ORBS and ORCS

�omas Martin (Université Laval)Laurent Drissen (Université Laval)

Laurie Rousseau-Nepton (Université Laval), Alexandre Alarie (Université Laval), Simon Prunet (CFHT)

4 mai 2016

Reduction and analysis of SITELLE's data

ORBS

ORBS

ORBS (outils de réduction binoculaire pour SpIOMM/SITELLE) is

a data reduction software for SITELLE.

2

ORBS

Data release 1

So what is ORBS ?

Reduction process

Combination

Phase correction

Flux calibration

Spectral calibration

Astrometry

Performances

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 thereduction.

• All SV and March cubes have been checked and releasedto the PI’s (Wang, Spekkens, Martin, Bresolin, Lavoie,

Robert, Alarie, Simard, Joncas, Shara, Herczeg).

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SITELLE’s Wiki

132.203.11.199/wiki-sitelle

5

132.203.11.199/wiki-sitelle

March 2016 reduction logs

132.203.11.199/wiki-sitelle

6

132.203.11.199/wiki-sitelle

ORBS

Data release 1

So what is ORBS ?

Reduction process

Combination

Phase correction

Flux calibration

Spectral calibration

Astrometry

Performances

What is ORBS ?

ORBCore module (23 000 lines)

ORCSData analysis tools(4 000 lines)

ORBS(13 000 lines)Data reduction module

• Reduction software forSITELLE and SpIOMM

• free-software (GNULicence)

• Written in Python• 40 000 lines of code• 5 years of development• Object-Oriented layered

architecture

• The one and only software capable of reducing SITELLE’sdata.

8

How can I know more ?

sourceforge.net/u/thomasorbs All the actively maintained

softwares are here !

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sourceforge.net/u/thomasorbs

How can I know more ?

Browse the commits

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How can I know more ?

Get informations on each release

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How can I know even more ?

132.203.11.199/orbs-doc

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132.203.11.199/orbs-doc

How can I know even more ?

Read the documentation: hundreds of pages of pure pleasure ;)

13

ORBS

Data release 1

So what is ORBS ?

Reduction process

Combination

Phase correction

Flux calibration

Spectral calibration

Astrometry

Performances

Why a reduction software ?

1 2

α

δ

λ

Calibrated spectral cubeWavelength, �ux, astrometry

Raw interferometric cubes2 sets of 400 - 1000 raw interferometric frames

~ 32 - 64 Go of raw data

FFT

In

Out

Because we need much more than a simple FFT to transform 2

interferometric cubes into 1 calibrated spectral cube.15

Why a reduction software ?

5 reduction steps:

1. Correct CCD images: bias, flat,

cosmic rays (more than 20 000 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

Why a reduction software ?

A not too bad raw interferogram

Reduced interferogram

Baseline distorsions kill Fourier !

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

Why a reduction software ?

Hα

[NII

]658

4

[NII

]656

3

Sky

Sky

Sky

Sky

Sky

Raw spectrum

Reduced spectrum

[SII

]671

7[S

II]6

731

• over√

(2) × more SNR• over 2 × more resolution• No deformation of the continuum (low frequency noise) 18

The pipeline in short

Combination

Transformation

Calibration

1 2

x

y

λ

α

δ

λ

C

Raw interferometric cubes

Calibrated spectral cubeWavelength, �ux, astrometry

Spectral cube

Combined interferometric cube

19

in less short. . .

Combination

Transformation

Calibration

1 2

C

Raw interferometric cubes

x

y

λ

α

δ

λ

Calibrated spectral cubeWavelength, �ux, astrometry

Spectral cube

Combined interferometric cube

P

1 2

α

δ

λS

1 2

α

δ

λL

Standard cube+ standard images Laser cube

Phase cube

• Preprocessed calibration data is needed:• standard star• laser source

• A phase cube must also be computed

20

ORBS

Data release 1

So what is ORBS ?

Reduction process

Combination

Phase correction

Flux calibration

Spectral calibration

Astrometry

Performances

2 output ports: to get all the incoming light

Beam splitter+ Compensator plate

Fixed Mirror

Moving mirror

Detector

Source Problem50% of the light goes

back to the source

Classical interferometer(1 output port)

SITELLE's interferometer(2 output ports)

Solution

Detector 1

Detector 2

Source

Moving mirror

Beam splitter+ Compensator plate

Fixed Mirror

• 1 output port = half the light !

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2 output ports: to correct for transmission variations

Step index

Tran

smiss

ion

21:05 23:25 21:45 23:00Day 1 Day 2

Transmission uncertainty < 5e-4 (0.05%)

• Sky transmission variations modulates the interferograms• Sum of light on both ports = relative transmission.

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2 output ports: to remove non-modulated scattered light

Combined interferogram

Background rising (up to 15 times its normal value)

Normal background intensity

First night Second night

Camera 1 interferogram

Before

A�er Background peak has disappeared !

• Non-modulated scattered light must be removed !• Combination automatically removes it.

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ORBS

Data release 1

So what is ORBS ?

Reduction process

Combination

Phase correction

Flux calibration

Spectral calibration

Astrometry

Performances

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

Amplitud

e

Phase

Re

Im

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Effects of phase correction on the spectrum

Without phase correction real spectrum and imaginary spectrum

are mixed

• No phase correction =⇒ spectrum =√

Re2 + Im2

• With phase correction: spectrum = Re

Wavelength (nm)

Power spectrumReal partImaginary part

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Effects of phase correction on the spectrum

Wavelength (nm)

+σ-σ 0

Phase corrected spectrum (sinc)

Gaussian noise distribution

+σ-σ 0

Power spectrum (sinc2)

Squared Gaussian noise distribution

Using power spectrum is bad

• Noise is√

2 higher

• Noise is folded (N 2)• Resolution is degraded

28

ORBS

Data release 1

So what is ORBS ?

