ORBS and ORCS. Reduction and analysis of SITELLE's data

Transcription

1 ORBS and ORCS Reduction and analysis of SITELLE's data omas Martin (Université Laval) Laurent Drissen (Université Laval) Laurie Rousseau-Nepton (Université Laval), Alexandre Alarie (Université Laval), Simon Prunet (CFHT) 4 mai 2016

2 ORBS

3 ORBS ORBS (outils de réduction binoculaire pour SpIOMM/SITELLE) is a data reduction software for SITELLE. 2

4 ORBS Data release 1 So what is ORBS? Reduction process Combination Phase correction Flux calibration Spectral calibration Astrometry Performances

5 The first data release! DR1 version released March 30, 2016 (1 month ago) Since then all cubes from March mission have been fully reduced and calibrated. Pure push-button software: no error on any of the reduction. All SV and March cubes have been checked and released to the PI s (Wang, Spekkens, Martin, Bresolin, Lavoie, Robert, Alarie, Simard, Joncas, Shara, Herczeg). 4

6 SITELLE s Wiki /wiki-sitelle 5

7 March 2016 reduction logs /wiki-sitelle 6

8 ORBS Data release 1 So what is ORBS? Reduction process Combination Phase correction Flux calibration Spectral calibration Astrometry Performances

9 What is ORBS? Data reduction module ( lines) Core module ( lines) Data analysis tools (4 000 lines) ORB ORBS ORCS Reduction software for SITELLE and SpIOMM free-software (GNU Licence) Written in Python lines of code 5 years of development Object-Oriented layered architecture The one and only software capable of reducing SITELLE s data. 8

10 How can I know more? sourceforge.net/u/thomasorbs All the actively maintained softwares are here! 9

11 How can I know more? Browse the commits 10

12 How can I know more? Get informations on each release 11

13 How can I know even more? /orbs-doc 12

14 How can I know even more? Read the documentation: hundreds of pages of pure pleasure ;) 13

15 ORBS Data release 1 So what is ORBS? Reduction process Combination Phase correction Flux calibration Spectral calibration Astrometry Performances

16 Why a reduction software? In Raw interferometric cubes 2 sets of raw interferometric frames 1 ~ Go of raw data 2 FFT δ α Out λ Calibrated spectral cube Wavelength, ux, astrometry Because we need much more than a simple FFT to transform 2 interferometric cubes into 1 calibrated spectral cube. 15

17 Why a reduction software? 5 reduction steps: 1. Correct CCD images: bias, flat, cosmic rays (more than by cubes, 5/s) 2. Align frames (guiding errors) 3. Merge (i.e. align) cubes (2 cameras = 2 data cubes) 4. Correct for phase 5. FFT 6. Calibrate data A very sensitive guy 16

18 Why a reduction software? A not too bad raw interferogram Baseline distorsions kill Fourier! Reduced interferogram Fourier transform is very sensitive to the quality of the input signal. Any artifact on one sample creates a distorsion of the whole spectrum. 17

19 Why a reduction software? Sky Sky [NII]6563 Hα [NII]6584 Sky Sky [SII]6717 [SII]6731 Sky Raw spectrum Reduced spectrum over (2) more SNR over 2 more resolution No deformation of the continuum (low frequency noise) 18

20 The pipeline in short Combination Transformation Calibration 1 2 C y x λ δ α λ Raw interferometric cubes Combined interferometric cube Spectral cube Calibrated spectral cube Wavelength, ux, astrometry 19

21 in less short Raw interferometric cubes Standard cube + standard images Laser cube Combination C Combined interferometric cube Transformation P Phase cube δ S α λ δ L α λ y Spectral cube Calibration x λ δ α λ Calibrated spectral cube Wavelength, ux, astrometry Preprocessed calibration data is needed: standard star laser source A phase cube must also be computed 20

22 ORBS Data release 1 So what is ORBS? Reduction process Combination Phase correction Flux calibration Spectral calibration Astrometry Performances

