Title: Flexure analysis with the X-shooter Physical Model
1Flexure analysis with theX-shooter Physical Model
- 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
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4Matrix 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).
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10Applications
- Wavelength calibration
- Simulations
- Early DRS development
- Effects of modifications/upgrades
- Instrument monitoring/QC
- Advanced ETC?
11Some background
- M. Rosa Predictive calibration strategies The
FOS as a case study (1995) - P. Ballester, M. Rosa Modeling echelle
spectrographs (AAS 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)
12X-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 resn, single slit
- Single mode (no moving components)
- Cassegrain heavy gt Flexure
13NIR Th-Ar HCL full slit
14Solar like stellar point source and sky
15X-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
16Lab Measurements
- NIR arm
- Multi-pinhole
- Translational higher order distortions
17AFC Exposures
- Obtained with every science obs gt 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)
VIS
UVB
NIR
18Physical Model Optimisation
FOR EVERY CALIBRATION EXPOSURE
19Choosing 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
20NIR
21NIR
22NIR
23NIR
(Product moment correlation)
24VIS
25VIS
26VIS
27UVB
28UVB
29UVB
30Summary
- 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
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33Physical 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 gt small data
set Automatically processed by pipeline (ESO QC)
34Effective camera focal length (mm)
Effective camera focal length (mm)
UVB Camera temperature sensor reading (C)
VIS Camera temperature sensor reading (C)
35Detector tilt ()
Detector tip ()
Effective camerafocal length (mm)
Modified Julian Date (days)
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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