1. 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

4. Matrix Representation of Optics  M E 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).

10. Applications  Wavelength calibration  Simulations  Early DRS development  Effects of modifications/upgrades  Instrument monitoring/QC  Advanced ETC?  Wavelength calibration  Simulations  Early DRS development  Effects of modifications/upgrades  Instrument monitoring/QC  Advanced ETC?

11. Some 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)

12. X-Shooter (300nm-2.5m)  Commissioned 2009  Vernet et al. 2011. A & A. in press  Model for UVB, VIS & NIR arms  Same model kernel  Independent configuration files  Cross dispersed, medium res’n, single slit  Single mode (no moving components)  Cassegrain & heavy => Flexure  Commissioned 2009  Vernet et al. 2011. A & A. in press  Model for UVB, VIS & NIR arms  Same model kernel  Independent configuration files  Cross dispersed, medium res’n, single slit  Single mode (no moving components)  Cassegrain & heavy => Flexure

13. NIR Th-Ar HCL full slit

14. Solar like stellar point source and sky

15. X-shooter Flexure  Backbone flexure  Causes movement of target on spectrograph slits  Corrected with Automatic Flexure Compensation exposures  Spectrograph flexure  Flexing of spectrograph optical bench  Can also be measured in AFC exposures  First order translation automatically removed by pipeline  Backbone flexure  Causes movement of target on spectrograph slits  Corrected with Automatic Flexure Compensation exposures  Spectrograph flexure  Flexing of spectrograph optical bench  Can also be measured in AFC exposures  First order translation automatically removed by pipeline VIS UVB NIR

16. Lab Measurements NIR arm Multi-pinhole Translational & higher order distortions

17. AFC 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

18. Physical Model Optimisation FOR EVERY CALIBRATION EXPOSURE

19. Choosing “open” parameters  All parameters open  Slow  Optimal result  Degeneracy  Physically motivated:  Related to flexure  Constrained by data  In these results:  Prism orientation; Grating Orientation; Grating constant; Camera focal length; Detector position and orientation  All parameters open  Slow  Optimal result  Degeneracy  Physically motivated:  Related to flexure  Constrained by data  In these results:  Prism orientation; Grating Orientation; Grating constant; Camera focal length; Detector position and orientation

20. NIR

23. (Product moment correlation)

24. VIS

27. UVB

30. Summary  Simple physical modelling approach:  wavelength calibration for a number of instruments  Raw data simulation  Instrument monitoring  Application to X-shooter  Flexure monitoring  Allows identification of physical model parameters that correlate with instrument orientation  Simple physical modelling approach:  wavelength calibration for a number of instruments  Raw data simulation  Instrument monitoring  Application to X-shooter  Flexure monitoring  Allows identification of physical model parameters that correlate with instrument orientation

33. Physical Model Optimisation QC Data 9 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 set Automatically processed by pipeline (ESO QC) QC Data 9 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 set Automatically processed by pipeline (ESO QC)

34. Effective camera focal length (mm) UVB Camera temperature sensor reading (°C)VIS Camera temperature sensor reading (°C)

35. Detector tip (°) Detector tilt (°) Effective camera focal length (mm) Modified Julian Date (days)

37.  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