Reduction process

Combination

Phase correction

Flux calibration

Spectral calibration

Astrometry

Performances

Absolute flux error

[NII] λ6584Hα -6.88 (±2.83) %

-10.87 (±3.02) %Measured �uxStandard �ux

Flux

in e

rg/c

m2 /

s

Wavelength in nm

Hα

HeI

λ66

78

[SII

] �67

17,3

1

[NII

] λ65

84

[NII

] λ65

63

FitData

Integrated spectrum

0.17

0.32

0.47

0.61

0.76

0.91

[NII]λ6584/Hα ratioBONUS !

Comparison with M1-71 spectrophotometry (Wright et al. 2005)

(the 3% error comes from Wright’s data)30

Absolute flux error

SN1 SN2 SN3

4000 4500 5000 5500 6000 6500 7000

20

40

60

80

100In

tegr

ated

�ux

[10-

14 e

rg/s

/cm

2/A

]

Wavelength [A]

CALIFA's integrated spectrumCALIFA's imagery calibrationSITELLE's integrated spectrum

Note: SITELLE's spectra have been convoluted to respect PPAK's resolutionNote: 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

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 modulationefficiency).

• Once corrected an uncertainty of ± 5% is a conservativeestimation.

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Relative flux error

• Phase correction flux error is � 1%• Relative flux error dominated by flat field error ∼ 1% on

80% of the field

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ORBS

Data release 1

So what is ORBS ?

Reduction process

Combination

Phase correction

Flux calibration

Spectral calibration

Astrometry

Performances

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.

Zero point is the only uncertaintyWavelength (nm)

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Absolute velocity error

• Absolute wavelength calibration is based on a HeNe laser@543.5 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 ' 543.62 nm).• Can be corrected via sky lines with a precision < 0.5 km/s

Wavelength (nm)

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Relative velocity error

Relative error is the pixel-to-pixel variation of the zero point

IC348 (Herczeg et al.)UGC7899 (Spekkens et al.) PG1216+069 (Wang et al.)

Sky lines velocity difference (in km/s)

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

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ORBS

Data release 1

So what is ORBS ?

Reduction process

Combination

Phase correction

Flux calibration

Spectral calibration

Astrometry

Performances

WCS

WCS comparison with USNO-B1 catalog

• WCS error < 1.5” (5 pixels) in 90% of the field

39

ORBS

Data release 1

So what is ORBS ?

Reduction process

Combination

Phase correction

Flux calibration

Spectral calibration

Astrometry

Performances

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 (

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

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ORCS + Viewers

ORCS + Viewers

ORCS

Viewers

ORCS

ORCS (outils de réduction de cubes spectraux) is a fit engine for

fast analysis of spectral cubes.

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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 allthe information.

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Typical output

• Each fitted parameter can be mapped.

Velocity�t error

FWHM�t error

Amplitude�t error

Amplitude FWHM Velocity

1 emission line = 6 maps

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Hα emission line from ORCS on IC443 (Alarie et al.)

6:18:00.0 55.0 50.0 45.0 40.0 35.0 30.0 25.0 17:20.0 15.0

54:0

0.0

53:0

0.0

52:0

0.0

51:0

0.0

22:5

0:00

.049

:00.

048

:00.

047

:00.

046

:00.

045

:00.

044

:00.

0

Right ascensionD

eclin

atio

n24

40

55

71

86

101

117

132

148

163

179

6:18:00.0 55.0 50.0 45.0 40.0 35.0 30.0 25.0 17:20.0 15.0

54:0

0.0

53:0

0.0

52:0

0.0

51:0

0.0

22:5

0:00

.049

:00.

048

:00.

047

:00.

046

:00.

045

:00.

044

:00.

0

Right ascension

Dec

linat

ion

1.45e-17

5.35e-17

9.26e-17

1.32e-16

1.71e-16

2.10e-16

2.49e-16

2.88e-16

3.28e-16

3.67e-16

4.06e-16

Velocity (in km/s)Flux (in erg/cm2/s/A)

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Other features

• sky lines fit• automatic correction of heliocentric velocity• sky removal

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Sky lines + HII region lines fit

Flux

(in

ergs

/cm

2 /s)

[NII

] λ65

84

Hα

[NII

] λ65

63

[SII

] λ67

31[S

II] λ

6717

DataFitResidual

Wavelength (in nm)

Absolute velocity calibration with a precision of 500 m/s !49

Sky lines + 2 HII regions lines

2 HII components at : 49.35 [±1.3] km/s and 3.33 [±3.33] km/s

Wavelength (in nm) Wavelength (in nm)

Flux

(in

ergs

/cm

2 /s)

[NII

] λ65

84

Hα

[NII

] λ65

63

[SII

] λ67

31

[SII

] λ67

17

A bubble in IC348 ?

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ORCS + Viewers

ORCS

Viewers

2D viewer

Visualize your data cube Extract a spectrum and �t it !

Fit resultsFit parameters

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3D viewer

videos/3dviewer.avi

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videos/3dviewer.avi

Conclusion

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 forSITELLE’s data

• ORCS and viewers now under strong development butready to be used by the community.

• Releasing tools and working with data will be the best way toimprove them. 54

ORBSData release 1So what is ORBS ?Reduction processCombinationPhase correctionFlux calibrationSpectral calibrationAstrometryPerformances

ORCS + ViewersORCSViewers

Conclusion