23 2 output ports: to get all the incoming light Classical interferometer (1 output port) SITELLE's interferometer (2 output ports) Source Problem 50% of the light goes back to the source Fixed Mirror Detector 1 Source Fixed Mirror Solution Beam splitter + Compensator plate Detector Beam splitter + Compensator plate Moving mirror Moving mirror Detector 2 1 output port = half the light! 22

24 2 output ports: to correct for transmission variations 21:05 Day 1 23:25 21:45 Day 2 23:00 Transmission Step index Transmission uncertainty < 5e-4 (0.05%) Sky transmission variations modulates the interferograms Sum of light on both ports = relative transmission. 23

25 2 output ports: to remove non-modulated scattered light Before First night Camera 1 interferogram Second night Background rising (up to 15 times its normal value) Combined interferogram Normal background intensity A er Background peak has disappeared! Non-modulated scattered light must be removed! Combination automatically removes it. 24

26 ORBS Data release 1 So what is ORBS? Reduction process Combination Phase correction Flux calibration Spectral calibration Astrometry Performances

27 What is the phase? The output of a Fourier transform is a complex vector A complex number can be represented by amplitude/phase instead of real/imaginary Im Amplitude Phase Re 26

28 Effects of phase correction on the spectrum Without phase correction real spectrum and imaginary spectrum are mixed No phase correction = spectrum = Re 2 + Im 2 With phase correction: spectrum = Re Power spectrum Real part Imaginary part Wavelength (nm) 27

29 Effects of phase correction on the spectrum Phase corrected spectrum (sinc) Gaussian noise distribution -σ 0 +σ Power spectrum (sinc 2 ) Wavelength (nm) Squared Gaussian noise distribution -σ 0 +σ Using power spectrum is bad Noise is 2 higher Noise is folded (N 2 ) Resolution is degraded 28

30 ORBS Data release 1 So what is ORBS? Reduction process Combination Phase correction Flux calibration Spectral calibration Astrometry Performances

31 Absolute flux error Integrated spectrum Hα Measured ux Standard ux Hα (±2.83) % [NII] λ (±3.02) % 0.91 Flux in erg/cm 2 /s [NII] λ6563 [NII] λ6584 HeI λ6678 Fit Data [SII] 6717, [NII]λ6584/Hα ratio Wavelength in nm BONUS! Comparison with M1-71 spectrophotometry (Wright et al. 2005) (the 3% error comes from Wright s data) 30

32 Absolute flux error Integrated ux [10-14 erg/s/cm2/a] SN1 SN2 SN3 CALIFA's integrated spectrum CALIFA's imagery calibration SITELLE's integrated spectrum Wavelength [A] Note: SITELLE's spectra have been convoluted to respect PPAK's resolution Note: A correction factor of 0.65 has been applied to consider PPAK's lling factor Comparison with NGC628 integrated spectrum (CALIFA survey, Sanchez et al. 2010) 31

33 Absolute flux error Object NGC3344 Hα vs. SpIOMM -4% ±2% (Rousseau-Nepton et al.) Hα + [NII]λ6584 vs. SpIOMM -4% ±3% M1-71 Hα vs Wright (2005) -7% ±3% [NII]λ6584 vs Wright (2005) -11% ±3% NGC628 SN1 vs. CALIFA -6% ±6% SN2 vs. CALIFA -7% ±6% SN3 vs. CALIFA -9% ±6% HETDEX field Lyα flux of 20 high redshift -5%±7% (Drissen et al.) galaxies General bias of -5% (bad estimation of the modulation efficiency). Once corrected an uncertainty of ± 5% is a conservative estimation. 32

34 Relative flux error Phase correction flux error is 1% Relative flux error dominated by flat field error 1% on 80% of the field 33

35 ORBS Data release 1 So what is ORBS? Reduction process Combination Phase correction Flux calibration Spectral calibration Astrometry Performances

36 Good news With a Fourier transformed spectrum Spectral calibration depends only on the zero point. Relative wavelength error of the lines in a single spectrum is impossible. Wavelength (nm) Zero point is the only uncertainty 35

