Paul Bristow (ESO Instrumentation)

Thanks to:Andrea Modigliani, Joël Vernet & Florian Kerber, Sabine Moehler (ESO)Paolo Goldoni, Frédéric Royer & Régis Haigron (APC-SAp/CEA)

Follow the Photons – Edinburgh – October 2011

Paul Bristow (ESO Instrumentation)

Thanks to:Andrea Modigliani, Joël Vernet & Florian Kerber, Sabine Moehler (ESO)Paolo Goldoni, Frédéric Royer & Régis Haigron (APC-SAp/CEA)

Follow the Photons – Edinburgh – October 2011

Matrix Representation of Optics

Matrix Representation of Optics

ME is the matrix representation of the order m transformation performed by an Echelle grating with E at off-blaze angle . This operates on a 4D vector with components (wavelength, x, y, z).

ME is the matrix representation of the order m transformation performed by an Echelle grating with E at off-blaze angle . This operates on a 4D vector with components (wavelength, x, y, z).

ApplicationsApplications

Wavelength calibrationSimulations

Early DRS developmentEffects of modifications/upgrades

Instrument monitoring/QCAdvanced ETC?

Wavelength calibrationSimulations

Early DRS developmentEffects of modifications/upgrades

Instrument monitoring/QCAdvanced ETC?

Some backgroundSome background M. Rosa: Predictive calibration strategies: The

FOS as a case study (1995) P. Ballester, M. Rosa: Modeling echelle

spectrographs (A&AS 126, 563, 1997) P. Ballester, M. Rosa: Instrument Modelling in

Observational Astronomy (ADASS XIII, 2004) Bristow, Kerber, Rosa: four papers in HST

Calibration Workshop, 2006 UVES, SINFONI, FOS, STIS, CRIRES,

X-shooter – Bristow et al (Experimental Astronomy 31, 131, 2011)

M. Rosa: Predictive calibration strategies: The FOS as a case study (1995)

P. Ballester, M. Rosa: Modeling echelle spectrographs (A&AS 126, 563, 1997)

P. Ballester, M. Rosa: Instrument Modelling in Observational Astronomy (ADASS XIII, 2004)

Bristow, Kerber, Rosa: four papers in HST Calibration Workshop, 2006

UVES, SINFONI, FOS, STIS, CRIRES,X-shooter – Bristow et al (Experimental Astronomy 31, 131, 2011)

X-Shooter (300nm-2.5m)X-Shooter (300nm-2.5m)Commissioned 2009Vernet et al. 2011.

A & A. in pressModel for UVB, VIS

& NIR armsSame model kernelIndependent

configuration filesCross dispersed, medium res’n, single slitSingle mode (no moving components)Cassegrain & heavy => Flexure

Commissioned 2009Vernet et al. 2011.

A & A. in pressModel for UVB, VIS

& NIR armsSame model kernelIndependent

configuration filesCross dispersed, medium res’n, single slitSingle mode (no moving components)Cassegrain & heavy => Flexure

NIR Th-Ar HCL full slit

Solar like stellar point source and sky

X-shooter Flexure

X-shooter Flexure

Backbone flexureCauses movement of target on

spectrograph slitsCorrected with Automatic

Flexure Compensation exposures

Spectrograph flexureFlexing of spectrograph optical

benchCan also be measured in AFC

exposuresFirst order translation

automatically removed by pipeline

Backbone flexureCauses movement of target on

spectrograph slitsCorrected with Automatic

Flexure Compensation exposures

Spectrograph flexureFlexing of spectrograph optical

benchCan also be measured in AFC

exposuresFirst order translation

automatically removed by pipeline

VIS

UVB

NIR

Lab MeasurementsLab Measurements• NIR arm• Multi-pinhole• Translational & higher order distortions

AFC ExposuresAFC Exposures• Obtained with every science obs =>

large dataset ~300 exp from Jan – May 2011

• Single pinhole, Pen-ray lamp• Window:

• 1000x1000 win (UVB 12/VIS 14 lines)• Entire array (NIR 160 lines)

NIR UVB

VIS

Physical Model OptimisationPhysical Model Optimisation

FOR EVERY CALIBRATION EXPOSURE

Choosing “open” parametersChoosing “open” parametersAll parameters open

SlowOptimal resultDegeneracy

Physically motivated:Related to flexureConstrained by data

In these results:Prism orientation; Grating Orientation; Grating

constant; Camera focal length; Detector position and orientation

All parameters openSlowOptimal resultDegeneracy

Physically motivated:Related to flexureConstrained by data

In these results:Prism orientation; Grating Orientation; Grating

constant; Camera focal length; Detector position and orientation

NIRNIR

NIRNIR

NIRNIR

NIRNIR

(Product moment correlation)

VISVIS

VISVIS

VISVIS

UVBUVB

UVBUVB

UVBUVB

SummarySummary

Simple physical modelling approach:wavelength calibration for a number of

instrumentsRaw data simulationInstrument monitoring

Application to X-shooterFlexure monitoring

Allows identification of physical model parameters that correlate with instrument orientation

Simple physical modelling approach:wavelength calibration for a number of

instrumentsRaw data simulationInstrument monitoring

Application to X-shooterFlexure monitoring

Allows identification of physical model parameters that correlate with instrument orientation

Physical Model OptimisationPhysical Model Optimisation

QC Data9 pinhole mask, arc lamp:

Th-Ar (UVB 250 lines x 9 & VIS 390 lines x 9)pen-ray (NIR 140 lines x 9)

Daytime, Zenith (no flexure except hysteresis)1/week => small data setAutomatically processed by pipeline (ESO QC)

QC Data9 pinhole mask, arc lamp:

Th-Ar (UVB 250 lines x 9 & VIS 390 lines x 9)pen-ray (NIR 140 lines x 9)

Daytime, Zenith (no flexure except hysteresis)1/week => small data setAutomatically processed by pipeline (ESO QC)

Effe

ctiv

e ca

mer

a fo

cal l

engt

h (m

m)

Effe

ctiv

e ca

mer

a fo

cal l

engt

h (m

m)

UVB Camera temperature sensor reading (°C) VIS Camera temperature sensor reading (°C)

Det

ecto

r tip

(°)

Det

ecto

r til

t (°)

Eff

ectiv

e ca

mer

afo

cal l

engt

h (m

m)

Modified Julian Date (days)

Explain “our Physical Models” Compare to poly Uses

Calibration Simulation

Test DRS Investigate modifications/upgrades

Monitor/understand instrument behaviour History (Ballester & Rosa)

Introduce X-shooter Overview Flexure

Lab plots AFC Calibration exposures

Flexure Procedure Optimisation for 1 exposure Apply to all data Choosing open parameters

Flexure Results NIR

Residuals Sin plot Linear plots Table – highlight interesting param combinations

UVB Residuals Linear plots table

VIS Residuals Linear plots table

Flexure conclusions QC

Procedure Results

Summary

Explain “our Physical Models” Compare to poly Uses

Calibration Simulation

Test DRS Investigate modifications/upgrades

Monitor/understand instrument behaviour History (Ballester & Rosa)

Introduce X-shooter Overview Flexure

Lab plots AFC Calibration exposures

Flexure Procedure Optimisation for 1 exposure Apply to all data Choosing open parameters

Flexure Results NIR

Residuals Sin plot Linear plots Table – highlight interesting param combinations

UVB Residuals Linear plots table

VIS Residuals Linear plots table

Flexure conclusions QC

Procedure Results

Summary