spectroscopy Workshop

  18. aXedrizzle with pixel rejection (cont.) ~50% of the spectra in the ERS G141 data set contain a bin with sig>2.0!!! Slitless Spectroscopy Workshop

  19. task axesim • preparation: • make fake images • prepare spectral templates • Simulation: • compute grism image • compute direct image • add noise • compose result image “normal” aXe extraction aXeSIM • symmetric to aXe extraction • input very similar to aXe • uses the aXe configuration and calibration files • accepts minimal and more sophisticated input • software basis of aXe and aXeSIM has merged • two packages are interdependent Slitless Spectroscopy Workshop

  20. # 1 NUMBER # 2 X_IMAGE # 3 Y_IMAGE # 4 A_IMAGE # 5 B_IMAGE # 6 THETA_IMAGE # 7 MAG_F1155W # 8 SPECTEMP # 9 Z # 10 MODIMAGE 1 450.0 170.0 1.6 1.3 270.0 21.0 0 0.0 0 2 460.0 110.0 1.5 1.2 45.0 21.0 0 0.0 0 3 450.0 130.0 1.9 1.5 -70.0 21.0 5 2.0 3 4 450.0 80.0 1.5 1.5 90.0 21.0 0 0.0 0 5 500.0 95.0 1.5 1.5 90.0 20.0 3 0.5 1 6 500.0 120.0 1.5 1.5 90.0 20.0 0 0.7 1 7 650.0 105.0 2.5 1.5 0.0 21.5 0 0.0 0 8 350.0 150.0 1.5 1.0 90.0 21.5 0 0.0 0 9 550.0 220.0 1.5 1.5 10.0 21.5 0 0.0 0 10 50.0 105.0 1.5 1.5 135.0 21.5 0 0.0 0 11 510.0 140.0 1.5 1.5 90.0 20.0 2 0.9 1 12 490.0 160.0 1.5 1.5 90.0 20.0 5 2.1 1 13 570.0 177.0 1.5 1.5 90.0 20.0 4 1.3 0 14 400.0 212.0 1.5 1.5 90.0 20.0 1 1.5 1 similar, but distinct from Input Object List xy-position Gaussian shape or reference to model source brightness or reference to template spectrum UDF Simulations Model Object Table Slitless Spectroscopy Workshop

  21. aXeSIMweb • aXeSIM as a web application • easy to use • ideal for Phase I preparation • introduction for aXeSIM http://www.stecf.org/instruments/aXeSIMweb/ Slitless Spectroscopy Workshop

  22. aXe2web • browsable web pages for extracted spectra • uses aXe catalogs and images and spectra • index and overview available • flexible and configurable Slitless Spectroscopy Workshop

  23. Strong aspects of aXe • scriptable (python) • flexible • many intermediate products • delivers spectra + errors • well documented (manual, ISR’s, refereed paper, conference proceedings, Newsletter) • widely used (has seen lots of data) • It works! Slitless Spectroscopy Workshop

  24. Possible future developments • better software distribution (third party libraries) • pure python package • better support of WFC3/G280 • iterative extraction • better object summaries • less tasks ( multiaxe) • automatic pipeline (like ACS/G800L in HLA) Slitless Spectroscopy Workshop

  25. Software structure libraries CFITSIO GSL Slitless Spectroscopy Workshop

  26. hmmm… No!!!! extraction direction? aXe and G280 Slitless Spectroscopy Workshop

  27. Object summary and pipeline • object summary covering: • object position • object shape • extraction width • wavelength range • SNR’s • extension of the ACS/G800L HLA pipeline to WFC3 G102 and G141 ACS/G800L preview from HLA pipeline Slitless Spectroscopy Workshop

  28. Example results Two HST orbits: emission lines down to magAB(F140W)=24.5 Slitless Spectroscopy Workshop

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