37 Absolute velocity error Absolute wavelength calibration is based on a HeNe nm But Nominal wavelength is not well known + drift with time Measured absolute error is around 70 km/s since the beginning of the year ( = HeNe nm). Can be corrected via sky lines with a precision < 0.5 km/s Wavelength (nm) 36

38 Relative velocity error Relative error is the pixel-to-pixel variation of the zero point UGC7899 (Spekkens et al.) IC348 (Herczeg et al.) PG (Wang et al.) km/s Sky lines velocity difference (in km/s) < 5 km/s of relative velocity error on 90% of the FOV In most of the cubes a sky lines map can be created with ORCS to reduce the relative error to < 1 km/s 37

39 ORBS Data release 1 So what is ORBS? Reduction process Combination Phase correction Flux calibration Spectral calibration Astrometry Performances

40 WCS WCS comparison with USNO-B1 catalog WCS error < 1.5 (5 pixels) in 90% of the field 39

41 ORBS Data release 1 So what is ORBS? Reduction process Combination Phase correction Flux calibration Spectral calibration Astrometry Performances

42 ORBS Performances Fully Automated, robust and easy to use All cubes are reduced without any human intervention Launched via a very simple command line Fast Parallelized at 90% Process a 1000 steps cube in less than 7 hours Most cubes are processed in less than 3 hours (<500 steps). 41

43 ORBS Performances Scalable Process 68 Go of raw data with less than 23 Go of RAM (max performances) Needed RAM can go under 8 Go with reduced performances Can be scaled to be used on any regular computer Free, well-coded and maintainable Respect free software guidelines Written in Python Object-Oriented Fully commented and documented 42

44 ORCS + Viewers

45 ORCS + Viewers ORCS Viewers

46 ORCS ORCS (outils de réduction de cubes spectraux) is a fit engine for fast analysis of spectral cubes. 44

47 What is ORCS? ORCS: a fit engine A wide variety of models: emission/absorption spectrum continuum filter (to fit lines on the border of the filter) possibility of adding model grids (e.g. stellar population) Multiple constraints: co-varying velocity / FWHM / amplitude = enhance the precision of the fit by using all the information. 45

48 Typical output Each fitted parameter can be mapped. 1 emission line = 6 maps Amplitude FWHM Velocity Amplitude t error FWHM t error Velocity t error 46

49 Hα emission line from ORCS on IC443 (Alarie et al.) e e e e e e-17 6:18: Right ascension : Flux (in erg/cm2/s/a) 5.35e e-17 Declination 2.88e-16 44: : : : : : :50: : : : :00.0 Declination 44: : : : : : :50: : : : : e e :18: Right ascension : Velocity (in km/s) 47

50 Other features sky lines fit automatic correction of heliocentric velocity sky removal 48

51 Sky lines + HII region lines fit [NII] λ6563 Hα [NII] λ6584 Flux (in ergs/cm 2 /s) [SII] λ6717 [SII] λ6731 Data Fit Residual Wavelength (in nm) Absolute velocity calibration with a precision of 500 m/s! 49

52 Sky lines + 2 HII regions lines 2 HII components at : [±1.3] km/s and 3.33 [±3.33] km/s Flux (in ergs/cm 2 /s) [NII] λ6563 Hα [NII] λ6584 [SII] λ6717 [SII] λ6731 Wavelength (in nm) Wavelength (in nm) A bubble in IC348? 50

53 ORCS + Viewers ORCS Viewers

54 2D viewer Visualize your data cube Extract a spectrum and t it! Fit parameters Fit results 52

55 3D viewer videos/3dviewer.avi 53

56 Conclusion

57 To conclude First data release All data has been fully reduced with ORBS without any human intervention. ORBS has proved to be functional, fast, precise and robust. We have discovered small but obvious calibration biases (easy to correct) Next data release in a few months: flux error < 2-3% absolute+relative wavelength error < 1 km/s ORCS is a precision tool especially developped for SITELLE s data ORCS and viewers now under strong development but ready to be used by the community. Releasing tools and working with data will be the best way to improve them. 54